International Society for Science & Religion - Library Project

Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom

by Sean B. Carroll

Introductory Essay by MIchael Ruse

The first half of the nineteenth century saw much interest in embryological research.  Thanks particularly to the work of Karl Ernst von Baer, it was realized that very different adult organisms frequently have nearly indistinguishable embryos. In his Origin of Species, Darwin made much of this fact, explaining it as a result of evolution through natural selection. But so little notice was taken of this that, semi-humorously, Darwin grumbled that his friends had ignored the single most important piece of evidence for evolution.

In the years following, however, much was made of embryology, albeit generally in a very non-Darwinian (meaning non-selective) context, with the German evolutionist Ernst Haeckel making development the linchpin of his fundamental “biogenetic” law: “ontogeny recapitulates phylogeny.” Embryology was seen as having less to do with the causes of evolution and much to do with working out past histories. When in the 1930s natural selection was revived as a mechanism and blended with understanding from Mendelian (later molecular) genetics into the so-called “synthetic theory of evolution,” embryology was basically ignored. Evolutionists worked with genes and with full-blown organisms, and everything in between was an ignored black box.

How things have changed! Thanks particularly to increasingly detailed studies of the genetic makeups (genomes) of organisms, more and more attention has been given to embryology, or as it is now often called (stressing the context in which it is discovered) “evolutionary development” or “evo-devo” for short. Some of the most stunning findings have been of how the same genes, in the same orders, are shared by organisms as different as fruitflies (Drosophila) and humans. We are all built on the Lego principle – you take the genes and do one set of things and you get an insect; you take the same genes and do another set of things and your get a primate.

The biologist Sean B. Carroll is a leader in the field of evo-devo, having done some of the fundamental studies. He is also a brilliantly gifted writer, and Endless Forms Most Beautiful: The New Science of Evo Devo is a sparkling introduction to the whole subject.  He takes you through the history of life, showing how there were periodic explosions of life and forms that forever changed the course of evolution – the Cambrian explosion for instance, more than half a billion years ago. He shows also how we can now speculate profitably on causes, primarily by taking what was already there and moving and repeating and doing much more without necessarily inventing anew. He also introduces you to life today, showing the complexities involved in producing a fully functioning organism from the information coded in long strings of molecules.

Fascinating from a broader perspective is the significance of complexity and order. So often, it is not what you have, but how it is put together that matters. None of this threatens a naturalistic perspective on life – indeed, if ever proof was needed of the research sterility of Intelligent Design Theory (stopping all further discussion with an appeal to miracles), evo-devo provides it. But at the same time, simplistic reductionistic views of nature, of life specifically, are inadequate. To understand life and its history, and to understand the causes (the verdict is still not in on how significant a force is natural selection under the new regime) a holistic, more emergentist philosophy is needed. This is science at the cutting edge – new findings, new ideas, and above all, new implications for philosophy (and, no doubt, religion).