Sunday, May 4, 2003		Books

Update on man’s journey till date
Peeyush Agnihotri

The Journey of Man — A Genetic Odyssey
by Spencer Wells. Penguin Books. Pages 224. Rs 495.

THE evolution of man has since long been an enigma. Be it the field of anthropology, paleontology, eugenics, biology, or more recently biotechnology, everything helixes down to DNA and eventually tries to solve the puzzle of evolution.

This book attempts to unravel the past and this ‘racial’ journey that meanders through blood, bones, DNA and carbon isotope dating, is a racy one. Even though the title might suggest otherwise, sexism was the last thing on Spencer Wells’ mind when he chose it. The reason for this choice, according to the author, is that the Y chromosome inherited from Adam down the male line gives the keenest tool for establishing genetic heritage.

The book is sprinkled with a fair amount of research findings relating to genetic evolution. This can make the whole affair a bit drab, critics may say. But then, wait. Before you jump to any conclusions, look at the analogies and metaphors that the book is filled with. For example, while explaining how genes might have got corrupted while undertaking their more than 60-thousand-year-long journey, Spencer links it to bouillabaisse, a spicy fish soup from the south of France. He avers that just as the present day bouillabaisse won’t taste like it used to a few generations ago because of the numerous alterations, modifications and corruptions in the recipe, similarly the Y chromosome might not have remained what it was a few eons ago. He likens men to albatross while mating. "As long as you are on the island at the right time, you have a good chance of being lucky," is how he puts it. On a metaphorical binge, Spencer says the African Exodus was like squeezing of toothpaste through a tube.

Spencer starts off with Darwin’s journey on HMS Beagle. Darwin, the famous naturalist who had a penchant for geology, had noted how inhabitants from Tierra del Fuego were stunted in growth and had hideous faces yet were of the same species as were gauchos of Argentina. Then came Linnaeus, the Swedish botanist, who classified human species into races and subspecies like afer, americanus, asiaticus, europaeus and monstrosus (that included Darwin’s Fuegians) followed by Carleton Coon, the American anthropologist, who advanced the theory of five distinct human subspecies — Australoid, Capoid, Caucasoid, Congoid and Mongoloid. These were some of the early endeavours in the field of evolution.

Then the author takes us on craniometry and blood sampling trip. He brings to the notice of the readers that Egyptian mummies reiterated ABO blood group polymorphisms. A very important point that he puts forth is that DNA sequencing undergoes mutation every generation. This occurs at the rate of nearly 30 per genome per generation. It is because of this complete gradual mutation between 31,000 and 79,000 years ago that first Eurasian Adam, the ancestor of all non-Africans, came into existence. The latest spread of Y-chromosome lineage is known to have taken place nearly 10,000 years ago.

Spencer, on the basis of the study of mitochondrial DNA (passed on through the maternal family line) and the Y chromosome (passed from father to son), says that the modern-day man is not a descendant of Neanderthals and that the human race can trace its origin to one Adam and Eve. That Eve lived in Africa less than 1,50,000 years ago and Adam, from whom we derive our Y chromosomes, lived 59,000 years ago in Africa.

The book touches topics like Ice Age, genetic mutation, tectonic upheavals, continental bollards and Neolithic agriculture. Due to the presence of mountains, Eurasian migrants could have split into two groups — one moving to the north of Hindukush and another into Pakistan and the Indian subcontinent. It also reveals some other interesting facts. The Bushmen of Africa have some of the oldest genetic markers in the world and represent a direct link to our earliest human ancestors. Early Siberians were scavengers. All Native Americans had just 10 to 20 individuals as their founding fathers. And women moved more than men, dispersing their mitochondrial lineages among neighbouring population.

Supported by nearly 50 black and white photographs of people belonging to different races, genealogical trees and world maps, this book makes an interesting reading for those interested in knowing the past. Watson and Crick postulated the DNA model 50 years ago. This book goes into the ‘Y’ of it. Not so elementary, this Watson (and Crick).