The Ancestor’s Tale

Title: The Ancestor’s Tale – A Pilgrimage to the Dawn of Life

Author: Richard Dawkins

Publisher: Phoenix, 2005 (First published 2004)

ISBN: 978-0-7538-1996-8

Pages: 629

A huge, but thoroughly informative work from Richard Dawkins, with additional research by Yan Wong. It is a kaleidoscope of the events on earth right from life’s beginnings billions of years ago to today’s sapient individuals in the form of modern humans. Modeled on Geoffrey Chauser’s Canterbury Tales, the narrative is portrayed as a pilgrimage to the past where the representatives of modern species go backward in time, meeting representatives of more basic ancestors of themselves. The journey goes down across millions of years until the nucleated cell emerged. It depicts in pictorial detail the similarities which underscore the common origin of all lifeforms and shows how small changes in individual genomes accumulated over many generations resulted in the emergence of a new species, which is the essence of Darwin’s evolutionary theory. Dawkins is sometimes referred to as an ultra-Darwinist, an accusation not denied by the author himself. He is the most prominent figure in the fight against regressive forces propounding creationism or intelligent design, wasting no chance to lampoon the fallacy of these arguments.

When we look at lifeforms which inhabited the earth prior to man’s appearance, it is conceivable that we tend to look upon them (or rather, look down upon them) as creatures which are intermediate between the origin of life and the appearance of man, which many of us take to be the crowning glory of nature. Before proceeding on his pilgrimage to the dawn of life, Dawkins warns us not to don such ‘hindsight’. Every organism which occupied the earth for a considerable time were perfectly adapted to its environment just like man is to his. In contrast to other tales of evolution, this book takes a backward-going journey from the present to the origins. Representative of each living group goes back and meets other cousin groups at several points on the way, when the lineage split into two at a previous age. Dawkins uses the term, concestor, to denote a common ancestor of more than one species of animals. Forty such concestors are identified on the entire journey.

Naturally, we’ll be interested more in the evolutionary pathways of our own species. There is irrefutable fossil evidence that modern humans and Neanderthals, a related human subspecies lived alongside each other in Europe as late as 30,000 years ago. The lot of modern humans had somewhat flourished suddenly at around 40,000 years ago which many anthropologists refer to as the ‘great leap forward’ (not to be confused with Mao’s program). This is evidently the development of speech or the use of complex conditional statements in language which opened up whole new vistas for human imagination and progress. Going back a little further, we see humans emigrating out of Africa at 100,000 years ago. This has caused a controversy among scholars. There is a large proportion of them who believe that the present day’s population of the world are the descendants of these emigrants from Africa and is called Young African Origin. There are others who maintain that there were several migrations tuned to the waxing and waning of previous ice ages who might have cross-bred with already existing humans in other parts of Asia. It is called ‘Old African Origin’ and cite it to be the reason behind racial differences across populations. One thing is sure, that all humans originated in Africa and only the date of migration is in question. When we reach around one million years ago, we come across Homo erectus which are hominids. At six million years ago, we meet our common ancestor with chimpanzees and bonobos, which are man’s closes cousins. At 7 million years ago, gorillas join the team.

Going further back, monkeys join the bandwagon. There is a marked difference between apes and monkeys that the former don’t sport a tail and are mainly bipedal. Arguments vary about the origin of bipedalis, ranging from increased height to sexual advantage. Also, full colour vision developed in apes as compared to most of Old World monkeys. Similar faculty occurs in the howler monkeys of the New World which probably evolved genes for colour vision in the same way as apes did. The concestors of all apes and primates probably pre-date the Great Cretaceous extinction which ensured the demise of large reptiles like dinosaurs. Ancestors of all mammals might have been nocturnal until then, but when the competition was suddenly removed, they gradually filled every niche vacanted by dinosaurs. Development of colour vision ensued the conversion to diurnal animals.

Opponents of evolution often argue that if the modern lifeforms evolved from ancient forms, the intermediate forms should have been present all the way to modern times. When evolution spans geological time periods, intermediaries are not easily discernable since most of them must have died out. Dawkins presents a parallel idea to show that speciation (the process of a species metamorphosing into another) is a continuous process. He suggests the case of salamanders of California valley as the test species. The valley is longer than it is wide, with mountains on both east and west which is joined at the north and south. The salamanders cannot cross the vally east to west or west to east, but they could propagate north-south or south-north through the mountains. We now see that there are two subspecies at the southern end, the eschscholtzii and klamberi which don’t interbreed on the west and east respectively. However, both the species can breed with their neighbours immediately on the north. When we go north on both sides, we see changes in the characteristics of salamanders when compared to those at the extreme south. All of the subspecies can interbreed with their neighbours in an uninterrupted sequence along the ring of mountains, but when the starting point is reached again, the changes accumulated over the journey has resulted in two species which don’t interbreed. In other words, all the salamanders on the north are intermediates between the two species at the extreme south. Evolution proceeded likewise and the example is a powerful one.

As we go back to the misty dawn of life, we lose track of time. Before 500 million years, the methods of time reckoning diverge to senseless numbers. Continuing the pilgrimage back, we reach a point which Dawkins calls the Great Historic Rendezvous, the time at which the first eukaryote (nucleated cell) emerged. The cell then gradually grew by itself and in symbiotic relationships with other cells. Cyanobacteria were able to convert sunlight to useful energy by photosynthesis. Oxygen, which was the byproduct of this reaction was a toxic gas, but mitochondria adapted to convert it to useful energy. Chloroplasts ended up in plant cells while mitochondria migrated to animals, including us, which are still the powerhouse of the cell. Dawkins also addresses the issue of how life itself emerged. Preservation of heredity was the key event which was realized by self-replicating chemicals out of which DNA emerged. Life is hypothesized to have begun in deep underground rocks which have a very high temperature in the form of thermophile bacteria. If life replayed its growth again from the beginnings, there is no assurance that the same path will be followed. However, some aspects of evolution, like eyes, is sure to appear again as some form of vision has independently evolved not less than 40 times in the animal domain.

The book is arranged in a structured way, with lots of colour plates. One must wonder at is the comprehensive coverage of life depicted in the various chapters. It spans all classes, habitats and time periods. The author’s great knowledge of biological systems is effectively demonstrated in substantiating his arguments. Spanning 629 pages, this book is really worth to possess.

Too many footnotes play the spoilsport in many pages. To clarify some other related point, the author has not hesitated to include as much footnotes as he thought fit. This may be useful, or in fact essential, in an academic publication, but definitely not in a book aimed at the general public. Paradoxical it may seem, but the book is an out and out biological one, while readers with backgrounds in other disciplines may find it difficult to digest the concepts and even to fully develop a working familiarity with the taxonomical finer points. Also, lay readers may get a feeling that after the human concestors are passed in the tale, the journey becomes a bit tedious and fails to rivet their attentions consistently.

The book is highly recommended.

Rating: 4 Star