A review by davidr
Improbable Destinies: Fate, Chance, and the Future of Evolution by Jonathan B. Losos

5.0

I love books about science that are written by scientists in the field, especially when they can write well. This means that not only are their books informative--that is the bare minimum--but they also have a fun attitude, and they put the reader into the story of their investigations. Well, this book by Jonathan Losos does exactly that. While he gives the reader all the background story of what other scientists have done, he also conveys all the starts and stops and challenges that he faced while doing his own research. And, what a lot of challenges he faced! Losos writes some wonderful anecdotes about the dangers of being a scientist working in jungles. On Trinidad, he writes about snakes, booby traps, dangerous rocks, army ants, and even being attacked simultaneously by snakes and army ants!

The major theme of this book is the controversy about how predictable is evolution? To what extent is it convergent--meaning that regardless of the circumstances, species will tend to evolve along a certain, deterministic path--or divergent, meaning that slight changes in the environment will cause a species to evolve into some different, essentially unpredictable path. Much of the controversy began with the publication of [b:Wonderful Life: The Burgess Shale and the Nature of History|36475|Wonderful Life The Burgess Shale and the Nature of History|Stephen Jay Gould|https://i.gr-assets.com/images/S/compressed.photo.goodreads.com/books/1480836482l/36475._SY75_.jpg|55914] by Stephen Jay Gould. Gould argued that evolution does not necessarily proceed at a slow, gradual pace. Sudden environmental changes can evoke rapid sprints in evolution.

There are lots of examples of convergent evolution. Porcupines in Africa and Asia look similar, though they evolved independently from their common ancestor. Humans on different continents evolved their abilities to be lactose-tolerant evolved independently and differently on different continents, as well as their light-colored skins in northern latitudes. Many species of animals that evolve on islands all develop into miniature versions of their continental cousins. The smaller the island, the smaller the surface area-to-volume ratio becomes.

Losos writes of his own research on very small islands, where he studies the rapid evolution of lizards in response to sudden importations of predators. Significant evolution can take place in just a few years. Proving this, though, can be difficult when hurricanes can overnight wipe out the entire lizard population of an island!

Losos writes about some very interesting research with a benign form of E-coli. The bacteria were cleverly followed over tens of thousands of generations, to find that a rare sequence of mutations can lead to a totally new type of metabolism!

A major point in the book is that "Species that are initially different will not take the same evolutionary route in response to similar selective pressures." If the dinosaurs had survived, it's not obvious that their descendants today would be similar to us. It is more probable for evolution to have developed an intelligent being that looks like a super-sized brainy chicken. On the other hand, species frequently evolve similar features in response to similar environmental conditions. The main lesson from the book is that "Evolution is not random or haphazard."

This is an excellent book, engaging and informative. There is not a lot of jargon--you don't have to be a scientist to follow along. The study of evolutionary biology is now speeding along, because of the great advances in analyzing DNA. It's fun to go along for the ride!