Ever since humans appeared on the scene, we have been altering life on Earth. Where once our actions could be considered part of nature’s fabric, our influence has become outsized and our options to exercise it have multiplied. Though the subtitle of Life Changing does not make it explicit, science writer Helen Pilcher focuses on our impact on the genetics and evolution of life around us. A book that stands out for its balanced tone, it managed to surprise me more than once, despite my familiarity with the topics considered.

Life Changing: How Humans Are Altering Life on Earth, written by Helen Pilcher, published by Bloomsbury Publishing in February 2020 (hardback, 391 pages)

Life Changing is told in three acts. Pilcher first examines the species we have purposefully engineered, then looks at the many animals unwittingly caught up in the advancing human juggernaut, and finally considers how we might wield our knowledge for good in conservation efforts. Examining the work of numerous scientists, she takes the reader through topics as diverse as domestication, cloning, invasive species, urban evolution, de-extinction, and rewilding. Two aspects of her writing stood out for me in particular: she gets the nuances of these technical topics right, and she is balanced, not letting personal prejudice get in the way.

First, those nuances. As a former reporter for Nature and with a PhD in cell biology, Pilcher understands the biology and knows how to communicate it. Right off the bat, she clarifies that domestication is simply another form of genetic modification. Making a distinction between this and modern, laboratory-based methods, as GMO opponents are often wont to do, is a good example of the appeal to nature fallacy. The difference is one of degree, not of kind. She similarly puts the record straight on cloning: clones are not 100% genetically identical. Although you duplicate the nuclear DNA, you will need an egg cell in which to do so. The egg donor contributes its own mitochondrial DNA, which is a small but not insignificant fraction. With time, further differences accrue due to mutations and epigenetics (processes that change the way DNA is expressed without changing the DNA sequence). “We are all far more than the sum total of our DNA” (p. 136), remarks Pilcher. The last example is de-extinction, the subject of one of her previous books. Often misrepresented as resurrecting an extinct species, in reality it means genetically modifying a closely related species to resemble its ancestor. The result is “a hybrid modern-day facsimile” that “doesn’t mark a return to bygone eras; instead it marks an entirely new phase in the evolutionary story” (p. 138).

The second strong suite of Life Changing is Pilcher’s balanced reporting. Cloning has found many uses in animal breeding, but we must not forget that it is a notoriously inefficient process with most clones dying before birth—which is one reason why she would not want to clone her dog. When discussing the genetic changes wrought by trophy hunting, she admits finding the whole business repugnant but recognises how South Africa has shown that the money ploughed back into wildlife reserves benefits wildlife overall. “Although it may seem counter-intuitive, sometimes, hunting can actually help wildlife” (p. 63). And while invasive species have a bad reputation, she also speaks at some length to ecologist Chris D. Thomas. In his book Inheritors of the Earth, he pointed out how many invasive species simply slot right into an ecosystem without disturbing the locals. New Zealand now has nearly double the number of plant species. “Despite what you might have heard, invasive species aren’t all bad” (p. 229).

“[…] de-extinction [is] often misrepresented as resurrecting an extinct species, in reality it means genetically modifying a closely related species to resemble its ancestor.”

Particularly interesting is the topic of hybridisation. There is much concern about closely related species hybridising as climate change causes home ranges to shift, with pizzlies (polar–grizzly bear hybrids) being one example. But, just as humans contain some Neanderthal DNA, studies have shown grizzly bears to contain some polar bear DNA; one example of the book surprising me with something I did not know yet. It is estimated that the two species have occasionally interbred for the last 40,000 years. So should we panic? This is perhaps where Pilcher’s logic lapses slightly. When she introduces extinction and climate change she admits that, yes, these are natural processes that have always happened, but it is the current high rate that is worrisome. That same logic is not applied to her discussion of hybridisation. On the flip side, it can also be a conservation tool. The northern white rhino is functionally extinct as only two females remain. Using frozen sperm from the last, now deceased male, researchers inseminated a female southern white rhino, creating two hybrid embryos. Are we diluting the northern white rhino genome or preserving a significant fraction of it? “In some instances, maybe it’s better to have a hybrid than it is to have nothing at all” (p. 216).

Besides nuance and balance, Life Changing has several other things going for it. As a comedy writer, Pilcher has a wicked sense of humour. Regarding artificial insemination in cattle breeding, she declares: “Romance is dead, replaced by a glorified bovine turkey baster” (p. 53). Her description of zoologist Mark Carwardine’s encounter with an amorous kakapo simply has to be read; I will just leave you with the words “demented pair of sex-mad avian earmuffs” (p. 290). Sometimes, the humour is acerbic. Industrial animal farming is a major driver of the global decline in biodiversity. If somebody were to populate a new ark to reflect this shift in abundance, she half-jokes, the roll call would go “chicken, chicken, chicken, chicken, chicken, chicken, cow” (p. 353).

Pilcher knows when not to provide too much information. Whole books have been written about e.g. the long-running fox domestication experiment in Siberia, evolution in urban settings and the textbook example of the peppered moth evolving in response to changes in air pollution, the gene-editing tool CRISPR, or the stratigraphical definition of the Anthropocene and what marker will be suitable (it might just be chicken bones). For all of these topics, she manages to provide the relevant details in just a few pages.

“[…] just as humans contain some Neanderthal DNA, studies have shown grizzly bears to contain some polar bear DNA […] It is estimated that the two species have occasionally interbred for the last 40,000 years.”

In other cases, she goes into great detail. This book could be a rather depressing read, so in the last part, she explores in-depth some examples of how our knowledge and technical skills can stem the tide of biodiversity loss. Some researchers have figured out how to make coral spawn on-demand in the lab, allowing the reintroduction of live coral to sites affected by bleaching. There is the intensively managed Kakapo Recovery Program in New Zealand, and the hands-off approach of rewilding, such as the Knepp Estate in the UK. The topic of rewilding is where I find Pilcher at her least critical and most starry-eyed. Although there are places where she hints at human population numbers multiplying our impact, she never mentions overpopulation out loud. And beyond some hints at eating less meat, she does not really address what limits we ought to impose on ourselves if we want large-scale rewilding efforts to exist side-by-side with 8 billion people. Admittedly these are huge and divisive topics without easy answers that are outside of the scope of this book, but they are barely acknowledged here.

In her introduction, Pilcher pithily states: “Life is changing. Humans are responsible“. Life Changing is a very enjoyable piece of popular science writing that shows the many ways in which this is true. I was particularly pleased that, despite my familiarity with the topic, she still had surprises in store for me.

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

Life Changing

Other recommended books mentioned in this review:

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“She Has Her Mother’s Laugh: The Powers, Perversions, and Potential of Heredity“, written by Carl Zimmer, published in Europe by Picador in August 2018 (hardback, 656 pages)

With the narrative itself sprawling over more than 570 pages, the scope of this book is vast. In the hands of a lesser writer, the prospect of reading such a large book on a technical topic such as heredity might seem daunting. Zimmer, however, is very adept at combining his personal experience as a father with the results from historical and current scientific research, frequently highlighting the many human stories and dramas leading to new findings.

Starting with our understanding of heredity before Darwin, Zimmer walks us through Darwin’s failed attempt at explaining heredity in The Variation of Animals and Plants under Domestication (see also Van Grouw’s recent celebration of that book in Unnatural Selection), the forgotten work of Mendel that was rediscovered decades later, and the “laughably baroque” cell division process of meiosis that results in egg and sperm cells. There is the obsession of many people with genealogy, something that received renewed interest with the falling costs of sequencing technology. Zimmer has his own DNA sequenced and uses this as a hook to talk about ancient DNA recovered from archaeological remains and how this has revealed that we are all complex mosaics of many different ethnic groups, with even some Neanderthal DNA thrown in for good measure! (see also Pääbo’s Neanderthal Man: In Search of Lost Genomes and my review of Reich’s excellent Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past that goes into much more detail).

“If Charles Darwin were to walk into my office today and ask me: “So, what did I miss?” I think I would sit the good man down with a copy of She Has Her Mother’s Laugh“

Mendel’s principle of inheritance is not the only mechanism though. Zimmer goes into the discovery of the complex inheritance of traits such as height and intelligence that rely on small contributions from many genes, the nature/nurture debate and what studies on human twins have revealed, or the astounding discoveries that our bodies are mosaics of genetic variation due to localised mutation, and that some people are even chimaeras containing genetic material from more than two people.

The concept of heredity becomes even fuzzier once we start adding the discovery of the microbiome (the community of microbes that lives in and on us, see these three books for more), epigenetics (heritable changes due to changes in gene activity rather than sequence, see these three books for more), or the notion that culture is a form of heritability to pass on knowledge (see these three books for more). You can see why Bonduriansky & Day are calling for a reappraisal of the concept of heredity in their recent book Extended Heredity: A New Understanding of Inheritance and Evolution.

But what of this misappropriation? Ah yes, the dark side. Throughout all these various chapters Zimmer weaves the troubled contribution mental institutes have made to our understanding of heredity (see Porter’s book Genetics in the Madhouse: The Unknown History of Human Heredity), the subsequent rise of the eugenics movement that hoped to improve the human race through forced sterilization, the horrors of Nazi Germany, and the persistence of the outdated idea of race that for centuries has been used to justify slavery and racism (see strident takedowns in The Myth of Race: The Troubling Persistence of an Unscientific Idea and Superior: The Return of Race Science). Given his own Jewish background, his treatment of these topics is surprisingly dispassionate. Although he obviously opposes all of the above, his assertion that “it’s also a mistake to use Hitler as a label for all of eugenics” (p. 499) and his willingness to discuss Hermann Muller’s ideas on more progressive forms of eugenics shows Zimmer to be open-minded, or at least able to keep his writer’s cool.

“our bodies are mosaics of genetic variation due to localised mutation, and some people are even chimeras containing genetic material from more than two people”

This, of course, brings us to all the ethical quandaries stirred up by the discovery and application of CRISPR (see also my reviews of A Crack in Creation: The New Power to Control Evolution and Modern Prometheus: Editing the Human Genome with CRISPR-Cas9). This new tool to edit genetic material has the ability to cure diseases but could also be used for more questionable ends such as designer babies. There are no simple answers here, and Zimmer gives a great overview of the debates and the rapid pace with which this technique is developing.

As you can see, I have been reading into quite a few of the topics that Zimmer deals with. Even so, the quality of his narrative, the well-placed humorous comparisons, and the human portraits he mixes in make these chapters a joy to read. There were plenty of subjects that were new to me and especially the chapters on human mosaics and chimaeras at times made my eyes widen in astonishment. I envy the reader for who all this material is new – you are going to have a lot of fun reading this book. In that sense She Has Her Mother’s Laugh acts like a portal, introducing you to a huge number of topics relevant to heredity from which you can branch out to read more into areas of interest. The press has heaped praise on this book, calling it magisterial and sweeping. Having devoured the book from cover to cover in a day and a half, I can assure you this is no hyperbole. Zimmer has written an epic book that provides a vast panorama on our current and past understanding of human heredity and genetics.

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

She Has Her Mother’s Laugh paperback, hardback, ebook or audiobook

Other recommended books mentioned in this review:

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Some recent popular science books on the microbiome:

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Some recent popular science books on epigenetics:

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Some recent popular science books on culture as heredity: