The Ancestor's Tale
The Ancestor's Tale: A Pilgrimage to the Dawn of Life is a popular science book by Richard Dawkins and Yan Wong in which the history of life is retraced in reverse chronological order. A growing band of species meet their most recent common ancestors. First published in 2004, it was updated in 2016 to reflect recent discoveries. In 2005, during a pilgrimage to the Galápagos, Dawkins wrote three new tales. The third is reprinted in the second edition. The phylogenetic trees in the second edition are based on OneZoom.
The book is patterned on Geoffrey Chaucer's The [Canterbury Tales], in which pilgrims on the road to Canterbury converge with other groups of pilgrims. Here, species convene with concestors, and "Canterbury" is the origin of life.
Dawkins dedicated the book to John Maynard Smith: “He saw a draft and graciously accepted the dedication, which now, sadly, must become In Memoriam.”
Background
The epigraph is from Mark Twain: "History doesn't repeat itself, but it rhymes." The authors contend 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 emphasize that no living species is ancestral to any other, but that all share a common ancestor, some more recently than others. Evidence for this fact is that the genetic code for translating genes into proteins is universal. More closely related species have more similar genes and proteins. Genes and proteins act as molecular clocks that allow us to determine when species split. They use concestor, coined by Nicky Warren, to describe the most recent common ancestor at each rendezvous point.It is patterned on Geoffrey Chaucer's The Canterbury Tales, in which travelers take turns telling tales. The pilgrimage progresses through extant species, with a few exceptions: “Animals such as the dodo, which survived into historical times and whose DNA is still available to us, are treated as honorary members of the modern fauna starting off on our pilgrimage. … Since we are responsible for their recent extinction, it seems the least we can do. The other honorary pilgrims, exceptions to the rule that dead man tell no tales, really are men. Since we human pilgrims are directly seeking our own ancestors, fossils that might plausibly be considered candidates for being our ancestors are deemed members of our human pilgrimage and we shall hear tales from these shadow pilgrims, for example the Handyman, Homo habilis.” The pilgrims do not speak in the first person, as the authors think that "twee."
The book was revised in 2016 in light of recent discoveries. Notably, The Denisovan's Tale replaces The Neanderthal's Tale and The Elephant Bird's Tale has been updated. The Mudskipper's Tale was present in the first edition but not the second. The Armadillo's Tale, about biogeography, is now The Sloth's Tale.
Each Tale illustrates an aspect of evolution. The Galapagos Finch's Tale is about natural selection, The Peacock’s Tale about sexual selection, The Salamander’s Tale about speciation, The Barnacle’s Tale about how appearances can be deceiving.
Chapters
Archaic Homo sapiens
| Rendezvous point | Time | New Pilgrim | Story |
| 1 | 6 mya | Chimpanzees | The Chimpanzee's Tale is about the comparison of human and chimpanzee genomes. The authors note that human chromosome 2 formed from a recent fusion, which is why the other Great Apes have 24 pairs of chromosomes and humans have 23. The Bonobo's Tale is about incomplete lineage sorting. |
| 2 | 7 mya | Gorillas | The Gorilla's Tale considers human's changing attitude towards the great apes, ending with a discussion on racism, speciesism and the Great Ape Project. |
| 3 | 14 mya | Orangutans | The Orangutan's Tale is about parsimony. The authors introduce the principle of parsimony and its use in construction of cladograms. They discuss the possibility that the ancestors of the Great Apes were in Asia, where one line stayed and gave rise to Orangutans, where they are found today The other line went to Africa and gave rise to Gorillas, Chimpanzees and humans. They find this more parsimonious than the alternative. Orangutan is the last of the Great Apes to join the pilgrimage. |
| 4 | 18 mya | Gibbons | The Gibbon's Tale is about phylogenetics. The authors note that the genetic code is degenerate. As a result, “some DNA codes are synonymous: they specify exactly the same amino acid.” Synonymous substitutions are invisible to evolution but not to biologists. Since they are not subject to selection, they show greater variation between species. The same is true of pseudogenes. Coding regions are conserved sequences. Rare genomic changes are unlikely to have arisen independently, and are likely due to common descent. The authors note that “literary scholars use the same techniques as evolutionary biologists in tracing the ancestries of texts. And – almost too good to be true – one of the best examples happens to be the work of the Canterbury Tales Project.” Gibbon is the last ape to join the pilgrimage. |
| 5 | 25 mya | Old World monkeys | Old World monkeys, being in the same Catarrhini clade as apes, are closer cousins to apes than to New World monkeys. Old World monkeys are sometimes called the 'tailed apes'. It is not known if the actual common ancestor had a tail or not. |
| 6 | 40 mya | New World monkeys | The Howler Monkey’s Tale is about gene duplication and how it creates new genes. When a gene is copied, it can evolve a new function. This happened in the evolution of color vision in primates. Old World Primates are trichromats, with three opsins, each coded for by a specific gene. The red and green opsin genes are similar, and adjacent on the X chromosome. They are derived from a recent duplication. Mutations that improved the function of the new gene were selected for until the opsin could detect a different wavelength. Most New World monkeys are dichromats, with either red or green genes on the X chromosome. In some species, both red and green alleles are present in the population as a polymorphism. In Howler monkeys, both genes were put on the X chromosome through a translocation. As often happens in evolution, the same end was reached via different means. |
| 7 | 60 mya | Tarsiers | The Tarsier's Tale is about its enormous eyes. Unlike most nocturnal mammals, they lack a tapetum lucidum to reflect light from the back of the eye for a second exposure on the retina. The ancestor of the tarsier was a diurnal animal which lost the tapetum lucidum. In 2013, Archicebus, the oldest primate fossil found so far, was discovered in China. |
| 8 | 65 mya | Lemurs and Bushbabies | The Aye-Aye's Tale is about island ecology. In Madagascar, a small strepsirrhine founding population evolved to fill available niches. Today, it is home to as many as one hundred species of lemur. Lemurs, kin to lorises and pottos, are found only on this island. “Like virtually everything else that lives on Madagascar, it does not exist anywhere else on Earth.” Douglas Adams was writing of the aye-aye, but Madagascar is also home to six of the world’s eight species of baobabs. With a landmass 1/1000 of Earth's total land area, it accounts for 4% of all species of flora and fauna. |
File:Chicxulub impact - artist impression.jpg|thumb|center|upright|350px|The Cretaceous–Paleogene extinction event occurred 65 million years ago, due to an asteroid impact event which created the Chicxulub Crater, possibly aided by large scale volcanic activities in the Deccan Traps.
Non-mammal chordates
| Rendezvous point | Time | New Pilgrim | Story |
| 16 | 320 mya | Sauropsids | "Reptile" is not a true clade name. Dinosaurs, unfortunately extinct, are joined by their only surviving descendants, the birds. |
| 16 | 320 mya | Sauropsids | The Lava Lizard's Tale is about geology. Dawkins describes his pilgrimage to the Galápagos island of Santiago, visited by Darwin in 1835. A volcano erupted there one day in 1897. The events of that day are written in the island’s rocks, and we can read them. Dawkins describes the unique flora and fauna of the archipelago, and the camouflage used by the lava lizard. |
| 16 | 320 mya | Sauropsids | The Galapagos Finch’s Tale is about natural selection and how it can produce rapid evolutionary change. Peter and Rosemary Grant have found this through their long-term study of Darwin’s finches. In 1977, the island of Daphne Major was struck by drought, which created selective pressure for longer beaks capable of cracking the tough seeds of Tribulus: “The average beak length after the drought was 11.07 mm long compared with 10.68 mm before. The mean depth of beak had similarly gone up from 9.42 to 9.96.” In 1982-1983, there was a flood brought about by El Niño event|El Niño]. The selective pressure changed to favor smaller beaks that could eat the smaller seeds of Cacabus. The finches again evolved accordingly. In 2015, the Grants, along with researchers at Uppsala University, “located a number of DNA regions that co-varied with beak shape and homed in on a gene called ALX1… The ALX1 gene tree, deduced from Galapagos finch populations, shows branching patterns indicative of natural selection.” |
| 16 | 320 mya | Sauropsids | The Peacock's Tale is about sexual selection and how it can produce rapid evolutionary change. The peacock's plumage evolved because generations of peahens preferred plumage. R. A. Fisher found that genes making males have a trait are linked to genes for females preferring that same trait, leading to runaway evolution. Dawkins describes this in The Blind Watchmaker. |
| 16 | 320 mya | Sauropsids | The Dodo’s Tale is about island biogeography. Many birds colonizing oceanic islands convergently evolve flightlessness. Since these islands lack predators, wings aren’t selected for, and become vestigial. This happens even if wings would be useful in the future. This was sadly true in the case of the dodo, as wings would have proved useful when men arrived in Mauritius with clubs. On a happier note, biologists led by Alan Cooper have analyzed mitochondrial DNA from dodo specimens, and found they were related to pigeons. |
| 16 | 320 mya | Sauropsids | The Elephant Bird's Tale is about island gigantism. Many species colonizing oceanic islands evolve rapidly in size, as seen in the extinct elephant bird of Madagascar and the moa of New Zealand. In the first edition, Dawkins speculated that extant ratites evolved flightlessness convergently rather than inheriting it through a single flightless ancestor. Molecular evidence, from Cooper’s study of Elephant Bird DNA, confirms this. |
| 17 | 340 mya | Amphibians | Mammals and reptiles join the amphibians to meet the ancestor of all land vertebrates with four feet, the tetrapod. Amphibians include frogs, toads, salamanders, newts and caecilians. While amniotes either give live births or lay waterproof eggs, the amphibians retain the ancestral practise of laying eggs in water. Unlike the waterproof skin of amniotes, the amphibian skin allows body water to evaporate through it, restricting amphibians to land areas with access to fresh water. Almost no amphibians live in saltwater which explains why they are seldom found on islands. The concestor probably already had settled on five digits on each limb. |
| 17 | 340 mya | Amphibians | The Salamander's Tale is about speciation. When a species inhabits a geographic ring, “there is potentially gene flow around the ring. Potentially.” Robert C. Stebbins studied the Ensatina salamanders, which inhabit a ring surrounding California’s Central Valley. Around the ring, neighbouring populations of Ensatina can interbreed. But the plain Ensatina eschscholtzii on the western end cannot interbreed with the blotched Ensatina klauberi on the eastern end. Moving westward round the ring, populations become progressively plainer until they resemble Ensatina eschscholtzii. Moving eastward, populations become gradually more blotched until they resemble Ensatina klauberi. The authors write that ring species “are only showing us in the spatial dimension something that must always happen in the time dimension.” |
| 17 | 340 mya | Amphibians | The Narrowmouth's Tale is about parapatric speciation. Gastrophryne olivacea and Gastrophryne carolinensis are closely related. The most noticeable difference is in their mating calls. The former species has adapted to the western United States, the latter the eastern. But their ranges meet in the middle. It is there that their mating calls differ most sharply. Theodosius Dobzhansky theorized that this was due to reinforcement: natural selection favours adaptations that make interbreeding less likely. This causes character displacement, where two related species differ more in areas where they overlap. |
| 17 | 340 mya | Amphibians | The Axolotl's Tale is about metamorphosis, by which larvae change into dramatically different adult forms for reproduction. A frog has genes for making a tadpole. John Gurdon dramatically demonstrated this in 1962 by transplanting the nucleus of an adult frog into an enucleated cell, which developed into a tadpole. This work won him the Nobel Prize in Physiology or Medicine in 2012. Most salamanders undergo metamorphosis. They pass through a larval stage with “long, feathery external gills” which they lose as adults. Axolotls exhibit pedomorphosis, a process which enables juveniles to become sexually mature without developing into their usual adult forms. Axolotls remain aquatic and retain the gills. Julian Huxley found that with a treatment of thyroxine, it is possible to induce an axolotl to develop into a mature salamander. On the other hand, the newt first develops from tadpole into a land-based salamander, but later reverts to its juvenile form, returning to the water to reproduce. |
| 18 | 415 mya | Lungfish | Despite their morphological similarities, the lungfish and coelacanth are very different genetically, as expected of species which lived separately for more than 400 million years. One lungfish has the record for largest genome at 133 billion base pairs compared to our 3 billion base pairs. |
| 18 | 415 mya | Lungfish | The Lungfish's Tale is about the evolution of tetrapods. The authors trace transitional fossils documenting this transformation: Eusthenopteron, Panderichthys, Tiktaalik, Acanthostega and Ichthyostega. They speculate about selection pressures might that drove fish to land. For many years, the favored idea was that of Alfred Romer, that fish who could move from a drying pond to a deeper one had an advantage. Among the six extant species of lungfish, the South American lungfish and four species of African lungfish do something similar today, using their lungs to make it through dry seasons. But the Devonian does not seem to have been defined by drought, and Romer’s idea has fallen out of favor. But Steven Balbus notes that Earth’s moon was once much closer, and its tidal forces much stronger. It is possible that this concestor was moving from tide pool to tide pool.. The lungfish’s eponymous organ is likely homologous to ours, inherited from concestor 18. |
| 19 | 420 mya | Coelacanths | The Coelacanth's Tale is about so-called “living fossils”, of which the coelacanth is a celebrated example. The authors describe its discovery by Marjorie Courtenay-Latimer. However, even species that show little phenotypic change undergo molecular evolution, as revealed by genetic analysis. The reasons are seen later in the pilgrimage. |
| 20 | 430 mya | Ray-Finned Fish | The current pilgrimage consisting of all descendants of lobe-finned fish is joined by the equally successful ray-finned fishes which includes sturgeon, paddlefish, eel, herring, carp, salmon, trout, seahorse, cod, etc. to meet concestor 19, the bony fish. Of all ray-finned fishes, by far the most belong to the infraclass teleostei. |
| 20 | 430 mya | Ray-Finned Fish | The Leafy Sea Dragon's Tale is about the plasticity of animal forms. Evolution has molded many teleosts into strange shapes. The leafy sea dragon hangs motionless among kelp, which it resembles. Shrimpfish have been elongated to resemble strands of seaweed. The snipe eel has been stretched, while the gulper eel sports grotesquely large jaws. The ocean sunfish, weighing up to two tons, resembles a vast disc or millstone, as its Latin name, Mola mola, suggests. Teleosts can control buoyancy because of a unique adaptation, described in the next tale. |
| 20 | 430 mya | Ray-Finned Fish | The Pike's Tale is about the evolution of the swim bladder. Contrary to common belief, it is not the progenitor of the lung. The bony-fish ancestor possessed a primitive lung which, in teleosts, was co-opted as the swim bladder, used to maintain hydrostatic equilibrium. In some teleosts, it is used as resonating device. Such exaptation is common in evolution. |
| 20 | 430 mya | Ray-Finned Fish | The Cichlid's Tale is about adaptive radiation. Cichlids in the African Great Lakes have fast formed new species. Lake Victoria, about 100,000 years old, has as many as 450 cichlid species. Lake Victoria cichlids are distinct from Lake Malawi cichlids which are distinct from Lake Tanganyika cichlids. Yet within each lake, similar adaptations have convergently evolved. The authors quote George W. Barlow on the cause of speciation: “Genes flow but not much.” In allopatric speciation, a physical barrier disrupts gene flow, one reason islands have been so important in evolution. But any isolated environment could be considered an island. To a fish, a lake is an island, if not an archipelago A reef within the lake could be an ‘island’. Indeed, genes seem to flow within reefs but not between them. The authors recount how, by constructing an "unrooted haplotype network" with computational phylogenetics of mitochondrial DNA, Erik Verheyen, Walter Salzburger, Jos Snoeks and Axel Meyer were able to infer the time and the location of each major speciation event. Geologic evidence shows that Lake Tanganyika was once split into three lakes. Genetic evidence shows splitting into three species around the same time. All the species are ultimately derived from a single species flock from Lake Kivu. As in The Galapagos Finch’s Tale, different lines of evidence corroborate one another. |
| 20 | 430 mya | Ray-Finned Fish | The Blind Cave Fish's Tale is about Dollo's Law that evolution cannot be reversed. An exception seems to come from species living in caves. Many species, having colonized caves, have convergently evolved similar adaptations, including the loss of skin pigmentation and eyes. Different populations of Mexican tetra have separately ventured into caves, and each has evolved white skin and blindness. This can be explained by opportunity cost: resources spent on building eyes cannot be used for other things. In a cave, resources spent on eyes can be used for things more useful in that environment, and the eyes become vestigial. Another possibility is that, in the absence of selective pressure, deleterious mutations accumulate. Eyes won’t be selected for if they’re not useful in the present, even if they may be in the future. Natural selection is blind. |
| 20 | 430 mya | Ray-Finned Fish | The Flounder's Tale is about how evolution tinkers with existing body plans. When flatfish hatch, they are symmetric, with an eye on either side. But evolution has fashioned them for a life lying flat on the ocean floor. During development, the eye on the lower side migrates to the upper side. This happens whether they lie on their left or right. This asymmetry results in distortions in the skull. Dawkins discussed this in his Royal Institution Christmas Lectures, on “Designed and Designoid Objects.” |
| 21 | 460 mya | Sharks | Sharks, rays and the related animals are supported by a cartilaginous skeleton that never ossifies to become bone. Their skin is covered in dermal denticles, tiny scale-like protrusions, from which teeth may have evolved. Sharks lack a swim bladder for buoyancy and instead rely on constantly swimming, retaining urea in their blood, and having large livers with plenty of oil to remain afloat. Concestor 21 was an ancestor to all gnathostomes, animals with lower jaws, a structure which evolved from the gill arches. |
| 22 | 525 mya | Lampreys and Hagfish | Jawless and limbless fishes, the lampreys and hagfish, join the pilgrimage to meet the concestor of all vertebrates. The jawless fish and the concestor 22 are borderline vertebrates. Unlike the rest of vertebrates, they retain the notochord, a stiffening cartilage rod running along the back of an animal, well into adulthood. In all other vertebrates, the vestigial notochord appears in the embryo briefly and is replaced by segmented, articulate backbones in adults. On the other hand, both the jawless fish and the jawed fish share characteristics common to all members of the phylum Chordata at some time in their life cycle, including the notochord, pharyngeal slit, and the post-anal tail. |
| 22 | 525 mya | Lampreys and Hagfish | The Lamprey's Tale is a variation on the theme of “The Howler Monkey’s Tale”, about how gene duplication creates genetic novelty. In vertebrates, haemoglobin, the protein that carries oxygen in the blood, is composed of four globin chains, two alpha and two beta. The genes coding for haemoglobin are paralogous, derived from duplication. An ancestor globin gene from an ancient vertebrate split into two genes, which ended up on two different chromosomes. Both alpha and beta further split into more independently evolving genes. We can make a prediction: Lampreys and hagfish are ancient and predate this gene split. Jawless fish should not possess split globin genes. But they should be present in the genomes of bony fish, amphibians, reptiles, birds and mammals. That is what is found. |
| 23 | 535 mya | Sea Squirts | The lancelet and sea squirt have been switched in the second edition based on DNA studies. A sea squirt resembles a sedentary bag of seawater anchored to a rock. It feeds on food particles strained from water. Anatomically, the sea squirt looks very different from the joining pilgrimage of all vertebrates and protochordates, that is, until its larvae are examined. The sea squirt larva looks and swims like a tadpole. It possesses a notochord and a dorsal nerve tube and moves by undulating its post-anal tail from side to side. Vertebrates may have branched off from ancient sea squirt larvae via neoteny, in a process reminiscent of The Axolotl's Tale. But recent DNA analysis on larvaceans favours Darwin's initial interpretation, that one branch of ancient tadpole-like protochordates evolved a new metamorphosis stage to turn into sedentary sea squirts. Sea squirts have some of the fastest recorded rates of molecular evolution. |
| 24 | 540 to 775 mya | Lancelets | Lancelets are a text book example of a chordate. Equipped with a notochord, a nerve tube on the dorsal side and gill slits, they typify the phylum Chordata. But lancelets are not primitive nor our remote ancestor. They are as modern as all other members in the pilgrimage. |
| 24 | 540 to 775 mya | Lancelets | The Lancelet's Tale continues to develop the theme introduced in The Duckbill's Tale, that all living animals have had equal time to evolve since the first concestor, and that no living animal should be described as either lower or more primitive. The authors extend this concept to apply to fossils as well. Even though it is tempting to label fossils as our remote ancestor, they are more accurately described as our distant cousins who have been frozen in time. |
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".| Rendezvous point | Time | New Pilgrim | Story | - |
| 25 | 550 mya | Ambulacrarians | This diverse group includes the echinoderms, along with some organisms labelled "worms" and even Xenoturbella, which until 2016 could not be classified at all, but analysis of its genes finally established its position as a distant relative of the echinoderms. | - |
| 26 | 560 mya | Protostomes | The protostomes join the deuterostomes, and this joint is the originator of the kingdom Animalia. Protostomes and deuterostomes are based on the way animal embryos diverge after gastrulation where the blastula indents to form a cup. In the sub-kingdom of protostomia, the indentation eventually becomes the mouth. In deuterostomia which includes humans, the indentation eventually becomes the anus; the mouth is formed later. This ancestor is sometimes referred to as Urbilaterian. This brings in the Insecta which represent three-quarters of all animal species on Earth. | - |
| 26 | 560 mya | Protostomes | The Ragworm's Tale is about the evolution of left-right symmetry in bilaterians. Dawkins discusses the evolution of eyes, thought to have happened as many as 40 times convergently. Despite the diversity of eyes, the same genes control their development in different species, for reasons seen in The Fruit Fly's Tale. | - |
| 26 | 560 mya | Protostomes | The Brine Shrimp's Tale is about its proclivity for swimming upside down, which it shares with fairy shrimp. Dawkins suggests that natural selection favors individuals who learn a behavior, and that genes “catch up.” He asks how it is that animals come to distinguish up from down. It seems to be an instinct, as Dawkins’s graduate work showed. The moral of the story is that evolutionary changes may start as learned behaviors that are reinforced by natural selection. | - |
| 26 | 560 mya | Protostomes | The Leaf Cutter's Tale is a variation on the theme of the Farmer’s Tale. Fungus-growing ants of the genus Atta independently invented agriculture, long before humans, by domesticating fungi and harvesting their gongylidia. Several species of ants have independently domesticated aphids. The moral of the story is delayed gratification as the basis for agriculture. | - |
| 26 | 560 mya | Protostomes | The Grasshopper's Tale talks about the futility of discriminating between races. | - |
| 26 | 560 mya | Protostomes | The Fruit Fly's Tale is about embryology. It is a variation on the theme of The Mouse’s Tale, about how genes control development. A handful of Hox genes control development in almost all animals. The body plans of mice, men and fruit flies are found in Hox genes, laid down in the same order on chromosomes in all species since Concestor 26. | - |
| 26 | 560 mya | Protostomes | The Rotifer's Tale is about the evolution of sex. The bizarre bdelloid rotifer reproduces via parthenogenesis. Through mitosis, they produce eggs which yield genetically identical daughters. Mark Welch and Matthew Meselson have found that rotifers have been asexual for millions of years. John Maynard Smith called this “an evolutionary scandal.” The authors write that sex may be the real scandal. Why do we do it? One answer comes from the Red Queen hypothesis, that organisms are engaged in an evolutionary arms race against parasites. Sex creates the variation that is the raw material for natural selection. | - |
| 26 | 560 mya | Protostomes | The Barnacle's Tale is about how appearances can be deceiving, as Darwin discovered through long study. Barnacles, as their larva stage reveals, are crustaceans. Perhaps the most bizarre barnacle is Sacculina, which is as a parasitic castrator of crabs. | - |
| 26 | 560 mya | Protostomes | The The Velvet Worm's Tale is about the Cambrian explosion. In the epilogue, the authors expound on the molecular clock method used throughout the book, Motoo Kimura's neutral theory of molecular evolution and Tomoko Ohta's nearly neutral theory of molecular evolution. As seen in The Gibbon's Tale, the genetic code is redundant, as many codons code for the same amino acid. A synonymous substitution will be invisible to natural selection but not to biologists.. | - |
| 27 | 570 mya | Acoelomorph Flatworms | Still under debate on how this group fits in due to a long period of molecular evolution similar to the Gibbons Tale. These flatworms lack an anus or a coelom. The organs do not sit in a coelom but a parenchyma and is the reason for the name of the group. | |
| 28 | 590 mya | Cnidarians | The Jellyfish's Tale discusses how some underwater organisms migrate between different depths due to day and night cycles. | - |
| 28 | 590 mya | Cnidarians | The Polypifer’s Tale is about the formation of coral reefs. Corals are symbionts with zooxanthellae, photosynthetic algae, and as such grow in shallow waters. How do barrier reefs form in deep ocean? Darwin discussed this in his first scientific book, The Structure and Distribution of Coral Reefs. He suggested that the seafloor subsided. His theory still stands, and the subsidence is explained by plate tectonics. | - |
| 29 | 600 mya | Ctenophores | It is not completely clear whether Ctenophora should be placed here as an outgroup to all animals and actually at rendezvous 31. But this would mean that they either independently invented muscle, nerves, cell layers or that the sponges lost them: only 100 species but quite numerous. DNA studies are also complicated by incomplete lineage sorting like with the Gibbon. | - |
| 30 | 620 mya | Placozoans | Only one species identified. It looks like a multicellular amoeba. | - |
| 31 | 650 mya | Sponges | The last animal of the chain. Do not move but have a coordinated movement between cells. Also, seems to be two lines of sponges based on molecular data. Sponge cells are totipotent. | - |
| 31 | 650 mya | Sponges | The Sponge's Tale is about multicellularity. In 1907, Henry Van Peters Wilson separated a sponge into its component cells with a sieve. The sponges reassembled themselves. The authors suggest this sheds light on the origin of metazoans. | - |
Non-animal eukaryotes
There are essential differences between the 1st and 2nd editions of the book in this section. Another rendezvous has been added, and the unknown rendezvous has been partially resolved.| Rendezvous point | Time | New Pilgrim | Story |
| 32 | 800 mya | Choanoflagellates | The Choanoflagellate's Tale is about the evolution of multicellularity. Choanoflagellates are the closest living relatives of the multicellular animals, and can form temporary colonies from a free-living unicellular stage. Sponges have choanocytes, cells that resemble single-celled choanoflagellates, providing an indication about how multicellularity may have evolved. This common ancestor is sometimes called urmetazoan and several theories have been developed on its evolution. |
| 33 | 900 mya | Filastereans | New addition to 2nd edition based on 2008 work. Pushes all others back one. |
| 34 | 1000 mya | DRIPs | The acronym comes from the letters of the four genera that were first known. These are single-cell parasites of fish and other freshwater animals. DNA sequencing has added about 50 species. Of course, this concestor could not have been a parasite of a fish. |
| 35 | 1200 mya | Fungi | Only 99,000 of the 4 million estimated species have been identified. |
| 36 | Uncertain | A protozoan grouping called Apusozoa made up of 3 protist groups breviata, ancyromonads and apusomonads. | |
| 37 | Amoebozoans | 'Amoeba' is a description rather than a classification because many unrelated eukaryotes exhibit an amoeboid form. | |
| 38 | Very large group of light harvesters and their kin: excavates, SAR supergroup, 20 species of single-celled glaucophytes, over 4,000 species of red algae, and hundreds of thousands of species of green plants. | The Cauliflower's Tale is about Kleiber's law. Gometrical considerations of constructing the most efficient supply tube network in tissues dictate a scaling exponent of 3/4 for such different structures as cauliflower and our brain. | |
| 38 | Very large group of light harvesters and their kin: excavates, SAR supergroup, 20 species of single-celled glaucophytes, over 4,000 species of red algae, and hundreds of thousands of species of green plants. | The Redwood's Tale is about dendrochronology. It goes on to explain different methods of radiometric dating such as Uranium–lead dating and Potassium-argon dating and Carbon dating. | |
| 38 | Very large group of light harvesters and their kin: excavates, SAR supergroup, 20 species of single-celled glaucophytes, over 4,000 species of red algae, and hundreds of thousands of species of green plants. | The Humped Bladderwort's Tale is about the C-value paradox, that the size of an organism’s genome does not correspond to complexity. In 1983, Barbara McClintock won the Nobel Prize in Physiology or Medicine for her discovery of transposons, genetic elements that cut and paste themselves through the genome. The C-value paradox is resolved by differences in the number of transposons. The Humped Bladderwort has managed to delete most of its parasitic DNA. This may be because a paucity of phosphorus, a key element of DNA, created selective pressure to economize production of the molecule. In primates, the most common parasitic element is Alu. Presumably, it emerged between Concestors 9 and 10. | |
| 38 | Very large group of light harvesters and their kin: excavates, SAR supergroup, 20 species of single-celled glaucophytes, over 4,000 species of red algae, and hundreds of thousands of species of green plants. | The Mixotrich's Tale is about symbiosis. Mixotricha paradoxa translates to ‘unexpected combination of hairs’, so named by J. L. Sutherland because she thought it had both cilia and flagella, not thought possible in protists. In fact, they are not cilia, but bacteria, specifically spirochaetes, which serve Mixotricha as ‘galley slaves’ in S. L. Tramm’s phrase. Mixotricha is itself a symbiont, helping its host digest cellulose. It lives only in the termite Mastotermes darwiniensis. |
Great Historic Rendezvous
This is a significantly shorter section in the second edition. The authors describe the critical beginnings of eukaryotic cells and describe the endosymbiotic theory proposed by Lynn Margulis.Prokaryotes
Prokaryotes lack a cell nucleus. They can move genetic material between unicellular and multicellular organisms via horizontal gene transfer.| Rendezvous point | Time | New Pilgrim | Story |
| 39 | Archaea | Carl Woese proposed Archaea as a distinct Kingdom, apart from Eukarya and Bacteria. Archaea have metabolic pathways more closely related to eukaryotes such as the enzymes involved in transcription and translation. | |
| 40 | Eubacteria | The Rhizobium's Tale is about the evolution of the bacterial flagellum, likely from a Type II secretion system. The authors note that, despite the diversity of animal body plans, wheels seem only to have evolved once, in these humble organisms. | |
| 40 | Eubacteria | Taq's Tale is about the thermophilic bacteria Thermus aquaticus, which lives in near-boiling waters such as the Grand Prismatic Spring of Yellowstone National Park. It is beloved by biologists as the source of the enzyme Taq polymerase, used in polymerase chain reaction. |
“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 and store information, 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”. He notes that eyes have evolved as many as twenty times convergently. Several species have evolved gliding, including 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.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.”
Reception
of the New York Times stated that the book is one of the best to understand evolutionary trees.The Guardian thought it was awkward to move backward in time starting from humans and thought this required linguistic gymnastics with new definitions of before and after a certain evolutionary point. Matt Ridley, in the same publication, appreciated the approach of a Chaucerian Pilgrim traveling backwards and the perspective of not seeing other animals as failures.
Jody Hey notes that Dawkins “writes engagingly on evolutionary topics. With a highly self-assured style, he effortlessly draws insightful connections among disparate notions, trapping the curiosity of readers before they know what’s coming.” However, he says “An unfortunate editorial oversight is seen in the text’s occasional straying into political commentary. Worse still, Dawkins at one point chastises Richard Lewontin, the great population geneticist, for sometimes interjecting politics into scientific discourse. This little touch of hypocrisy is hard to miss if you read the entire volume. But such lapses amount to a few dozen words in a weighty, truly wonderful book.”
Steve Jones calls it “a rigorous and impressively complete account of the Tree of Life… The Ancestor's Tale achieves the almost impossible: it makes biology interesting again. Everyone possessed of a cell nucleus should read it, and ponder their own unimportance. One mystery remains: what did the star-nosed mole say to the duck-billed platypus?”
Translations
| Edition | Name | Translator | Year |
| Bulgarian | Сказанието на прадедите | Krassimira Mateva | 2013 |
| Chinese | 祖先的故事 | Gu Xiaozhe | 2020 |
| Czech | Příběh předka | Pavel Růt | 2008 |
| Danish | Vores forfædres fortælling | Lotte Follin | 2019 |
| Dutch | Het verhaal van onze voorouders | Mark van Nieuwstadt | 2007 |
| French | Il était une fois nos ancêtres | Marie-France Desjeux-Lefort | 2007 |
| German | Geschichten vom Ursprung des Lebens | Sebastian Vogel | 2008 |
| Hungarian | Az Ős meséje – Zarándoklat az élet hajnalához | Kovács Lajos | 2006 |
| Italian | Il racconto dell'antenato | L. Serra | 2004 |
| Korean | 조상 이야기 | Lee Han-eum | 2005 |
| Persian | داستان نیاکان | ||
| Polish | Opowieść przodka | Sobolewska Agnieszka | 2018 |
| Portuguese | A grande história da evolução | Laura Teixeira Motta | 2009 |
| Spanish | Historia de nuestros ancestros | Víctor Vicente Úbeda | 2008 |
| Turkish | Ataların hikâyesi | Ahmet Fethi | 2015 |
| Serbian | Priče naših predaka | Tatjana Bižić | 2013 |
| Russian | Рассказ предка | S. I. Dolotovskaya | 2015 |