The Ancestor's Tale: A Pilgrimage to the Dawn of Life is a popular science book by the evolutionary biologists Richard Dawkins and Yan Wong. It retraces the history of life in reverse chronological order: A growing band of species meet their most recent common ancestors (concestors) at 40 rendezvous points. First published in 2004, it was updated in 2016 to reflect recent discoveries. Many reviewers described it as Dawkins's magnum opus.
Background The book is patterned on Geoffrey Chaucer's The Canterbury Tales, in which pilgrims en route to Canterbury converge with other travelers and tell tales. Here, species convene with their common ancestors, and "Canterbury" is the origin of life. The epigraph is from Mark Twain: "History doesn't repeat itself, but it rhymes." The authors argue that "Evolution rhymes, patterns occur. And this doesn't just happen to be so. It is so for well-understood reasons: Darwinian reasons, mostly, for unlike human history or even physics, biology already has its grand unifying theory." They note that no living species is ancestral to any other, but that all share a common ancestor. Evidence for this fact is that the code for translating genes into proteins is universal. Since genes and proteins are more similar in closely related species, they act as molecular clocks that show us when species split. The authors use concestor, coined by Nicky Warren, to describe the most recent common ancestor at each rendezvous point. The pilgrimage proceeds through extant species, with the exception of early hominids like Homo habilis, and species like the dodo, whose DNA is available to us. The book was revised in 2016. Notably, "The Denisovan's Tale", about paleogenetics, replaces "The Neanderthal's Tale" and "The Sloth's Tale", about biogeography, replaces "The Armadillo's Tale". "The Galápagos Finch's Tale", about natural selection, includes new research on the genetics of Darwin's finches, and the conclusion of "The Elephant Bird's Tale" has been updated. The phylogenetic trees in the second edition are based on OneZoom evolutionary mapping software. In 2005, on a pilgrimage to the Galápagos, Dawkins wrote three new tales. The third is reprinted in the second edition.
Tales
All Humankind
Archaic Homo sapiens
Nonhuman Primates
Non-primate mammals
Non-mammal chordates
Non-chordate animals From the lancelets onward, the authors provide dates under duress stating that "dating becomes so difficult and controversial that my courage fails me".
Non-animal eukaryotes There are essential differences between the 1st and 2nd editions of the book in this section. Another rendezvous has been added (#33), and the unknown rendezvous has been partially resolved.
Great Historic Rendezvous The authors describe the origin of eukaryotes (Greek, "true kernel"), organisms with a cell nucleus and Lynn Margulis's endosymbiotic theory. Mitochondrion and chloroplasts have their own DNA and divide by binary fission, like bacteria. Margulis surmised that this is because they are descended from free-living bacteria.
Prokaryotes Prokaryotes (Greek, "before kernel") lack a cell nucleus. They can move genetic material between unicellular and multicellular organisms via horizontal gene transfer.
“Canterbury” The authors speculate about the origin of life, from Darwin's "warm little pond" through J. B. S. Haldane and Alexander Oparin’s “primordial soup”, the Miller–Urey experiment and Spiegelman's Monster. In 1952, Stanley Miller and Harold Urey mixed methane, ammonia, hydrogen and water and sparked it with electricity. The product included seven amino acids, among them glycine, aspartic acid and alanine, among the twenty used to make proteins. In 1965, Sol Spiegelman seeded test tubes with enterobacteria phage Qbeta, and found it was subject to variation and selection. RNA can catalyze chemical reactions (like an enzyme) and store information (like DNA), indicating that it may have been the first replicator. The discovery of life near hydrothermal vents indicates that life may have begun deep underwater, or underground.
“The Host’s Return” Dawkins, in the spirit of Stuart Kauffman, speculates on what would happen if evolution were “rerun”. Eyes have evolved as many as forty times convergently, as Dawkins describes in "The Forty-Fold Path to Enlightenment" in Climbing Mount Improbable. Several species have evolved gliding: colugos, flying squirrels and sugar gliders. From so simple a beginning, flight has evolved at least four times (in insects, pterosaurs, birds and bats). Echolocation has also evolved at least four times (in oilbirds, cave swiftlets, cetaceans and, again, bats) as Dawkins describes in "Making Tracks Through Animal Space" in The Blind Watchmaker. However, as seen in “The Rhizobium’s Tale”, wheels seem to have evolved only once, in bacteria. Similarly, syntactic language seems to have evolved only once, in humans. He concludes that science gives meaning to human existence: “Not only did evolution happen, it eventually led to beings capable of comprehending the process, and even of comprehending how they came to comprehend it.”
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