Life Changing How Humans Are Altering Life on Earth

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 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. 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 "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. 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.

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). 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, the gene-editing tool CRISPR, or the stratigraphical definition of the Anthropocene. For all of these topics, she manages to provide the relevant details in just a few pages.

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.