Having just reviewed the 2015 book On the Wing, I continue my brief two-part foray into the evolution of flight with Taking Flight by writer and conductor Lev Parikian. In a book that is full of wonder and humour, he marvels at the many different strategies for flying that have evolved in primarily insects and birds. However, the somewhat muddled explanations of flight mechanics and limited attention for other groups make for a somewhat uneven book.

Taking Flight: The Evolutionary Story of Life on the Wing, written by Lev Parikian, published by Elliott & Thompson in May 2023 (hardback, 282 pages)

Parikian is the author of five previous books on music and the natural world. His 2018 Why Do Birds Suddenly Disappear? told how, as a self-proclaimed lapsed birdwatcher, he refound his passion for it in his fifties. He has also contributed to the BTO anthology Red Sixty Seven, The Guardian‘s Country Diary column, and Bird Watching magazine, so knows a thing or two about birds. Now, in his sixth book, he delves into the story of the evolution of animal flight.

Flying creatures are so ubiquitous in our lives that it is easy to take the whole phenomenon for granted. The strongest impression this book leaves is that of Parikian seeking to re-enchant his readership, grabbing you by the scruff of the neck from the opening encounter with a blue tit to remind you that: “It flies. It. Flies.” (p. xiii). This sense of wonder infuses the book, whether it is flies capable of landing upside down on the ceiling—”we should, if we were properly curious and fascinated, be texting, ‘I BEHELD A MIRACLE’ to all our friends” (p. 59)—or awaiting the annual return of swifts to our skies—”as I roam the streets of south London, I’m a liability […] head up, staggering shambolically into bollards and bus shelters, ready to harangue random passers-by with a hoarse, deranged bark of ‘They’re here!’” (p. 199).

I will not deny that his enthusiasm is infectious and is helped along by a healthy dollop of humour and jokes. There are colourful descriptions of male stag beetles with massive mandibles whose ungainly flight says “We’re not really supposed to be doing this, but if you absolutely insist” (p. 50), or of pterosaurs whose fourth finger is “noticeably, weirdly, excessively long. A veritable überfinger. The kind of thing you’d use to get a ping-pong ball out from behind a radiator” (p. 111). There are pop-culture references, such as swifts whose “chief asset is speed. Speed and manoeuvrability. Speed, manoeuvrability and a fanatical devotion to the air” (p. 201). There is the occasional well-timed f-bomb, such as aforementioned flies landing upside down: “it seems weird and unnatural, a defiant ‘fuck you’ to everything we think we know about gravity” (p. 59). And I have yet to come across a more amusing explanation of the difference between taxonomical lumpers and splitters: “a ‘lumper’ would regard all Magnum ice-creams as the species ‘Magnum’, regardless of flavour; a splitter would deem the Double Raspberry Magnum and the Salted Caramel & Glazed Almond Magnum two separate species. Glad to have cleared that up for you” (p. 153). Admittedly, some of the jokes are a bit of a stretch. How did pterosaurs get airborne? “Perhaps they flung each other into the air with a primitive trebuchet” (p. 113). I guffawed my way through this book, but your mileage might vary, depending on how you like your popular science.

“The strongest impression this book leaves is that of Parikian seeking to re-enchant his readership, grabbing you by the scruff of the neck from the opening encounter with a blue tit to remind you that: It flies. It. Flies.“

Entertaining as Taking Flight is, I do have some criticism. First, the book feels somewhat uneven due to his choice to spend six chapters each on insects and birds (because they have the greatest diversity in morphology and flight styles), but only one each on pterosaurs and bats. As a consequence, many chapters are not strictly about the evolution of flight, but more about the diversity of flyers that evolution has given rise to. Chapters feature, for example, bee swarming and butterfly migration, or the adaptations that allow hummingbirds to hover and albatrosses to soar. He includes most of the theories on the evolution of flight covered in On the Wing and has read up on the literature, mentioning, for instance, the quadrupedal launching model for pterosaurs that Alexander left out. However, he omits other ideas, for instance, how flight in insects might have started simply by steering one’s fall (so-called directed aerial descent), as was reported for ants by Steven Yanoviak and colleagues.

Second are Parikian’s explanations of the biomechanics of flight. Rather than dedicating a chapter to the basics, he delves straight into the story of evolution, starting with the earliest insects, and drip-feeds you bits of information throughout the book. The opening Author’s Note admits he has come to this topic as an eager layman, but despite having consulted relevant literature, his explanations leave something to be desired. For example, he writes that lift is generated by leading-edge vortices increasing the speed of air flowing over the wing, which lowers air pressure, which increases lift. However, both Alexander and Gregory Paul point out that this is an incomplete and even misleading explanation. If I have understood these authors correctly, most, if not all, lift is generated by the downward orientation of the trailing edge (the back of the wing), which sends the airflow down and back. It is the downward component of this, and the vortices formed behind the trailing edge, that generate lift. Furthermore, even as Parikian defines certain terms, he uses others without explaining what they are, such as angle of attack and camber. Plus, he makes it sound as if camber is the same as a wing’s surface area, which it is not; it refers to the curvature of the wing, more specifically, the difference in curvature between the upper and undersides. Thus, when he explains that bees deal with the additional load of pollen by making their wing strokes deeper, I am not actually sure what that looks like. There are no diagrams included, which would have been helpful given the level at which this book is pitched. Unfortunately, I am left with the impression that, unless you are already familiar with the basics of animal flight, you might come away with a muddled understanding of it.

Overall, Taking Flight is a humorous look at the many different flyers and ways of flying that have evolved. Look out, for example, for the insane way in which dragonflies reverse. Parikian is unapologetically enthusiastic, and the book is all the more enjoyable for it. However, for a clearer and more factual explanation of how flight works, supplementary reading will be required, and Alexander’s 2015 book On the Wing remains relevant.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Taking Flight

Other recommended books mentioned in this review:

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I have written previously that deducing behaviour of extinct animals from fossils millions of years old might seem science fiction, but is very much science fact. That said, in his previous book, English palaeontologist David Hone pointed out that dinosaur behaviour is the one area where we see the greatest disconnect between what we know and what people think we know. His new book Uncovering Dinosaur Behavior is a sobering reality check for the lay reader, but I suspect that even palaeontologists might come away wondering whether there is anything we know for sure. Concise, well-structured, and beautifully illustrated by palaeoartist Gabriel Ugueto, this is a superb book that transcends “merely” being a good popular science work by also addressing professional palaeontologists.

Uncovering Dinosaur Behavior: What They Did and How We Know, written by David Hone, published by Princeton University Press in November 2024 (hardback, 232 pages)

Uncovering Dinosaur Behavior opens with a very clear mission statement: what the book is and is not about, who it is for, and even what its potential weak points are. Hone writes about dinosaur behaviour, yes, but this is more than a catalogue of studies showing that species X likely did behaviour Y. He is aiming for a more integrated work, explaining how we figured these things out and offering advice on how to resolve conflicting results and answer remaining questions. His target audience encompasses dinosaur enthusiasts, of course, but he is additionally aiming at both palaeontologists interested in animal behaviour and ethologists interested in dinosaurs. He is upfront about the potential weaknesses: in trying to serve several masters, he might please none. Furthermore, he unapologetically follows the biases of the existing literature that emphasizes the charismatic megafauna at the expense of a broader take on dinosaurs at large. Having explicitly laid his cards on the table, Hone follows through with a logically structured book.

Three introductory chapters cater to both palaeontologists and ethologists by providing primers on dinosaurs, the fossil record, and the study of animal behaviour. You will find both a helpful appendix briefly introducing all major dinosaur lineages, and an introduction to Niko Tinbergen’s four famous questions of why an animal behaves the way it does that became the foundation for ethology. One of the chapters introduces the basic biology that both determines and limits dinosaur behaviour; topics such as activity patterns (when during the day are you active?), habitat choice, physiology, posture, and locomotion. A final important concept is extant phylogenetic bracketing, that is, looking at the behaviour of the nearest living relatives of dinosaurs (birds, crocodilians, and reptiles more widely). This will help you determine how far back in time a certain behaviour likely evolved. Armed with all of the above, you should be better able to judge whether behaviours inferred for dinosaurs are theoretically possible, plausible, or even likely.

Hone here also lays out his challenge to fellow palaeontologists to produce more rigorous science, giving you a set of eleven guidelines that he published together with Chris Faulkes in a 2014 paper. He has observed several recurrent problems with how data is used, interpreted, and presented, leading to misrepresentation and over-extrapolation of behaviour far beyond what the data supports. His philosophy is to “always favor a degree of uncertainty or lack of confidence in a result, rather than embracing an interpretation confidently that may be wrong” (p. 35).

“[The] target audience encompasses dinosaur enthusiasts, of course, but he is additionally aiming at both palaeontologists interested in animal behaviour and ethologists interested in dinosaurs.”

The remainder of the book examines five broad categories of behaviours. Given what I just wrote about Hone’s attitude to the research field, I can now explain why I introduced this book as a sobering reality check. Take the frequently depicted idea that dinosaurs lived in groups, with a certain franchise making hay out of pack hunting. Now, many animals alive today live socially, and there are advantages to doing so, but how do you deduce this from fossils? The problem with bonebeds is that fossils found in groups did not necessarily live or even die together: the taphonomic history (what happened between death and burial) matters. But equally, many groups will have lost members individually: solitary fossils do not exclude social behaviour. Trackways can similarly not be taken at face value. Beyond the challenge of assigning them to species, determining if they were laid down together is challenging, and even if they were, many interpretations are possible beyond social behaviour.

Hone is similarly circumspect when it comes to signalling and reproduction. He highlights what we know and what remains unknown. For instance, dinosaurs likely used visual and auditory signals, and they laid eggs. But did they use touch, taste, or smell? How did they mate? How many eggs did a female typically lay? What amount of care did parents bestow on offspring before and after hatching? We have data and tentative hints for some species, but for many questions, we cannot go much beyond generalities. The situation is better for combat: many species sported implements that intuitively look like weapons, but how and on whom they used them is harder to determine. Studies have furthermore focused on a small number of species while ignoring many others. Feeding biology is the area that has the most robust support, bringing together many independent lines of evidence such as biomechanics, trace fossils, isotope data, tooth microwear analysis, stomach contents, and coprolites. Even here, though, such full pictures are only available for a handful of species.

Overall, interpreting dinosaur behaviour is “profoundly difficult” (p. 152) due to both the limitations of the fossil record and the diversity and plasticity we see in the behaviour of animals alive today. The problem he observes is that “much of the scientific literature tends toward a confidence in interpreting dinosaurian behaviors that probably should not be there [while failing] to recognize alternate possibilities and the inherent uncertainty of interpreting ancient behaviors” (p. 153). That sounds pretty damning but he also recognizes that the field has come a long way from early guesswork and extrapolations to more rigorous methods that take seriously the fact that dinosaurs were once real, living animals rather than mythical monsters.

“Hone’s work […] hit the sweet spot of the kind of depth I look for in my popular academic books: fairly technical, thought-provoking, never shirking the hard questions, and yet admirably brief”

Compared to the previously reviewed The Future of Dinosaurs, which had a somewhat haphazard ordering of its chapters, Uncovering Dinosaur Behavior benefits from an excellent and logical structure that flows very well. However, some noticeable typos did slip through again, despite the extensive proofreading. All chapters come with a helpful summary and an interesting case study; I thought the one on ankylosaurs and what their tail clubs were used for was particularly compelling. I also have to praise the fantastic illustrations by Ugueto. The colour plate section is mouthwatering eye candy, and there are numerous classy and useful black-and-white drawings and diagrams throughout the book. Some of the black-and-white photos of fossils are harder to decipher, and I would not have minded had some been included in the colour plate section.

Uncovering Dinosaur Behavior was published about a year after Michael J. Benton’s Dinosaur Behavior: An Illustrated Guide, meaning Princeton University Press now has two illustrated books on this topic. Which one do you choose? In my review, I highlighted that Benton’s is an introductory book for novices that starts from first principles. Hone’s work, though very accessible, is more advanced and, for me, hit the sweet spot of the kind of depth I look for in my popular academic books: fairly technical, thought-provoking, never shirking the hard questions, and yet admirably brief at 207 pages. One thing Hone does not do is introduce and explain the various techniques. He assumes that phrases such as isotope data, palynology, and finite element analysis mean something to you and do not require more than a brief definition. If you find your eyes glazing over at these terms, maybe start with Benton’s book. For everyone else, however, Uncovering Dinosaur Behavior is a superb book that should be your go-to reference for a thoughtful appraisal of what we know about dinosaur behaviour.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Uncovering Dinosaur Behavior

Other recommended books mentioned in this review:

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The Virginia opossum is one of nature’s glorious weirdos. This North American marsupial will play dead when feeling threatened: she will fall over paralysed, eyes and mouth wide open, turn her tongue blue, drop her body temperature and heart rate, and, for good measure, drool, pee, poop, and excrete a foul-smelling green goo from her anal glands, all at the same time. “Playing” dead rather undersells it. Having just reviewed How Animals Grieve, this is the second of a two-part review exploring how animals experience and understand death, a topic studied by comparative thanatology. This young discipline sits somewhere at the intersection of ethology and comparative psychology, though associate professor Susana Monsó is instead a philosopher. With Playing Possum, she has written an exceedingly interesting book that is as accessible to a general audience as it is relevant to specialists. In the process, she convincingly argues that an understanding of death is likely very widespread in nature, but also that comparative thanatology has a whole lot of growing up to do.

Playing Possum: How Animals Understand Death, written by Susana Monsó, published by Princeton University Press in October 2024 (hardback, 272 pages)

This book was originally published in 2021 in Spanish by Plaza y Valdés Editores as La Zarigüeya de Schrödinger. Monsó translated it into English herself, in the process lightly revising the book in response to peer review, editorial feedback, and developments in her thinking. As she points out, philosophers often drive friends and family up the wall by answering every question with a “Well, it depends”. As a consequence, the first half of the book is dedicated to preliminaries before the second half gets to the heart of the question. Though this may try the patience of the general reader, I implore you to stick with it; there are two good reasons for doing so.

First is that Monsó takes nothing for granted here, systematically exploring and defining everything you need to know. She makes good use of subheadings to structure what she apologetically calls a “possibly harsh, though necessary, journey through philosophical analysis” (p. 75). The question of whether animals understand death readily divides people into two opposing camps. Monsó instead shows that the matter is much more nuanced than that and her exploration is like a fractal pattern. At every layer down, further detail and complexity are revealed, all of it relevant to the argument she is building. What three types of arguments do we have in favour of animals possessing a mind? What three methods are used to study animal minds? What are the criteria for a minimal concept of death? Why is this a valid concept? What, even, is a concept?

Without reiterating all the answers, let me get straight to her working definition. Starting from a list of seven criteria used by child developmental psychologists to gauge understanding of death, she identifies two as minimally required: non-functionality (an understanding that the dead no longer show the mental and bodily functions of the living) and irreversibility (an understanding that the dead cannot come back to life). This, she adds, is a theoretical construct rather than an empirical reality. In real life, there are good reasons to think that two other criteria are present to some extent while the remaining three are optional, and some might only be present in humans. Much like Walter Veit did for animal consciousness, she subscribes to a gradualist picture of the evolution of animal cognition. Given our complex nature, she considers humans the worst place to start analysing a question like this; far better to take a bottom-up approach.

“Monsó takes nothing for granted here, systematically exploring and defining everything you need to know.”

The second reason I admire the preliminary section of the book is Monsó’s examination and critique of comparative thanatology, showing it has a lot of growing up to do. This part is incredibly valuable to professionals as she makes explicit the discipline’s unspoken assumptions and hidden biases. One concern is that, because death in nature is unpredictable and rarely observed, the published literature mostly consists of anecdotal observations. These are prone to misinterpretation, especially when it concerns a topic as emotionally charged—to us—as death. This raises another, valid concern of anthropomorphism, i.e. attributing to animals human qualities that they do not possess. But she flags up two other equally dangerous biases that get far less attention. One is anthropectomy, i.e. denying animals human qualities that they do possess (in Mama’s Last Hug, the late Frans de Waal spoke of anthropodenial; possibly he was not aware of this term). The other bias is anthropocentrism, which takes the human experience as the universal yardstick. Where thanatology is concerned, there are two flavours that Monsó explores and disarms. Intellectual anthropomorphism means that animals are said to understand death only if they have our concept of it, overcomplicating the question. Emotional anthropomorphism means that animals are said to experience death only if they have our emotional response to it. The latter shows in the discipline’s excessive focus on studying grief. This is where Monsó circles back to How Animals Grieve and King’s insight that grief is a useful indicator of strong affective bonds, including love. But is it a good indicator of a concept of death? A useful way of seeing these two books and topics, I think, is as a Venn diagram: there is an area of overlap, but grief and death do not necessarily always co-occur.

Having thoroughly prepared the ground, in the second half of the book Monsó delves into the question of how widespread an understanding of death is in nature. Three factors that she considers instrumental readily come together in animals. Given how common death is in nature, there are plenty of opportunities for first-hand experience. This is encouraged by the wide spectrum of emotions evoked by, and directed at, the dead. Lastly, the cognition required to understand that the dead are irreversibly non-functional is fairly unsophisticated and itself important for survival: animals are keenly attuned to recognizing whether something is alive. Scientists have already done much to document how these three factors come together to various degrees to shape how different animals understand death. However, much of this has focused on a limited number of social animals such as primates, elephants, and cetaceans. Surprisingly, the relationship between violence (prominently predation) and understanding death is largely ignored in the literature. She systematically takes you through the reasons why both perpetrators and victims of violence are aware that it can be lethal, and act accordingly to inflict or avoid it.

“Monsó’s examination and critique of comparative thanatology [shows] it has a lot of growing up to do”

In an exceptionally nice flourish that brings the book full circle, Monsó ends with the titular opossum. Thanatosis, or death-feigning behaviour, is far more elaborate than it needs to be to defend oneself against predators. Instead, it reveals more about a predator’s mind. Many do not desire dead and decaying food, thus certain prey species exploit a predator’s concept of death to deceive them. The fact that thanatosis has convergently evolved in very disparate taxa is another strong indicator that “the concept of death [is] ubiquitous in the animal kingdom” (p. 205).

Monsó’s argumentation is exemplary throughout and makes the book a fascinating and accessible read for a general audience. Simultaneously, she gives a thorough examination and critique of the discipline of comparative thanatology: of its biases and presuppositions, its knowledge base and knowledge gaps. That makes the book pertinent to professionals, both thanatologists and the wider community of ethologists and animal psychologists. In my view, writing a book relevant to such a broad audience is a huge achievement. Playing Possum can be filed right next to Peña-Guzman’s recent as another example of scientists and philosophers collaborating to expand the list of biological capacities no longer exclusively human.

Both Barbara J. King and Susana Monsó were recently interviewed by the hosts of the WAMU 88.5 American University Radio show 1A as part of their Scientific Method series. You can listen to that 34-minute episode here.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Playing Possum

Other recommended books mentioned in this review:

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Death, and its attendant grief, is on that infamous shortlist of two things that are sure in life. But are humans alone in understanding death? To prepare for reviewing Susana Monsó’s new book Playing Possum: How Animals Understand Death, I reach back in time to 2013 to a highly relevant book that has been sitting on my shelf unread for too long. In How Animals Grieve, anthropologist Barbara J. King mines a compelling vein of anecdotes that strongly suggest this emotion is not uniquely human. This, then, is the first of a two-part review exploring how our evolutionary next of kin experience and understand death.

How Animals Grieve, written by Barbara J. King, published by the University of Chicago Press in April 2014 (paperback, 193 pages)

This is largely a book of stories and observations made by scientists, zookeepers, pet owners, and others who share their lives with animals. King introduces you to elephants who will seek out the bones of fallen comrades to caress and explore them with their nimble trunks. There are heartbreaking tales of dolphins keeping afloat dead calves and monkeys carrying around dead infants, to the point of corpses starting to rot and mummify. Pet owners who have had multiple cats, dogs, or rabbits widely report how survivors are affected by the loss of a companion that they have spent years with, uttering cries normally never heard or searching the house for days. Primatologists have recorded strong responses in chimpanzees and gorillas, both in captivity and the wild, to the death of fellow apes. There are touching stories here of cross-species friendships on farms and sanctuaries followed by signs of grief when one of the two partners dies. There is even the thought-provoking question of whether animals can suffer so much that they are driven to suicide. How Animals Grieve flows over with stories that will tug at your heartstrings.

Now, a hard-nosed sceptic might just see a collection of unlikely stories here but I am reminded of what Carl Safina wrote in Beyond Words: how his mental bin labelled “unlikely stories” is getting cluttered. You can only ignore a steady piling up of anecdotal observations for so long. King, while moved by these stories, keeps her composure and examines the matter with the eyes of a scientist. There are noticeable commonalities when a companion dies: distress, loss of appetite and weight, a lacklustre or dejected attitude with a loss of interest in one’s environment, acting out, displays of aggression, etc. Animals of many stripes show such behaviours. An initial and, by her admission, not completely perfect definition of animal grief hinges on two ingredients. First is love as evidenced by a strong drive to be close to each other. Second is the suffering that follows when animals can no longer be together. We cannot always observe separation in the wild, and this definition does not distinguish between different kinds of love, but her starting point is that: “When we find animal grief, we are likely to find animal love, and vice versa. It’s as if the two share emotional borders” (p. 10).

“{King’s] starting point is that: “When we find animal grief, we are likely to find animal love, and vice versa. It’s as if the two share emotional borders” (p. 10).”

Particularly interesting is the neurobiological work on animal grief that King discusses here. The authors of a 2011 study looked at the biology of depression and observed that stress has a neurophysiological impact, leading to brain damage. The resultant inflammatory response to repair it leads to psychological pain. Is this what we experience as grief? King quotes one of the authors who summarises their findings thus: “Grief is an evolved behavioral program, akin to sickness behavior, that promotes convalescence during a significant neural rewriting job” (p. 50). It responds to earlier work by John Archer who in The Nature of Grief instead argued that grief might be evolutionarily maladaptive but also an unavoidable corollary of a more useful separation response that drives individuals to reunite when separated. I have to admit that Archer’s explanation appeals as well and reminds me of what Justin Gregg wrote about human morality (and its failings) in If Nietzsche Were a Narwhal: “You cannot have that laundry list of positive cognitive skills without the negative consequences” (p. 154 therein).

King admits that not all examples she discusses here are airtight. When we move away from primates and other social mammals, gauging what is going on becomes harder. Do intelligent birds such as corvids grieve? Marzluff & Angell think they do, but probably not for very long. And what about sea turtles? Hawai’ian locals who in 2008 erected a memorial for a slaughtered turtle observed a male visiting it and sticking around for hours. King admits it is hard to know what was going on here, despite the spin immediately put on it by media reports. Some cases may seem far-fetched but I am reminded of Safina’s pithy conclusion in Beyond Words about how humans and other animals are all shaped by the same evolutionary forces: “beneath the skin, kin” (p. 324 therein). We are all built on the same meat-and-bones platform, running on the same bio-logic, if you will. This is an area ripe for further study and drives home a point King makes midway through the book: “We won’t have a hope of finding […] grief until we look for it” (p. 105).

“though death and grief often co-occur, they do not have to […] not grieving is not equal to not understanding death.”

There are three take-home messages for me in this book that I want to call out. First, King early on highlights that, though death and grief often co-occur, they do not have to. Grief does not require “a cognitive mastering of the concept of death” (p. 14) and not grieving is not equal to not understanding death. This distinction will be particularly relevant when we next turn to Monsó’s book Playing Possum. However, King muddies the water somewhat: despite this caveat, she almost exclusively discusses grief in the context of death, with other contexts only given incidental mention and not explicitly examined. It could well be that such data were simply not available at the time of writing because of the anthropocentric biases in what researchers choose to study, as Monsó would later highlight. If so, King does not comment on it, nor call for researchers to examine grief in other contexts.

Second, and tying in with this, is how King highlights both intra- and interspecific variation in grief. Intraspecific variation means that not all individuals of a species will express grief, though that for King does not negate the phenomenon at large. I would argue that the distinction the late Frans de Waal made between emotions (observable bodily and mental states) and feelings (subjective internal states) offers another useful way of thinking about this. Furthermore, especially in primates, we have clear examples of individuals showing different responses to death: aggressive displays, touching (or not) of the body, and avoidance (or not) of the room where the companion died. Interspecific variation means that there is no universal way of grieving across species: “Goat grief […] is not chicken grief […] is not chimpanzee grief or elephant grief or human grief” (p. 7). As an anthropologist, she thinks humans are exceptional in being able to anticipate future grief when someone falls ill, sometimes months or years ahead of time. However, acknowledging such differences “need not amount to a manifesto of human superiority” (p. 147). Asking whether our grief is deeper than that of other animals misses the point for her: “We each are what we are, animals bound together by our various ways of grieving” (p. 148).

“Interspecific variation means that there is no universal way of grieving across species […] Asking whether our grief is deeper than that of other animals misses the point”

Third, the study of animal grief has value for anthropology. We have scattered evidence of purposeful burials as far back into prehistory as approximately 100,000 years ago and possibly older, but were these accompanied by grief and mourning? Excavations, grave-good inventories, bone analyses etc. cannot answer this question, but the body of observations discussed here can help, suggesting that grief has deep evolutionary roots. King is quick to qualify this: “It is only emotional capacity that this comparative context illuminates, though, and we would do well to keep in mind that the capacity to experience an emotion doesn’t always result in the expression of that emotion” (p. 159).

How Animals Grieve is a compelling and thought-provoking book. To my mind, King leaves little doubt that we are not alone in experiencing grief, even if the details differ between species. The consequences of what that means for how we treat animals are only all too briefly explored here, beyond her acknowledgement that we are often the cause of animal grief. If books by Carl Safina, Frans de Waal, or Marc Bekoff resonate with you, this book will too. Finally, what can all this tell us about animals’ understanding of death? I will next turn to Monsó’s book Playing Possum where we will see a thorough philosophical analysis of this question.

Both Barbara J. King and Susana Monsó were recently interviewed by the hosts of the WAMU 88.5 American University Radio show 1A as part of their Scientific Method series. You can listen to that 34-minute episode here.

How Animals Grieve

Other recommended books mentioned in this review:

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In 2016, scuba-diving philosopher Peter Godfrey-Smith made a huge splash with his book Other Minds in which he explored the evolutionary origins of a mind quite unlike ours, that of the octopus. In 2020, he followed this up with the altogether more cerebral Metazoa in which he explored the evolution of animal minds more broadly. I reviewed both books favourably. Now, another four years later, Living on Earth is presented retrospectively as the conclusion to this trilogy exploring the origins of intelligence. In a book that is never less than thoughtful, Godfrey-Smith examines how life shapes, and has been shaped by, its environment.

Living on Earth: Life, Consciousness and the Making of the Natural World, written by Peter Godfrey-Smith, published in Europe by William Collins (a HarperCollins imprint) in August 2024 (hardback, 323 pages)

Godfrey-Smith tackles the above theme in three parts. Before delving in, his first chapter provides an additional evocative angle on what he wants to examine: “The history of life is not just a series of new creatures appearing on the stage; the new arrivals change the stage itself” (pp. 6–7). Through their actions, organisms modify their environment and, in more formal terms, he considers “organisms as causes, rather than evolutionary products” (p. 7). To my surprise, despite the fascinating concept, Living on Earth did not impress me as much as the previous two books. In part, the bar has been put so high that I went in with elevated expectations; in part, it wanders quite widely into subjects that seem only tangentially related to its core theme. Below, I will describe the book’s three parts and try to substantiate why it did not sweep me off my feet the way its predecessors did.

The first part explores the life-as-cause angle best, I felt. Three chapters cover some of the important steps in the history of life, such as the evolution of photosynthesis and how it flooded the atmosphere with oxygen, multicellularity, and how plants shaped the terrestrial world and life on it. Earth’s biography has been told by many writers and Godfrey-Smith’s aim is not to give a rundown of all the major transitions in evolution. To be honest, I was expecting the book to go full-bore on the conceptual side of life-environment coevolution as there are many fascinating and still controversial topics here. A relevant concept such as niche construction now only features briefly, and while he covers culture, other mechanisms by which the environment can influence heredity, such as epigenetics, are omitted from his story.

“Godfrey-Smith examines how life shapes, and has been shaped by, its environment. […] In more formal terms, he considers “organisms as causes, rather than evolutionary products” (p. 7).”

Instead, Godfrey-Smith has a slightly different plan. In the second part, he turns his attention to the human mind with two chapters that are grab bags of topics centred on culture and consciousness. He considers culture in the broad sense of non-genetically transmitted behaviours such as tools, language, and writing. Regarding consciousness, he argues this is widespread in animals and evolved gradually (Walter Veit, acknowledging his influence, recently proposed a detailed sequence of events). Godfrey-Smith prefers the term “felt experience” instead of consciousness, and in a beautifully concise turn of phrase describes animals as “a nexus in which sensing and action meet, with a mass of causal lines coming in and radiating out” (p. 158). This creates a system that has a point of view, “a system that is a “whom”” (p. 158). The third part changes tack again. Given that human minds evolved and are proving to be an Earth-shaping force, should we act differently towards our environment and, if so, how? Using several ethical theories as guidance, he tackles animal welfare in farming and experiments, climate change, and conservation.

On the back of this very brief outline of the book’s structure and topics, I have three closely intertwined observations. First, as already mentioned, the book meanders a fair amount. In his first chapter, Godfrey-Smith describes Living on Earth in arboreal terms and calls it a forest book: from the main stem, many topics branch off and will be explored. This seems particularly apparent in the second part of the book. He discusses, for example, how and at what cost humans transitioned from a nomadic hunter-gatherer existence to settled societies (in the process giving nods to both Graeber & Wengrow and James Scott). Another example is how he delves into the nature of nervous systems, how they are about more than connectivity between neurons but also display large-scale electrical patterns, and what this means for attempts to replicate brains artificially. These and various other topics are all captivatingly presented but sometimes feel like tangents that lead the reader quite far from the core theme of life-environment coevolution.

“Godfrey-Smith is never less than thoughtful. Ideas are given serious consideration and nothing is discarded out of hand.”

Second, and in part explaining the first observation, is that Godfrey-Smith is never less than thoughtful. Ideas are given serious consideration and nothing is discarded out of hand. For example, addressing James Lovelock’s Gaia hypothesis is unavoidable given the core theme of Living on Earth. Since I did a deep dive on this topic, I was very interested to read his sceptical but fair assessment that raises some of the same objections Tyrrell also raised in On Gaia. Another example is how he spends several pages on the rather curious observation of inter-brain synchrony. Simultaneous brain scans of multiple people (so-called hyperscanning) have shown that large-scale electrical oscillations in brains can synchronize (to an extent) during cooperative tasks. This is a very controversial area of research that has its roots in 1960s attempts to demonstrate telepathy and extrasensory perception (ESP). He is sceptical but does not want to immediately dismiss these observations.

Third, this is his most personal book to date. By carefully exploring ethical quandaries using different frameworks, Godfrey-Smith explains his views on thorny subjects. For example, why does he oppose factory farming? Rather than turning to utilitarianism (do the benefits outweigh the drawbacks?) or Kantian ethics (are we respecting the preferences of others?), he proposes a framework of “a life worth living”. The admittedly imperfect but useful litmus test is whether, after considering an animal’s whole life, you still would want to reincarnate as one. Another example is his view on conservation. He rightfully points out that climate change is dominating environmental discourse, and then goes on an extended discussion of whether, why, and how we should protect wild nature. After pointing out how it gave rise to all lifeforms on Earth, he concludes that “there’s a kind of ingratitude in allowing the extinctions, the narrowing, the reduction of animal life. I am proposing that we take some responsibility for this creative engine, and value its continuation” (p. 248).

In his acknowledgements, Godfrey-Smith writes how “a book about octopuses led to a book about nearly everything” (p. 305) and Living on Earth is indeed easily the most ambitious of the three. The writing remains as accessible as ever, despite venturing into technical areas such as neurobiology, ethics, and philosophy. Nevertheless, I found I had to reset my expectations after the previous two books and was thrown a bit by it being a somewhat less focused affair. In covering so much ground, this is a book that might not offer readers instant gratification; rather, this is a journey that requires some patience. The trip is worth it, however; when Godfrey-Smith leads you to a certain vantage point on a topic, the view can be sublime.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Living on Earth

Other recommended books mentioned in this review:

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This is the third of a trio of reviews in which I take a brief detour into ants and collective behaviour more generally. I previously reviewed The Ant Collective, a graphical introduction to ant behaviour, and entomologist Deborah M. Gordon’s Ant Encounters, a primer on how collective behaviour in ants comes about. The Ecology of Collective Behavior is the second book by Gordon that I will examine. It proposes a research programme to figure out both how collective behaviour responds to changing environmental conditions, and how it evolves. Though squarely aimed at professional biologists, this brief and interesting book is nevertheless accessible to a wider interested audience and makes its case with nary an equation in sight.

The Ecology of Collective Behavior, written by Deborah M. Gordon, published by Princeton University Press in October 2023 (paperback, 184 pages)

One of the most familiar examples of collective behaviour is swarming, where large numbers of animals move in a coordinated fashion, whether flocks of birds or schools of fish. However, collective behaviour can take many different forms and it has proven incredibly tricky to develop a general theory that successfully captures the diversity of processes generating it. As far as Gordon is concerned, one habit of thought that is holding us back is reductionism: “it is not possible to learn how natural systems function collectively by considering the components separately and independently of the world they inhabit [as it] severs the relations that matter” (p. 2).

A brief tangent here, as the limitations of reductionism have been a recurrent theme in recent reviews. Gordon’s book thematically sits smack in the middle of several others I have covered lately. Safina made exactly this observation (that reductionism overlooks relational dynamics) in Alfie & Me. Also, this is the second book in short order that mentions panta rhei (“everything flows”) and refers to Nicholson & Dupré’s book. But where I gave Slijepcevic’s Biocivilisations a mixed review for, amongst others, dunking on reductionism, Gordon is intellectually honest enough to admit that without centuries of reductionist research: “we could not have arrived at the recognition that all of this knowledge is not enough” (p. 34). Her book is far more grounded and presents an actionable framework.

Gordon’s goal here is to outline how she researches collective behaviour. She is particularly interested in how it changes in response to changing environments because, again, panta rhei: “response to changing conditions is fundamental in living systems” (p. 5). You start to see why studying this can be quite challenging as you are effectively considering second-order dynamics (the dynamics of dynamic behaviour). The book’s nine chapters break down into roughly three parts that I will discuss further below.

“There is an interesting discussion here as to why attempts at formulating an overarching theory [of collective behaviour] have failed.”

Chapters 2 to 4 form an introduction to the topic. Gordon describes the two model species that she has worked on for several decades: the desert-dwelling red harvester ant Pogonomyrmex barbatus and the rainforest-dwelling turtle ant Cephalotes goniodontus. Their collective behaviour differs and, as later chapters explore, this can be linked to differences in their environment. She then zooms out to consider collective behaviour more generally, whether at the level of molecules, cells, or organisms, and discusses two well-studied examples. Lastly, she considers how collective behaviour results from individual interactions and reflects on that buzzword “emergence”. A younger Gordon was once a fan; today she is ready “to replace its mystical glow with something more substantial” (p. 33). There is an interesting discussion here as to why attempts at formulating an overarching theory have failed: similar outcomes do not necessarily result from similar processes; model output resembling what we see in nature does not necessarily mean that you have identified the processes at work; and models that fail to predict an outcome can be incomplete rather than incorrect, since the same process can have different outcomes under different conditions.

The next two chapters present her core framework that explains how collective behaviour depends on, and responds to, environmental dynamics. To reiterate: collective behaviour consists of individuals interacting with each other. She considers three parameters of collective behaviour: rate (fast/slow: how quickly interactions respond to environmental change), feedback (stimulation/inhibition: how interactions change the collective behaviour), and modularity (uniform/modular: a description of network structure in terms of node connectivity, i.e. are all individuals in contact with each other or do they form distinct, internally connected clusters). She then links these three behavioural parameters to three environmental parameters: stability (stable/unstable: how prone the environment is to large or frequent changes), resource distribution (patchy/uniform: how resources are distributed in time and space), and energy flow (low/high: the ratio of energy or resources obtained versus spent; economists also speak of EROI: energy return on investment).

These two sets of three parameters relate to each other as follows, as exemplified by the ant species she studies. Rate depends on stability and resource distribution. Harvester ants live in stable desert environments with uniformly distributed resources and adjust their foraging activity slowly. Turtle ants live in the exuberant chaos of a rainforest where they form rapidly changing foraging trails to exploit ephemeral resources. Feedback depends on stability and energy flow. For harvester ants, foraging is energetically expensive and they need stimulation (positive feedback) from patrollers before they leave the nest. For turtle ants, foraging is energetically cheaper and they will continue to forage until inhibited (negative feedback) by e.g. a shortage of mouths to receive the liquid food they carry home. Modularity (like rate) depends on stability and resource distribution. In harvester ants, modularity is low and individuals are highly connected with information transfer happening in a centralized fashion in the nest. In turtle ants, modularity is high, with foraging decisions resolved locally through interactions of small groups of ants. If the above all seems rather impenetrable, that will be my attempt to condense her framework into just two paragraphs. Fortunately, her treatment of it is more accessible: she presents it as a verbal argument and pads it out with lists of examples from across the biological spectrum. Having quickly perused the copy I have here, those interested in a mathematical treatment of collective behaviour should instead turn to Sumpter’s book Collective Animal Behavior.

“The emphasis on an actionable framework illustrated by her decades-long research on ants makes for a particularly grounded, can-do book.”

The third part, then, wraps up the discussion. One chapter provides a very practical research programme for investigating how collective behaviour works: observation followed by experimental disruption. There are some excellent tips here on how to disrupt a system (stay within the ordinary range of fluctuations) which she contrasts with other standard approaches such as knockout experiments and factorial design. She illustrates her approach by taking the reader through decades of her research on harvester ants.

The last two chapters consider the evolution of collective behaviour. In some ways, this is little provocative: participation in collective behaviour is an aspect of an organism’s phenotype and thus a trait subject to natural selection, just like any other trait. Where it gets more provocative (depending on your viewpoint) is that, as a pupil of Richard Lewontin, she embraces the Extended Synthesis, including environments (in addition to genes) influencing phenotypic expression, organisms altering their environment (niche construction), and the always hotly debated notion of group selection. I am receptive to these ideas and hope to explore them more in future reading. Gordon offers interesting critiques here of divisions such as nature/nurture and (in ethology) instinct/learning and how they are holding back our understanding of collective behaviour. Particularly insightful is the last chapter that contrasts her framework with the prevailing idea that collective behaviour is marked by a conflict of interest between the individual and the group, i.e. that strategic individuals always seek to maximize fitness and prioritize individual benefits over the collective good. If I understand her correctly, she argues that, because collective behaviour has consequences for individuals, selection can act on how individuals produce collective behaviour. In other words, selection can act on multiple levels simultaneously, without group selection necessarily conflicting with individual selection.

Are there limitations to Gordon’s ideas? She indeed expects that her hypotheses will not cover all possible ways that collective behaviour can interact with a changing environment. Chapter 5 explicitly opens by writing that “these hypotheses are meant as a framework for research on collective behavior, not as a deductive theory” (p. 46). Though this book is aimed at biologists studying collective behaviour, the subject matter here is easily accessible to ecologists and evolutionary biologists more generally. The verbal argumentation and numerous examples also put this book within reach of interested general readers. The emphasis on an actionable framework illustrated by her decades-long research on ants makes for a particularly grounded, can-do book. Overall, a very interesting perspective and a satisfying conclusion (for now) to my brief detour into collective behaviour in ants.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

The Ecology of Collective Behavior

Other recommended books mentioned in this review:

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This is the second of a trio of reviews in which I take a brief detour into ants and collective behaviour more generally. I previously reviewed The Ant Collective, a graphical introduction to ant behaviour, and am here turning to entomologist Deborah M. Gordon’s 2010 book Ant Encounters before finishing with her recent book The Ecology of Collective Behavior. The core question driving this book is how ant colonies get anything done given that no one is in charge. Her contention, supported by a wide-ranging survey of examples, is that ant colonies function through numerous ants interacting to form a dynamic network. Stated this pithily, I admit it might not sound like much of an answer but rather a rephrasing of the question using fancy words. What do you mean, “interaction network”? If so, read on: this primer is full of fascinating biological examples and interesting insights that will hopefully clarify the above, providing you with a bigger picture of how and why ants behave the way they do.

Ant Encounters: Interaction Networks and Colony Behavior, written by Deborah M. Gordon, published by Princeton University Press in April 2010 (paperback, 167 pages)

A brief tangent to get started. Ant Encounters was the first in the then-new series Primers in Complex Systems, produced by the Santa Fe Institute in New Mexico. This is a think tank that studies complex systems in, amongst others, biology, physics, sociology, and computer sciences. Next to a small cadre of resident researchers, they host a rotating cast of visiting academics and provide an environment for cross-disciplinary research, discussion, and exchange of ideas. Some other books I have reviewed here have been the product of, or at least been helped along by, time spent here. Seven books have been published so far in this series, though there have been no new additions since 2019. If this first book sets the tone, these are very interesting and accessible little books that are worth checking out and I have listed them below. Anyway, back to Gordon and ants.

This book follows her popular book Ants at Work published another decade earlier in 1999. At the time of writing Ant Encounters, Gordon had already been studying ants for some three decades, since the early 1980s, mostly the desert-dwelling red harvester ant Pogonomyrmex barbatus. Her work and ideas formed in response to the then-prevailing view that ants are effectively genetically programmed to perform particular tasks. Her early work instead found that what ants do depends on interactions with other ants, which in turn can modify their environment, which in turn can feed back on subsequent interactions, etc. In other words, the behaviour of colonies arises from dynamical, constantly shifting networks of interactions. (The Ant Collective neatly showed in pictures how this works in the waxing and waning of a foraging trail.) After introducing this concept in the first chapter, the remaining six chapters flesh it out with numerous examples at different levels of biological organization.

A logical first question to ask is what ants actually do when they meet. A lot of feeling each other up is what. Communication in ants is firstly tactile, with ants using their antennae to touch each other (entomologists speak of antennation). One of Gordon’s key points is that “the pattern of interaction itself, rather than any signal transferred, acts as the message” (pp. 47–48). Experiments in harvester ants showed that what stimulated foragers to leave the nest was the encounter rate with patrollers returning in the morning. One question for Gordon I was left with was whether smell acts as a message. After all, a second important channel is chemical, with ants, like many other insects, carrying hydrocarbons (so-called cuticular hydrocarbons) on their exterior. These serve as an identity badge but also change during tasks: Gordon’s work on harvester ants showed how ant odour changes as they go outside e.g. to forage. Interestingly, there is individual variation in how active ants are but this is not fixed. Remove particularly active ants and others will take up their workload; there are no “forager heroines” (p. 66).

“A logical first question to ask is what ants actually do when they meet. A lot of feeling each other up is what. […] One of Gordon’s key points is that “the pattern of interaction itself […] acts as the message“”

Scaling up a little to the level of local interactions, Gordon objects to the idea of “division of labour” introduced by famed entomological titan E.O. Wilson. He happened to study some of the few ant species where workers have different body sizes and tried to demonstrate that there was a caste system with size-based task specialisation. Though partially successful, even here individual behaviour changes as needed, with e.g. removal of minors (small ants) causing larger majors to switch to brood care. More importantly, Gordon adds, in most ant species workers are of similar size. Whereas “division of labour” implies static procedures and permanently assigned roles, her preferred term “task allocation” highlights the dynamic, flexible nature of ant behaviour. A related idea that is scrutinized is age polyethism: tasks changing as a function of age. I encountered this in Tschinkel’s book Ant Architecture and though young ants are indeed born in the depths of the nest, the idea that they move up with age and get “promoted” to brood care, nest construction, and finally foraging is more often proposed than backed up with data in the published literature. Experiments on carpenter ants showed that if one age group was removed, others would take over their tasks, suggesting that colony needs override ant age.

Speaking of age, colonies are not static entities and, though there are very few studies on this, colony growth influences behaviour. Particularly important are ant-plant interactions with ants defending host plants from herbivores, thus stimulating plant growth, which in turn begets a larger colony (a nice example of niche construction if ever there was one). In many such mutualisms, there is a third party such as scale insects or aphids that feed by sucking a plant’s sap but are vulnerable to predators. Ants protect them in exchange for the sugary honeydew these sap-suckers excrete from their anuses. The plants tolerate the sap-suckers because the ants thus attracted protect against more harmful herbivores. Ecologist Robert May is quoted as describing such three-way interactions as “an orgy of mutual benefaction” (p. 124).

Scaling up further brings Gordon to the level of inter-colony interactions, both conspecific (between colonies of the same species) and heterospecific (between colonies of different species). Interactions are both direct, e.g. encounter rate with neighbours indicating the size of their colony, and indirect, e.g. competition for food being a zero-sum game: what one colony eats is not available to the other. Bar some spectacular exceptions, fighting between conspecifics is usually avoided. In response to neighbourly interactions, harvester ant patrollers will redirect the next day’s foraging trails. When it comes to heterospecific interactions, conflict has been better studied and Gordon highlights the rise of invasive ant species in the last three decades as another opportunity to do so. In general, numerical advantage trumps body size, with small-bodied species capable of simply swarming larger-bodied ones. A further, delightful level of interaction is between ants and the organisms living in their midst (so-called myrmecophiles) that I discussed at length when reviewing The Guests of Ants.

“In many ant-plant interactions, there is a third party involved, such as scale insects or aphids, in what has been described as “an orgy of mutual benefaction“”

The final level Gordon considers is that of evolution. How did colony organization evolve from ancestors that did not live in colonies? In particular, as workers are unable to reproduce, how did worker sterility evolve? W.D. Hamilton linked it to the haplodiploid mating system of ants where males hatch from unfertilized eggs and carry a single set of chromosomes (haploidy) while females hatch from fertilized eggs and carry the regular two sets of chromosomes (diploidy). One quirk of this system is that, if a queen mates with only a single male, females are more related to their sisters than to their daughters, with kin selection maintaining worker sterility once it somehow arises. The fly in the ointment that Gordon points out is that many queens mate with several males, so Hamilton’s maths quickly unravels, leaving the mystery of worker sterility intact. (In Endless Forms, Sumner explores this story more in-depth, showing there are other reasons why Hamilton’s explanation does not work). What we do know is that ants evolved from vespoid wasps, themselves a case study in the evolution of sociality. Interestingly, worker sterility has evolved many times in wasps and shows more flexibility, with wasps able to become egg layers when needed, arguing against a sudden mutation being responsible for worker sterility in ants. The matter remains unresolved, but Gordon does think that describing social structure in terms of who lays the eggs is “misleading language [that] equates the allocation of egg-laying with social organization and directs attention away from everything else that makes up the diverse and complex social organization of ant colonies” (pp. 130–131).

If all of the above left your head spinning somewhat, then you are not alone. There are some really interesting challenges to established ideas in this slim book, but it took some effort to distil these key points. Much as was the case for The Guests of Ants, this book presents a bewildering variety of examples from many different species, reflecting the state of play in myrmecology. A recurrent theme is that we have extremely limited data. Of the approximately 11,000 ant species known to exist, only 50-odd have been studied in any detail and even then only in fragmentary fashion. “What we have so far are only some of the pieces of many different puzzles; fragments of the picture for army ants, other pieces for harvester ants, others still for fire ants, and so on” (p. 144). Even in this limited sample, exceptions and diversity abound. A brief final chapter considers what it would take to construct models of ant behaviour. This would come to occupy Gordon for the next decade, resulting in the recent publication of The Ecology of Collective Behavior to which I will turn next.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Ant Encounters

Other recommended books mentioned in this review:

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Princeton’s Primers in Complex Systems:

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This is the second of a three-part review on acoustic communication in animals. Zoologist Arik Kershenbaum impressed me with the previously reviewed The Zoologist’s Guide to the Galaxy. That popular work on astrobiology was a diversion from his actual research on vocal communication in animals. Rather than asking what animals are saying, Kershenbaum is foremost interested in why animals talk in the first place. How do they live, what do they need to say to each other, and are there any parallels with human language? The answers Kershenbaum presents are a highly stimulating and thought-provoking exercise in decentering the human experience and trying to understand animals on their terms.

Why Animals Talk: The New Science of Animal Communication, written by Arik Kershenbaum, published in Europe by Viking Books in January 2024 (hardback, 273 pages)

Obviously, animals communicate via many more channels than just sound and Kershenbaum happily admits that each of these is worthy of their own book. He focuses on vocal communication both because sound is a very useful medium, and because it interests us as a vocal species ourselves. He further narrows down his approach by discussing six animal species: wolves, dolphins (the subject of many misconceptions), parrots, hyraxes (which look like rodents but are related to elephants), gibbons, and chimpanzees. As alluded to above, the core idea propelling this book is that “why animals need to talk is the important question to ask before we can answer how and what animals are saying” (p. 14). What these six species share is that they are highly social and negotiate their social environment using complex communication. Though Kershenbaum promises to put the animals first and the science second, I found his take on the science to make for a particularly captivating book. How so? Well…

First, he stresses the importance of studying animals in the wild, in the natural environment they evolved in. This is hard and time-consuming work and the literature on e.g. hyraxes and gibbons is rather limited, while that on wolves risks being biased by the preponderance of research done in Yellowstone National Park. Our knowledge of parrots is coloured by their popularity as pets, whereas their communal lives in the wild are rather different. Only chimpanzees can be said to be intensively studied in the wild. Kershenbaum’s conviction is that “we can’t understand animal communication without understanding animal societies” (p. 10). Each chapter therefore furnishes you with the basics of their communication—the howls of wolves, the whistles of dolphins, the squawks and whistles of parrots, the multisyllabic songs of hyraxes and gibbons, and the many grunts and hoots of chimpanzees—and how these grease the wheels of their social interactions.

“the core idea propelling this book is that “why animals need to talk is the important question to ask before we can answer how and what animals are saying” (p. 14).”

Closely related to this is the question of what can be learned from the various attempts at teaching animals human language, such as Irene Pepperberg’s work with the African grey parrot , dogs such as Chaser, or decades of experiments with primates. Though some animals show impressive linguistic capabilities, the amount of training required is often extraordinary. The conceptual flaw with such research is that you are training animals to understand human words, ultimately revealing more about our than their language. In the chapter on dolphins, Kershenbaum pointedly asks: “Why should dolphins have a language just like ours? Are human languages really the template for the way that animal communication must work?” (p. 75).

This brings me to the idea that I consider to be the showstopper of the book. To really understand animal communication means kissing goodbye to the human-centric notion of words. “Just because we’ve developed a language based on distinct words doesn’t mean that is how others must communicate” (p. 74). Kershenbaum hammers home this message explicitly in the chapters on wolves, dolphins, hyraxes, and gibbons. What these species share is that there rarely is a one-to-one relationship between a sound and a concept. Even alarm calls warning of predators vary in some species. The six animals explored here use vocal communication to “relate to emotional states, rather than intellectual ones” (p. 241). Thus, there is no dictionary to draw up, no key or cypher to find to “crack the code”. He is sceptical of recent attempts that throw deep-learning algorithms, neural networks, or artificial intelligence at the problem. We should focus on understanding the animals first, “rather than hoping for human-like information, and searching doggedly for what we want to find” (p. 77). Wrapping your head around this one is an exercise in decentering the human experience.

“To really understand animal communication means kissing goodbye to the human-centric notion of words.”

It should be evident by now that there is an anti-anthropocentric streak running through this book. But next to the usual “humans are not the pinnacle of evolution” sentiment espoused by biologists, he also objects to the idea that animals converse with each other like humans but in their own languages. This is just anthropocentrism in reverse that still takes the human experience as the universal yardstick. Kershenbaum instead explodes the idea: animals do not have human-like language because they have no need to. “Nothing about the behaviour of wolves or dolphins or even humpbacks gives any indication that having a language like ours would be useful to them” (p. 243). While this may sound controversial, examining the details of their lives reveals that, compared to the open-ended language of humans, “the amount of information they need to convey to each other is, in most cases, limited” (p. 235). Though we find elements of linguistic ability scattered all over the animal world, no other species combines these as we do. Kershenbaum admits that human language^[1] really does seem to be unique, or rather uniquely weird. “It’s almost as if words were an afterthought, an embellishment on communication. Unnecessary glitter attached to the ordinary kind of signals that animals send to each other all the time” (p. 219). I am going to invoke what I wrote elsewhere about Justin Gregg’s book If Nietzsche Were a Narwhal. Rather than concluding that human-like language does not readily evolve, maybe we should conclude that it readily does not evolve. Gregg argued along the same lines when he concluded that most animals seem to be getting by just fine without evolving human-like intelligence.

Whereas the previously reviewed The Voices of Nature wandered widely through the noisy realms of bioacoustics and suffered slightly in its organisation, Why Animals Talk is a more focused affair that organises its contents in each chapter with helpful subheadings. Mathevon only touched on the question of whether animals have a language in his final chapter, making this the perfect follow-up. While the biological details are interesting by themselves, what elevates this book is how Kershenbaum forces you to rethink linguistic concepts you have always taken for granted so that you may understand animals on their terms, not ours. In the process, he throws out as many unanswered questions as he provides insightful answers to others. Needless to say, I found Why Animals Talk to be an incredibly captivating and stimulating book.

Of course, discussing acoustic communication in animals would not be complete without considering humans. Join me as I next turn to Shane O’Mara’s Talking Heads.

1. ↑ Some readers might be frustrated by Kershenbaum’s refusal to provide a formal definition of language. This is not an oversight, but a conscious decision that he defends by pointing out the lack of a universally agreed-upon definition.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Why Animals Talk

Other recommended books mentioned in this review:

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On account of our good eyesight, humans are said to be a visual species. However, when you stop and think about it, human language (at least English) has a surprisingly large vocabulary for the squawks, grunts, chirps, honks, growls, etc. that other animals make. What, if anything, are they saying? Two recent books delve into this question, The Voices of Nature and Why Animals Talk. A last-minute entry on human language, Talking Heads, turns this into a three-part review. In other words, we need to talk…

The Voices of Nature: How and Why Animals Communicate, written by Nicolas Mathevon, published by Princeton University Press in August 2023 (hardback, 375 pages)

This book was originally published in French in 2021 as Les Animaux Parlent: Sachons les Écouter by HumenSciences who also translated it into English. Their translation leaves intact the character of the book, including frequent exhortations aimed at the reader that somehow feel very French to me. None other than ecoacoustics legend Bernie Krause contributes a foreword. Author Nicolas Mathevon is currently a professor of neuroscience and animal behaviour at the University of Saint-Etienne. For over three decades, he has focused on bioacoustics, the study of animal and human acoustic communication, and from 2017 to 2023 he was president of the International Bioacoustics Society.

The Voices of Nature gives a wide-ranging overview of current themes and questions in the field, as well as a first-hand account of the laboratory research and fieldwork Mathevon and his colleagues have been getting up to. He opens, sensibly, with an introduction to Nikolaas Tinbergen’s four questions that motivate ethological research, as well as the basic physics of acoustics. The book-proper covers a plethora of topics of which I can only discuss a few examples in more detail.

Anybody who has ever watched a documentary on nesting seabirds might wonder: how do parents relocate their chicks amidst the incessant din of dense breeding colonies? This touches on the more general question of how communication works against a background of noise. Mathevon describes how biologists have adopted Claude Shannon‘s mathematical theory of communication. Originally aimed at limiting the impact of noise on telecommunication signals, it proposes three strategies that are also adopted by animals. One, increase information redundancy by repeating your message. Research on king penguins shows a linear relationship between wind speed (and thus noise) and how often they repeat their multisyllabic calls. Two, increase signal strength by talking louder and, three, change frequency to avoid noise-filled channels. Both of these are famously observed in birds singing both louder and at a higher pitch in urban environments, but acoustic adaptations to human noise are widespread.

“how do [nesting seabirds] relocate their chicks amidst the incessant din of dense breeding colonies? This touches on the more general question of how communication works against a background of noise.”

Another particularly interesting chapter deals with the evolution of communication, discussing two models of how signals evolve. The precursor sender model is a case of exaptation: existing behaviours or structures are turned into new communication signals. For example fish, that, in the absence of vocal cords, turn their swim bladder into a vibrating sound box. The sensory bias model proposes that senders exploit a sensitivity in the receiver. For example, female crickets freeze in response to high-pitched bat calls. Male crickets have started to exploit this by emitting their own high-pitched calls, making it easier to locate females. Next, the huge diversity of acoustic signals in nature can be explained by a plethora of mechanisms: sexual selection, kin selection, ecological selection, etc. Sometimes, however, it is a side-effect of other evolutionary scenarios. You are familiar with the adaptive radiation of Darwin’s finches that resulted in species with different beak shapes. But did you know that this affected their songs as well? Larger-beaked species have simpler songs as their muscles simply cannot move their beaks fast enough to produce the sorts of rapid modulations heard in smaller-beaked species.

A final interesting topic was already touched on in my previous review of Of Cockroaches and Crickets: ecoacoustics. Mathevon profiles Bernie Krause who has spent decades recording environmental soundscapes and is one of the pioneers of the discipline of ecoacoustics or soundscape ecology. Rather than listening to the vocalisations of one species, he has been listening to the totality of our world’s sound as produced by (non)human animals and natural forces (its biophony, anthropophony, and geophony). He has convincingly shown how these soundscapes are a measure of ecosystem health and are increasingly simplifying, changing, and disappearing due to human encroachment. Mathevon discusses some of the theoretical underpinnings of Krause’s idea of how and why soundscapes are structured. First is the acoustic niche hypothesis. Look at a soundscape spectrogram and you will notice how animals vocalize at different pitches, avoiding overlap. You can cut that pie in many different ways though. Acoustic overlap can also be avoided by being active at different times, or, where species do overlap, by unique rhythms. A second hypothesis is that of acoustic adaptation: the idea that sound signals are optimized for transmission in an animal’s habitat. Experimental support for this is mixed, and it seems trade-offs result in sound signals not always having the optimal acoustic characteristics.

“Some of the behaviours and adaptations described here delighted me, serving as powerful reminders that we underestimate animals, and that evolution comes up with ingenious solutions to the challenges animals face.”

There are many, many other topics and experiments that Mathevon discusses here, such as acoustic communication in birds (primarily to attract mates and defend territories), crocodiles (the social life of reptiles is underappreciated and includes acoustic communication), and underwater (including vocal dialects in various cetaceans). He discusses how vocalisations are produced and heard, how individuals learn to vocalize, how vocalizations express emotions, and how some species communicate by infrasound, ultrasound, or ground-borne vibrations. He explores how vocalisations are uttered between parents and offspring, in competition for partners, and in the real-world setting of complex social networks, rather than the sender-receiver dyads that are easier to study and interpret. Finally, he explains his arguments for saying that animals have a language, many languages in fact, even if none seem to reach the sophistication of human language.

This brings me to some criticism. First is the book’s somewhat haphazard structure. The discipline of ethology has been shaped by Tinbergen’s four “why” questions that deal with mechanism, adaptation, ontogeny, and phylogeny. In other words, how is a behaviour executed, what is its adaptive value, how does it develop during an organism’s lifetime, and how has it evolved over the generations? Mathevon dutifully introduces this legacy and for a moment I thought he would use it to structure the book. Though he refers to them where appropriate, the only line through these chapters that I could discover is Mathevon’s direct or indirect involvement in almost all the research discussed here (which, let me be clear, is a staggering achievement). Similarly, each chapter typically discusses four to six ideas and studies in a solid block of text, so could have done with breaking up using subheadings or even just decorative section breaks. My second point is that the book would have benefited from some diagrams. He now resorts to wordy descriptions of spectrograms of bird calls or of anatomical features (e.g. the proposed closed-circuit system that allows cetaceans to vocalise underwater without coming up for air). Quick point of clarification: the included illustrations by Mathevon’s father Bernard Mathevon are all animal portraits.

These are admittedly minor points that did not take away from me enjoying this book tremendously. The Voices of Nature is an immersive sonic journey, led by a tour guide with extensive knowledge of the subject. Some of the behaviours and adaptations described here delighted me, serving as powerful reminders that we underestimate animals, and that evolution comes up with ingenious solutions to the challenges animals face. Mathevon’s involvement with much of the research discussed here means he livens up the narrative with personal highs and lows, as well as the rare reveals of the practicalities of investigating animal behaviour. The level of technical detail is just right, he knows when to pull back and ends many chapters by highlighting how there is much more he could discuss. On that note, join me as I next turn to Why Animals Talk to see what Kershenbaum adds to the topic.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

The Voices of Nature

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The nature of consciousness is one of the hardest problems in biology. What exactly is it? Where did it come from? And are non-human animals conscious? Philosophers and scientists range from ascribing consciousness to all life (biopsychism), or even all matter (panpsychism), to attributing it exclusively to humans. Seemingly beyond the purview of empirical science due to its subjective nature, there is a lack of “intuitively attractive solutions” (p. xiii). In the opinion of Walter Veit, an assistant professor in philosophy, that just will not do. In this slim but advanced-level book, he outlines a mightily interesting thesis of how consciousness could have gradually evolved, which aspect of it likely appeared first, and why we urgently need to step away from taking human consciousness as our yardstick.

A Philosophy for the Science of Animal Consciousness, written by Walter Veit, published by Routledge in June 2023 (paperback, 144 pages)

Before we delve in, I note that several parts of this book have been previously published as articles and are here extended and improved upon. Given the above-mentioned wild sweep of alternative views, it might help to start by situating Veit’s ideas amidst his peers. I am doing this with the caveat that my background is in evolutionary biology, not philosophy, so bear with me while I try not to make a hash of this.
– First, Veit is a materialist: consciousness is a neurological phenomenon explainable in terms of biological matter. I have to stop myself from writing that the brain produces consciousness; “in a biological materialist picture of consciousness, subjective experience is constituted by particular mechanisms and processes of the nervous system. It is not “produced” by it” (p. 38). I think Ed Yong said the same in about an animal’s sensory world: “it is not separate from the body, but of it” (p. 333 therein). In case you are familiar with the movers and shakers in psychology and philosophy of biology, Veit’s style of philosophy fits alongside e.g. Kim Sterelny & Paul Griffiths, Peter Godfrey-Smith, and Daniel Dennett. It clashes with e.g. Thomas Nagel (of that famous 1974 paper) and David Chalmers who see an explanatory gap between mind and matter and call it the hard problem of consciousness.
– Second, Veit is a gradualist: consciousness did not appear suddenly but evolved gradually. As with other biological phenomena, we should expect “gradation and variation of it across the tree of life” (p. 24). This situates him close to (again) Godfrey-Smith, Frans de Waal, Michael Tye, and Todd E. Feinberg. Veit specifically wants to heed the late Donald R. Griffin‘s call for a cognitive ethology: “to study consciousness […] as an adaptive and evolved phenomenon in nature” (p. 15).

So, having characterised Veit’s ideas and his mission in this book (to give an evolutionary account of the origins of consciousness), how does he go about this? For consciousness to evolve by natural selection, it had to be a trait worth having. In other words, we need to answer “the functionalist question of what consciousness […] does for healthy sentient agents” (p. xiii). Veit’s answer to that? “The function of consciousness is to enable the agent to respond to pathological complexity” (p. 2). I admit that I struggled with the term “pathological complexity” as I find neither the term nor the link he makes between health and consciousness intuitive. Veit immediately admits this. Equally adequate and less confusing would be the term “life history complexity”. That is a term I can work with. Life history theory studies how organisms deal with the trade-off between growth and reproduction. Given a limited energy budget, you cannot maximize both. However, there are many different solutions to staying in the game of life by achieving reproductive success, which explains the mind-boggling diversity of life history strategies we observe around us.

“For consciousness to evolve by natural selection, it had to be a trait worth having. In other words, we need to answer the question of what it does for healthy sentient agents”

Having answered the question of what consciousness is for (to deal with life history complexity), you may well ask: when did life history become so complex? Veit argues that this happened during the Cambrian explosion, that slow-motion diversification of animal body plans that started some 539 million years ago. This resulted in a computational explosion in life history choices, creating strong selective pressures for the evolution of consciousness. But what of the preceding Ediacaran? Modern thinking increasingly questions how much of an explosion the Cambrian really represented and whether complex multicellular animals evolved earlier. Veit concedes to this but argues that for a long time, we see no signs of adaptations to predator-prey interactions. Until the Cambrian, that is. In my opinion, this is not that important a detail. Where exactly in time we situate Veit’s computational explosion does not change the logic of the argument. Note that, as opposed to some others, he veers away from positioning it much earlier in time and granting consciousness to single-celled organisms.

Okay, we have a “why” and we have a “when”, but we have so far skirted the “what”. What is consciousness exactly? Though Veit does not attempt the impossible by trying to define it, he does emphasize throughout that the human subjective experience cannot be our yardstick. For too long, research on animal consciousness has been held back by a top-down approach that asks how human-like other minds are. Instead, he advocates a bottom-up approach. Frans de Waal has elsewhere compared consciousness to an onion, consisting of layers. Veit here runs with that metaphor and takes a “reverse-engineering approach [that asks] for the most minimal form of consciousness” (p. 42). For this, he elaborates on the 2020 paper Dimensions of Animal Consciousness by Birch et al. who propose five aspects. Though we could argue endlessly about the exact number and kinds of dimensions, Veit thinks that there is nothing to be gained by trying to pin this down now. This is just a starting point for much-needed empirical work and can be refined later.

A large chunk of the book explains these five aspects and starts peeling back the layers, discarding them in sequence until there is only one left. The one-sentence summary of this is that he considers diachronic experience, synchronic experience, self-consciousness, and sensory experience to be later add-ons to a core built on evaluative experience. Let me say that again, but slower.
– Diachronic experience is the integration of experience across time (in humans this includes mental time travel) and is most easily put aside as a higher-order feature not present at the start.
– Synchronic experience describes how we experience a single self that receives all sensory input. However, several animal groups have brains that are more lateralized, resembling human split-brain patients. Their experience is likely more disunified without it being dysfunctional.
– Self-consciousness is the awareness of oneself as distinct from other beings and the outside world. Though it is easy to see how it evolved as organisms became more active agents, Veit does not think it lies at the origin, and it is hard to see how the remaining two arose out of a sense of selfhood.
– Sensory experience, the conscious awareness of what we perceive with our senses, is the other popular dimension of choice for many neuroscientists and philosophers as the root of consciousness. Veit contends that it, too, cannot explain how the other two arose out of it. Also, much sensory perception happens unconsciously.
– Given this stalemate, Veits suggests we consider evaluative experience. Some authors speak of emotions and moods, though Veit prefers the term hedonic valence, or simply put, whether something feels good or bad. This requires neither self-consciousness nor sensory experience.

“consciousness [has been compared] to an onion, consisting of layers. Veit here runs with that metaphor and […] starts peeling back the layers, discarding them in sequence until there is only one left.”

The payoff, especially for a biologist such as myself, comes in the chapter where Veit reverses his reverse engineering, as it were. He returns to the discarded dimensions to see if there are animal groups that possess only some of them and looks at gastropods, insects, cephalopods, fishes, reptiles, and corvids. This shows how, starting with just evaluative experience, sensory experience could quickly have evolved as an enrichment of evaluation. Selfhood could in turn have evolved as an enrichment of sensory experience. An evolutionary perspective can answer other puzzling observations. Take, for instance, the striking difference between the life histories of insect larvae and adults. The former focus on survival and are sensitive to pain, the latter focus on reproduction and seem unbothered by loss of limbs and other gruesome injuries, even if there is evidence that they respond to harmful stimuli with aversive responses and longer-term negative mood swings. An evolutionary perspective is also compatible with the loss of certain aspects of consciousness with time. What ultimately counts for an organism is the adaptive value; there is no march of progress here towards human-style consciousness.

The above is but a quick-and-dirty summary. Out of necessity, I have skimmed over many subtleties, objections, and responses to these. Hopefully, however, it gives you an idea of whether this is a book worth pursuing. A word of advice: do not let its 122 pages fool you, this is a slim but dense volume. In my earlier reviews of Godfrey-Smith’s books, I described Metazoa as a step up from Other Minds. Given the agreement between Veit’s and Godfrey-Smith’s views, how appropriate to suggest that this book in turn is a step up from Metazoa. It is squarely aimed at advanced-level students in philosophy, psychology, and cognitive sciences. If terms such as phenomenology or valence are not part of your daily vocabulary, you might find this work challenging. Despite the jargon, it is written with flair. It is also very clearly structured. Each chapter, and the book as a whole, outline what will be discussed, discuss it, and then summarise what has just been discussed. Furthermore, I appreciate that Veit remains humble and tones down the ambition of this project. This book is not intended to rule out other theories on the origins of consciousness. Rather, it seeks “to undermine an almost certain confidence seen in parts of the field” (p. 52) either that we have it all figured out, or that we can proceed no further figuring it out. A fresh take on consciousness, Veit offers an actionable way forward to cracking this nut and has written a challenging, thought-provoking, and worthwhile book.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

A Philosophy for the Science of Animal Consciousness

Other recommended books mentioned in this review:

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