The Journey of Man

Title: The Journey of Man – A Genetic Odyssey

Author: Spencer Wells

Publisher: Penguin Books India 2003 (First published 2002)

ISBN: 978-0-143-02995-3

Pages: 198

A really fascinating book which you can literally read cover to cover in one go. Spencer Wells is a noted researcher on genetic studies of ancient societies and has presented a lot of cutting edge theories to the audience. The book traces the journey of modern man from Africa where he originated and how he went on to colonize all parts of the world by incessant journies, surpassing all obstacles which sought to stop him. Many of the theories and ideas presented are of the colleagues and teachers of the author, so we can be assured that he is well informed of the subject learned from the masters themselves – the perks for being at Stanford, one of the world’s leading educational institutions. The book was originally conceived as part of a documentary film project of the same name.

Charles Darwin’s work, ‘The Descent of Man’ addressed the issue of the origin of humans. He considered all races to belong to a single species, with only minor physical variations. This insight is more than justified by later researchers, and Darwin’s prescience is put in greater limelight when the fact that Linnaeus, who categorized the living into species, sought to classify humans on racial lines, is considered. According to Linnaeus, the human species should be sub-divided into americanus, asiaticus, europaeus and monstrosus. The ideas were long held among the academic community, as Carleton Coon, a noted U.S. anthropologist subscribed to these views and made publications in academic circles developing on these lines by the middle of the 20^th century. This century was notorious for the racial prejudice and violence enacted on various parts of the globe. The ‘eugenics’ movement which believed that offsprings can be ‘crafted’ or moulded into desirable patterns by carefully selecting the parentage – sometimes forcibly preventing people having mental disorders to reproduce – gained ascendancy during the first quarter of the 20^th century. Francis Galton’s studies which were a forerunner to Coon, helped pave the way for the eugenics movement in Britain.

The diversity among living humans came out from the studies on blood samples by Karl Landsteiner in 1901. He categorized blood into different groups and performed studies on the genetic makeup which produced such diversity in blood groups. It was he who named the groups A, B, O and likewise. Building on this path-breaking study, a Swiss couple, named Hirszfeld conducted research on the soldiers of World War I of different nationalities and presented a theory that people of blood groups A and B represent pure populations of aboriginal humans, with group A prevalent in northern Europe and group B prominent in India. All these analyses were done before the discovery of DNA, the real genetic fingerprint, by Crick and Watson in 1953. Richard Lewontin in 1972 studied the genetic variations among different racial groups and found that 85% of the variation is within populations, 7% among populations in a race (Greeks vs Swedes, for example) and only 8% variation against different races. The sub-species theory held on for so long fell flat on its face, as a result. Studies by Luca Cavalli-Sforza and Anthony Edwards in 1964 on bloodgroups of different races suggested that Africans were the most distant from all others, while Europeans and Asians were clumped together. Further programs by Rebecca Cann in 1987 on mitochondrial DNA (mtDNA, for short) showed that all the mtDNA stem from one woman, who is postulated to have lived about 150,000 years ago, probably in Africa. Africans, as a group showed the greatest variation in mtDNA signifying that they have been evolving and diverging for longer time than the others. Analysis on fossils of the hominid Homo erectus indicates that African and Asian erectus shared a common ancestor 2 million years ago.

Like the mtDNA which is carried over from mother to daughter, the Y chromosome is handed over to the son from his father. Analysis of Y chromosomes, particulary some of the polymorphisms in it can also be used to trace the ancestral origins of populations. This chromosome is a bit different from the others, as they are seen only in males and the number of active genes in them is only 21, far short of the average figure of 1500 for the other chromosomes. The variations on the transmissive paths are well understood and when extrapolated, gave a result of 150,000 years as the time period on which it evolved from a universal father. Refined DNA experiments done in the 90s brought the date of the last common ancestor to 59,000 years before the present. Such a difference in dates of the female and male ancestors (150,000 and 59,000 years respectively) suggest that these ancient Adam and Eve might never have met! One of the limiting factors on analysis which runs the whole gamut of several millenia loses the resolution and the results also become vague. Present African populations which carry ancient lineages are found today in Ethiopia, Sudan and parts of eastern and southern Africa, around its rift valley. The San people in Namibia is a particularly favourite candidate for being the ancestors of the entire modern humans. Their language incorporates clicking sounds which some scientists believe might have been the precursors of the development of speech in modern humans. Similar ‘click’ languages are also seen in parts of east Africa. From these tribes and indications from fossils, we may deduce that the common ancestor might be of the same average height as most of the humans are today, with dark skin (but not as dark as typical Africans), thin, perhaps with an epicanthic fold (thickening of skin above the eyes).

Thus we can be reasonably sure that human migration started from Africa 60,000 years ago probably due to a change in climate which drove the inhabitants out of it. But, the human remains unearthed from Australia are also dated to a period not very later than this time. The early humans might have followed a coastal route along the Asian landmass and hopped over some of the islands in south east Asia. Since the world was under an ice age, the sea level was tens of metres below the present level and the sea crossing might not have been that difficult as it may seem to be at present. Following the sea route is crucial as no other path would have ensured the same climate, food availability and the same tool kit. Even about 6000 years ago, south east Asia was largely inhabited by Negrito people. A case in point is the Onge and Jarawa tribes of Andaman Islands who may be called the living fossils of a bygone race. The migration to Australia is not well corroborated by evidence from India, as the archeological finds were dated to only 40,000 years. The author suggests that the Indian coasts through which the ancients travelled might be several metres below sea level at present and what remains found so far might have been that of the people who ventured inland for better prospects.

What exactly prompted the forefathers from issuing out of Africa in a so called, ‘Great Leap Forward’, 60,000 years ago? Apart from climatic pressures, development of language during this time caused greater social cohesion and complex organised behaviour, making them masters of group hunting. The development of language might have been caused by a beneficient mutation in the DNA. Migration from Africa displaced the Neanderthals (another human species) from their homelands in Eurasia. This displacement may not be entirely due to the extermination at the hands of the newcomers, but the scarcity of food due to onset of ice age would have caused excess pressure on them. Early humans settled in the Middle east and moved along the steppes and split into two groups at the Pamir Knots, one group going north to central Asia and the other going south to India. The central Asian group further split into three, with one set destined to China, the other to Europe and the third through Bering landbridge to the Americas. The Indian group is marked by a genetic marker named M20 in the Y chromosome which is found in 50% of the people in south India. This group might surely have come in contact with the people of the early wave (Australian march) and might have decimated them.

Before extensive genetic studies were carried out, there were prominent anthropologists with the view that Europeans were evolved separately from the Neanderthals. Svante Paabo and Matthias Krings provded definite proof to the contrary by their study of mtDNA of Neanderthal fossils and established that these two species shared a common ancestor only about 500,000 years ago. The Neanderthals were scattered into smaller groups and the social behaviour were not well improved. The rising population levels among the modern humans ensured a positive feedback for further growth by making available more people to care for the child while the parents can be ‘gainfully’ employed elsewhere! Presence of older people around and grand-mothering helped the human society immensely.

Archeological evidence from Clovis sites suggests that human settlements were not present in north America earlier than 15,000 years. The central Asian hunters who crossed over to Alaska around 40,000 years ago might have been stopped there due to heavy glaciation in the ice ages. This prevented from going south of the continent and the thawing around 20,000 years towards the end of the ice age cleared their way to create settlements in the American mainland. Judging from the narrow variety of the DNA variations, the author claims that at most only a few hundred immigrants might have crossed the Bering landbridge. Many giant land mammals were made extinct by excessive hunting. The wooly mammoth and the horse were among them and the horse was reintroduced into the Americas by the Spaniards after Columbus discovered America in the 15^th century. A second wave of migration might have happened from China. Thus, by 10,000 years all continents were mastered by the human race.

Around this time, another ‘Great Leap Forward’ materialized. The last ice age ended and the resultant precipitation and availability of moisture helped agriculture to spread mainly in the Middle east and China. The fashion soon spread to the Mediterranean rim and copied by barbarians from inner Europe. Rice was domesticated in China and carried by the farmers to various corners of south east Asia in another wave of migration which displaced the earlier Negritos inhabiting there. With agriculture began the neolithic age. Population exploded due to the sedentary lifestyle, but the death rate was also higher due to the prevalence of infectious diseases due to increased population and close proximity to animals. Moreover, as the wealth increased, warfare among different tribes also grew in sophistication and fatalities. Hence, the farmers died younger than the hunter gatherers, but the numbers were kept up because of higher birth rates. Development of culture and language families also happened around this time. A proto-Indo European language originated in the steppes of southern Russia which covered most of Eurasia. A genetic marker named M17 found commonly among people from the Czech Republic to Altai mountains in Siberia are also seen in a majority of Indians speaking Indo-European languages, suggesting massive ingress from Central Asia during the last 10,000 years.

After completing the odyssey the author discusses the melting pot of modern world in which people from various races mix indiscriminately, thus seriously compromising future research in this field. The lament seems to be purely academical and no racist intonations are discernible. Since any genetic test on any individual in a cosmopolitan country like the U.S. is sure to present the same genetic markers, the variation among different nationalities will be lost. While this may be blissful for the greater unity of the human race, it might sound the death knell for such fields of study.

The book is so easy to read and understand. Wells has a knack of riveting the reader’s attention to the points which he narrates in so clear detail. The navigation between various chapters is seamless attesting to the origins of the book in a video documentary. This is a must-read for everybody. The drawbacks which can be pointed out is quite few. The monochrome plates featuring people of various races are not titled, causing the reader to flip to the index page frequently where it is listed. The images shown are not very impressive and we might wonder why some of them are included in the first place! Also, the author passes opinions on sociological issues researched only poorly. Thus we see him announcing that women in India could change castes in India’s caste-system which is nowhere near the actual state of things. Wells depends greatly on the works of his teacher Luca Cavalli-Sforza and quotes extensively from his works. And, his references are mainly his own colleagues thereby reducing the variation in reference material.

The book is highly recommended.

Rating: 4 Star