As I stated in my previous post, I recently had a chance to read a review copy of an upcoming science book. It is due for release this Friday, and you can order a copy now from several book sellers. I highly recommend getting a copy and reading it, if you have an interest in paleontology, evolution, or the history of science. Written in Stone: Evolution, the Fossil Record, and Our Place in Nature, by Brian Switek, has all those things and more.
The book begins with a recent news story – recent paleontology news, that is. A fossil was described that “could be” the elusive, and conclusive, missing link in the human family ancestral chain. In fact, the find, and the fossil, were rather shamelessly promoted, hyped, and hinted about, all the while being kept from the eyes of the scientific community – all but the team of scientists who had prepared and described the fossil, at any rate. “Ida,” as the fossil was informally named, was a beautifully preserved specimen of a small, female, primate some 47 million years old. As this story unfolds, it illustrates several themes that weave through the rest of the book. One is that scientists are all looking for answers to big questions. It’s why they are scientists. They are driven to search for the truth, even if and when it goes against their previous assumptions about how the world works. But scientists are also human. The tendency to interpret findings to fit those previous assumptions is sometimes too much of a temptation to overcome, whether they are conscious of doing it or not. And there have always been scientists who make no pretense about using the data to support any view of life other than one about which they have already made up their minds.
In the case of this book, the answers are truly some of the biggest in the natural sciences: Where did we come from? Who are our ancestors and what did they look like? What can fossils tell us about the ancestors of other creatures with whom we share the present-day earth? And the real nail-biter in my mind – are birds really dinosaurs? There is also the question of whether or not the progression of life-forms through the fossil record shows a progression in another sense, that of evolution from “lower” forms, like simple invertebrates, to “higher” forms, like us. And although evidence reveals that even “simple” invertebrates are quite highly evolved and adapted for their role in nature, there will always be those who want a way to justify placing the human race at the top of some pinnacle of evolutionary achievement.
Switek tells the human stories along with the scientific throughout the book. He digs into the history of the science and finds the personalities that go along with the names. Most students of evolutionary biology are familiar with Charles Darwin, and know something about his life. But Thomas Henry Huxley, Richard Owen, Othaniel C. Marsh, Georges Cuvier, and others are just names, or, at best, shadowy figures at the edge of the stage. Switek has given them substance. He details the conflicts some had with each other, as well as some of the outstanding collaborations.
Each chapter is a separate case study in the history of evolutionary paleontology, using the keystone examples that most of us are familiar with from some course or other in biology. The story of the Archaeopteryx fossils and the debates over the evolution of birds from dinosaurs and whether birds started to fly from the ground up or the trees down is a good example. The feathered fossils, one of which was on exhibit recently at the Houston Museum of Natural Science, are billed as “icons of evolution.” That presence of feathers has now been confirmed on a number of dinosaur fossils has added weight to the placement of birds in a much closer relationship to dinosaurs than would have been considered when the Archaeopteryx fossils were first discovered.
Another “icon of evolution” for many of us has always been the story of evolution of the horse, from the tiny Eohippus – or “Dawn Horse” (now classified under an older name – Hyracotherium), to our present-day horses, zebras, and their relatives. Presentation of the evolution of horses as a steady march from one form to another – from the small, many-toed forms, to the large, modern ones with their single toes – has consistently misrepresented the true story of the ancestry of modern horses. Some of the forms that are shown in a line leading from smaller to larger, actually co-existed at some point in the past and are not closely related. A more accurate portrait of the horse family is of a bush, with many of the branches containing the smaller forms dying out along the way.
Also included in the book is the chapter describing the search for the true evolutionary path of whales, which have been shown through recent molecular studies to be more closely related to hippos than to groups previously proposed as their ancestors. This points out another theme important to Switek, that the field of paleontology has something to contribute to other disciplines in evolutionary science, as well as being able to be enriched by knowledge from those other disciplines.
For anyone with a keen amateur interest in paleontology, this book has everything one could hope for in a single basic reference. There is history, drama, and all the major players – the fossils themselves – telling the stories that are much larger, and much more interesting, than merely a tale of “missing links.”
