Weekly reading: The Ancestor’s Tale

27 Oct

WE– you and I– literally share a common ancestor with this unworldly creature!  And for that matter with all other life on planet Earth.

“The ravishingly beautiful Cestum veneris is one of those rare animals whose English and Latin names mean exactly the same thing, Venus’s girdle, and no wonder: the body is a long, shimmering, ethereally beautiful ribbon, too good for a goddess.” –Richard Dawkins  (Video from YouTube user quixoticknight used with permission.)

In The Ancestor’s Tale (Houghton Mifflin, 2004), Richard Dawkins guides the reader on a “pilgrimage” backward in time toward the common ancestor of all living things, which lived more than 3 billion years ago.

Tracing the evolutionary thread of humankind, the author describes 40 “rendezvous points” where humans come to share ancestors with distant cousins, from chimpanzees to eubacteria.

Along the way Dawkins treats us to captivating zoological tales that capture earth’s sublime diversity. (See, especially, the ayeaye, the platypus, Venus’s girdle, and the mushroom “phallus impudicus.”)

Why do peacocks have spectacular plumage? Why do we have big brains, two feet and forward-facing eyes? Why does the elephant have a trunk? The short answer is that all these things are handy, but Dawkins’ long answers are clear, satisfying and poetic.

For cherry-pickers interested specifically in genetics, see: “The General Prologue” on codons and DNA; “The Tasmanian’s Tale” and “Eve’s Tale” (Rendezvous 0), explaining gene survival and sex-linked inheritance; “The Gibbon’s Tale” (Rendezvous 4), on reading and comparing genomes; “The Mouse’s Tale” and “The Beaver’s Tale (Rendezvous 10), on phenotypes and genes shared across species; “The Peacock’s Tale” (Rendezvous 16) on sexual selection; “The Brine Shrimp’s Tale” (Rendezvous 26) on instinctive “knowledge,” “The Grasshopper’s Tale” (Rendezvous 296) on race, culture and genetic “bottlenecking”; “The Fruitfly’s Tale” and “The Rotifer’s Tale” (Rendezvous 26) on Hox genes and sexual reproduction; “Sponges” (Rendezvous 31) on cell types, and “Canterbury” on RNA, proteins and the origin of life.

For students of genetics, Dawkins presents an especially useful analogy in the “Mouse’s Tale,” likening genes to toolbox subroutines in computers. The routine that hides the cursor while the mouse is at rest is the same across the various programs that you use because they are “built in” to programmers’ repertoires, just as DNA routines are available in the genomic toolbox– across species– for performing standard biochemical functions.  That is why the human genome and the mouse genome are so alike in content and in size.

Dawkins explains and captures the wonder of our genetic interrelatedness on this planet.

(In many chapters Dawkins shares writing credit with research assistant Yan Wong.)


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