Thought Experiment

Exploring the evolutionary origins of our brains

Metazoa: Animal Life and the Birth of the Mind by Peter Godfrey-Smith; Farrar, Straus and Giroux, 352 pp., $28

I’ve written several books about the natural world and read countless others, but never have I encountered anything like Metazoa. In it, Peter Godfrey-Smith, a professor of history and philosophy of science at the University of Sydney, focuses on the evolutionary developments that shaped our brains, and no matter how much you think you know about these developments, his book will deepen your understanding.

Subjects such as the evolution of the mind are usually discussed by scientists in papers intended for other scientists. Are these papers interesting? Not really, because so many scientists don’t seem to care whether or not nonspecialists understand them. As science journalist Dalmeet Singh Chawla recently commented, “Science is becoming more difficult to understand due to the sheer number of acronyms, long sentences, and impenetrable jargon in academic writing.” How true.

Godfrey-Smith, however, favors clarity, presenting our world to scientists and nonscientists alike, salting his book with firsthand observations and experiences. Here’s a quotation, chosen at random, about his encounter with an octopus while scuba diving and his attempt to determine its sex:

[M]ales often move in a way that gives some protection to a particular one of their arms. This, in most species, is the third right arm. An octopus’s eight arms circle its mouth, but if you look at the animal from the front, the arms are arrayed in a way that presents two in the center—the first arms, left and right. Outside them are the left and right second arms, and so on, back to the fourth pair. The underside of the third right arm in males has a specialized duct used in mating, and males tend not to expose that arm as much as other arms. This octopus’s right third arm was moving all over the place with the rest, so I will treat her as a “she.”

Just as there’s no impenetrable jargon here or anywhere else in this marvelous book, neither does Godfrey-Smith call an animal “it” unless he has no choice. It has been the standard pronoun used by scientists for any species except ours. But whether they be little organisms in the oceans or bears who walk out of the woods, animals are not inanimate objects. We may not easily recognize their sex, but we know they have one.

Godfrey-Smith’s insistence on using the proper pronouns is in line with his mission to heighten our sensitivity  to the plight of all of nature’s creatures. We learn, for example, that clams and oysters feel pain and that the researchers who experiment on these mollusks are “calling for more care and oversight, the use of anesthetics, and a reduction in the number of animals used.” Such research, Godfrey-Smith writes, is crucial, because without learning about these creatures’ nervous systems, “people might well have continued mistreating them in large numbers with hardly a thought. Now, their felt experience is at least a topic of reflection, and some moves are afoot to change what we do.”

The stunning diversity of the animal kingdom is on full display in Metazoa, as are the processes by which that diversity of life came to be. First, bilateral fish evolved, then crept out of the water and began life on land. By then, their brains were evolving in many directions, with our evolutionary line, the synapsids, arising before being mostly erased during an extinction period. Then the dinosaurs ruled the planet for more than 165 million years until the next extinction, after which the synapsids rose again. Meanwhile, Godfrey-Smith tells us about plants, which not only support life by extracting oxygen from carbon dioxide but have their own form of cognition.

This book covers subjects taught in graduate-level biology courses but in a more compelling way. I am unaware of any other book on this subject that is as fluidly written or as accurate. But perhaps there will be another one soon! In discussing questions about brains, Godfrey-Smith writes, “I am not going to push much further with those questions here, saving many of them for another book that will consider, among other things, the factors that conjoin to make humans such unusual animals.”

I, for one, will be first in line to buy his next book.

Permission required for reprinting, reproducing, or other uses.

Elizabeth Marshall Thomas is the author of many books on animals and nature, including The Tribe of Tiger: Cats and Their Culture and The Hidden Life of Dogs. Her most recent book is Growing Old: Notes on Aging With Something Like Grace.


Please enter a valid email address
That address is already in use
The security code entered was incorrect
Thanks for signing up