Photograph by Vivian Dullien.

Photograph by Al Denelsbeck.

Photography Contest, Honorable Mention.

I am going to step out of my lane again and tout this video, Something Weird Happens When You Simulate Lifeless Molecules, by Veritasium. What happens is that you get (simulated) life, natural selection, and so on. Professional biologists will no doubt find something to carp about. I did not especially like the term, "survival of the fittest," when I think he really meant "natural selection." My first impression was that he may have been conflating origin of life with evolution, though they are certainly closely related. He kind of pushes the selfish gene theory, but also states some criticisms and states flatly that genetic drift can sometimes overcome natural selection. He notes that his model is an oversimplification, but then, as he says, all scientific models are oversimplifications. I will let a real biologist discuss whether evolution takes place at the level of the gene, the individual, or indeed the group. As for me, I thought it was a splendid video which in a half-hour or so gave a clear understanding of how life can develop from non-life and go on to evolve into, well, endless forms most beautiful and most wonderful, several of which make cameo appearances in the video.

We got news of Mitch Cruzan’s new book on human origins and invited him to write a short introduction, which you may see here. In the meantime, the publisher graciously sent a review copy, and I report on the book below.

Mitch Cruzan is Professor of Biology at Portland State University and has by his reckoning been teaching evolutionary biology for 15 years. I recently read an advance copy of his new book, Looking down the Tree – The Evolutionary Biology of Human Origins. Although I suppose I am a fellow traveler, I am not a biologist, and occasionally something went over my head. I wondered, therefore, who the book’s intended audience was. Not unlike a paleontologist, I searched within the book and immediately found on page 15, "You probably know about DNA from your biology courses." I frankly thought that he should have aimed higher: it would not have taken much additional explanation to prepare a more popular book and not what I think amounts to a supplementary college text. Indeed, I thought that it would have been useful to have defined terms such as apocrine gland, homologous, and recombination for readers who have never had a biology course.

Cruzan argues convincingly that to understand our phenotypes, you have to look at our past, not our present. He thus begins each chapter with an anecdote from the daily life of a fictitious hominid he names Launua. Launua belongs to a clan that is barely surviving, having comparatively recently ventured into the savanna. Her clan is inbred (presumably not so much that it is deleterious) and held together by kin selection, or inclusive fitness. Cruzan sometimes seems to conflate inbreeding with kin selection and remarks that inbred populations display kin selection. Each chapter ends with a useful summary.

Cruzan asks, for example, why we have opposable thumbs. Not, as I understand it, because we need them for grasping, but initially because our upright posture necessitated an elongation of our big toes (not all our toes), and our hands followed along because they use the same regulatory genes. Here he uses the large thumb to introduce the concept of an exaptation, though later he uses the obsolete but more descriptive term preadaptation. Cruzan thinks,

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Mitch Cruzan is Professor of Biology at Portland State University. He received his BA and MA in Biology from California State University, Fullerton, and his PhD from Stony Brook University. He is currently an associate editor for Molecular Ecology, a leading journal in the field. He has published more than 80 papers in the primary literature and an advanced textbook, Evolutionary Biology: A Plant Perspective. His latest book, Looking Down the Tree – Exploring the Origins of Our Species, is due to be published in a few days, and we have invited him to offer a preview here.

I have offered an introductory course on evolution annually over the last 15 years. I always saved in-depth discussions of human evolution to the end for two reasons. First, to discuss human evolution in a meaningful way, we need to have a good understanding of evolutionary principles and processes. Second, I thought it was a good highlight for the course to end on. Each year, I incorporated new information and new ideas about human origins. Much of this content came from the questions that students asked; they weren’t satisfied to look a series of fossil remains or boring details about human genomics. They wanted to know more about the origins of our unique appearance and behaviors, and particularly secondary sexual characteristics.

Why does anyone take on a particular subject for a non-fiction book? You might ask, what could a plant evolutionary biologist such as myself possibly have to say about human evolution? Some reviewers actually said that I had no business writing this book. But evolutionary biology consists of a set of principles and processes that can be applied to any organism. Yes, it helps to have knowledge of the biology of a species, but for humans, that information is readily available. For me, developing the material was a natural process as I explored aspects of human evolution, along with the students in my introductory evolution lectures. By the time the pandemic hit, I had developed what I thought was a unique story of the origin of human traits – one that made sense in the context of the habitats our ancestors inhabited.

This book is not just a rehash of previous statements and ideas. By integrating information from disparate fields such as paleontology, anthropology, and genomics, I have drawn unique conclusions about the origins of human traits and behaviors.

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