The Origin of Our Species

Title: The Origin of Our Species

Author: Chris Stringer

Publisher:  Allen Lane, 2011 (First)

ISBN: 978-1-846-14140-9

Pages: 273

Meritorious books on the subject of human origins are rare in literature owing to the still fluid state of knowledge. New discoveries of fossil remains come out all the time, forcing paleontologists to run for cover and justify their long-held positions. This book is a extraordinary one of the sort. Chris Stringer is a foremost British expert on human origins and works at the Natural History Museum in London. He has authored many books on human origins and this is his latest offering.

Remains of primitive human fossils were found from Africa, Europe, Indonesia and China. Africa was late entrant into the picture and it was thought before that humanity originated in many places, with a multi-regional theory gaining hold. Upon discovery of more ancient and widely varied humanoid species in Africa in the 20^th century, and analyses of DNA has now led the scientific community to postulate that humans originated there and spread out to various regions. Interbreeding and hybridization with primitive humanoids are issues hotly debated among academic community.

Stringer presents an illuminating discussion on dating techniques and other revolutionary breakthroughs occurred in paleontology. By establishing the ratio of isotopes, researchers are now able even to identify the diet of the person under study. Application of this wonderful technique on the fossils in Europe and Asia of Neanderthal and Cro-Magnon men (modern man) show that the former solely or heavily relied on meat (of reindeer, mammoth, byson and horse), while the latter also used fresh water fish in all their currently identified habitats. The increased efficiency in nutrient intake might have helped modern men to gain the ascendancy. A curious fact in connection with dating is that just like trees put on annual rings in its trunk, similar rings develop on human dental enamel, which is accumulated on a daily basis. Called perikymata, these provide valuable information on the age of the person while he died.

Apart from physical parameters, changes in behavioural patterns played a central role in humans making the advent. A fact which helped humans in earlier divergence from primates is the change in colouration of the outer covering of eye ball (sclera). For most primates, it is dark brown while it is white for man. This helps his colleagues to gauge the movement of his eyeball precisely in a social setting. This, in a sense, helped others to mind-read colleagues and also to convey signals through eye movement. Such facility naturally led to heightened ability to control thoughts, emotions and actions, to plan far into the future and to evolve self-consciousness. The resultant cohesion helped the ancient men a great deal to hunt in groups and outwit the stronger though dull prey.

Though scientists differ on the time a great revolution occurred in the human brain (in its organisation, not size) which seeded the growth of domestication of animals, composite tool making and highly complex social life. The brain size of man already matched his 21^st century counterparts by 200,000 years ago. In fact, its size was a little bigger than moderns, but their physical sizes were bigger too. What is important in the case of brain is the ratio of its volume to body mass, called Encephalization Quotient (EQ). Otherwise, elephants which have bigger brains than man would have been the cleverest. The ratio was 3.4 to 3.8 for Homo erectus, 4.3 to 4.8 for ancestors of modern humans and Neanderthals and 5.3 to 5.4 for earley moderns. The figure has levelled off or slightly declines for late modern humans. Probably, we get away with reduced intelligence with the help of technology and cultural progress, which was not the case for a primitive man struggling for his existence in the wild. So, the physical change in brain size for early moderns was accompanied by reorganization of the brain around 40,000 to 50,000 years ago. This mutation might have occurred as a result of wild climatic swings, probably in the wake of Toba supervolcano’s eruption around 73,000 years ago in current Indonesia. The physical as well as behavioural modernity made us what we are today. However, elements of modernity, like body colouring and composite tool making found in Neanderthals and DNA analyses suggest that people in Europe, Asia and New Guinea share at least 2% of their genomes with Neanderthals. It also indicates interbreeding with them when the first individuals of early moderns migrated out of Africa. These people, when bred with next wave of migrants out of Africa carried the mixed genes to other parts of the world except Africa, which still presents the purer samples of human DNA. Sharing genes of another ancient human lineage, the Denisovans, by modern Melanesians people (as much as 6%, in this case) shows that admixture occurred even far away from Africa.

Stringer presents a good case for why the florescence in technology and social skills developed. Too few population density stifles growth due to lack of competition. Evolution needs a large population size to use its tools on. Closely spaced groups with moderate population densities, competing or cooperating with each other for resources and mates provide the ample social setting for brain development. The climatic setting was provided by global warming up at the end of last Ice Age around 20,000 years ago. Language helped a great deal in ensuring a positive feedback mechanism. Evolution has not stopped since modern man originated. Genetic variation among regional populations attest to this fact.

Being a very recent work, the book describes many new discoveries of ‘missing links’ – the weapon with which creationists attack evolution. These are gradually filling up the gaps in fossil record, lending a hand to evolution to become a watertight theorem to dangle in front of clumsy admirers of a divine being bent on creating the world. The book is also remarkable for its great sincerety, great knowledge and the great effort. Whenever the evidence is not up to the mark, Stringer doesn’t mince words to suggest that even his own research findings must have to be evaluated in a new light. The book is well structured and elegantly written. However, it is too technical to appeal to the general reader. Detailed description of cranial features and other anatomical peculiarities are too cumbersome and uninteresting. Words like iliac pillar and pubic ramus scare people away! Overall we feel that the author has missed a great opportunity by not scaling down the level of erudition digestible by the lay reader.

The book is recommended for serious enthusiasts.

Rating: 3 Star