Richard Dawkin’s “The Ancestor’s Tale”

This great 600 page book makes biology fascinating. I disliked biology in high school but this book thoroughly kept my attention. The emphasis is on the means of evolution but the book plan provides a systematic view of the entire gamut of life, centered on us humans and our successively larger sets of relatives. There are about 40 nested sets of critters and just the oldest few are not in sufficient focus to be sure of the family tree. Genetics gives promise of sorting this out soon.

Dawkins defines life as replication but with inheritance. Fire replicates but the behavior of the fire depends only on its current situation, not on the prior fire. Fire does not inherit characteristics from earlier fire.

Dawkins argues well that inheritance must come first or concurrently with metabolism. He is fond of the idea that RNA was the primordial replicator. He explains tRNA so that I understood how it works for the first time. He makes it plausible that some form of RNA can autocatalyze itself. He suggests that we are unlikely to find evidence of the original inheritor but are likely to find a highly plausible story thereof.

Dawkins likes Thomas Gold’s deep hot biosphere ideas.

I am charmed by the vaguely scatological morphology that differentiates bilateral animals. In both cases the blastula starts as a ball, then a cup, then a doubled walled ball with a hole. If the animal embryo is a Protostome then this hole is destined to become the mouth. ‘Protostome’ means “mouth first”. If the animal is a Deuterostome then this hole is destined to become the anus. ‘Deuterostome’ means “mouth second”. We are deuterostomes and spiders and insects are protostomes. It is easy to see that this was an early design freeze. Ether works but you don’t change thereafter. You don’t mess with the plumbing once you figure out how to do it. Common ancestors of us and insects had scarcely anything like an intestinal tract. Some such animals survive today—they are shaped like the double walled blastula. The protostomes crawl upside down! As they crawl, their “backbone” side is closer to the floor. Of course they have no back bone for they are exo-skeletal. Our anatomy differs enough form the protostomes to make this a hard call.

The inconvenient bdelloids (protostome) seem to have forgone sex for 40,000,000 years. They challenge nearly every theory about why animals and many plants need sex to survive long as a species. Recent genetics confirms no sex, at least of the sort that mix the two copies of the diploid chromosome. I think they have invented some sort of sex that mixes left with left and right with right. I can’t imagine how, however.

Like all of Dawkins books this one is full of weird animals and plants. There are not many pictures but with the names of these animals, Google gives a flood of pictures and further comments.

Overall the book is organized to give a superb top level view of life here on Earth. I now remember several dates that I had no grasp on before.