Friday, 13 April 2018

Who We Are and How We Got Here

Oxford University Press 2018
ISBN 978-0-19-882125-0
In little more than a decade, studies of ancient DNA have transformed our knowledge of human history. A recurrent theme is the migration of people over long distances to mingle with and often to replace existing populations. Often the immigrants brought with them new technologies and languages. Although there are also examples of skills dispersing without migration (spread of the Beaker culture from Iberia) and succesive waves of migrants adopting local languages (southwest Pacific islands).

All this and much more is related in David Reich's new book. Although his prose is stilted at times, that is more than compensated by the breadth of material presented and by excellent diagrams. These include maps showing the probable origin, direction and timing of human migrations. 

Skull from Lapa Vermelha, Lagōa Santa, Brazil
Photo by Ryan Somma CC BY-SA 2.0
Although Reich delights in disproving established concepts, it is interesting to find that some long-standing ideas receive support. For example, there is a clear genomic evidence of two waves of migration into Central and Southern America. The first wave of migrants designated "Population Y" left a genetic signature that is strongest in some isolated Brazilian communities (Tupí). This finding lends support to the concept of an ancient people called Palaeoamericans by Neves (here) and named a century ago as Palaeo-Amerind by Haddon (previous post). These ideas were fostered by excavations at Lagõa Santa, Brazil, started 175 years ago by the Danish scientist Peter Lund and continued until this day.

Similarly, present day peoples of India derive much of their genetic makeup from two previous populations. One of these described as "Ancestral South Asians" bears a striking resemblance to the "Pre-Dravidians" postulated by Haddon.

There has been some animus engendered by Reich's book - exacerbated by an opinion piece he wrote for The New York Times. Part II of the book has chapters on the origins of Europeans, South Asians, Native Americans, East Asians and Africans. Inevitably this division reflects the broad racial categories of the past. The flight from racial stereotyping in the last 50 years is laudable, but a mist of political correctness can make recent studies hard to decipher. Reich's book disperses the mist and inevitably invites controversy.