“The breakthrough that all archaeologists have been waiting for; a truly exciting account of the way in which ancient DNA is making us rethink prehistory. Essential reading for everyone interested in the past.” Barry Cunliffe
“In just five years the study of ancient DNA has transformed our understanding of world prehistory. The geneticist David Reich, one of the pioneers in this field, here gives the brilliantly lucid first account of the resulting new view of human origins and of the later dispersals which went on to shape the modern world.” Colin Renfrew
Regular readers of this blog will know that my interest in ancestry, DNA and population genetics has been personal and professional (including publishing several articles and visiting the USA on a scholarship). So, it was with great anticipation I waited for Who We Are and How We Got Here: Ancient DNA and the new science of the human past (2018) by David Reich, devouring it hot off the press.
Reich, a Harvard geneticist, is in the process of cataloguing 50,000 years worth of genomes by sequencing the DNA found in ancient bones. He crunches numbers. Significantly, his team pioneered statistical methods that unravelled how Neanderthals and Denisovans interbred with modern humans (my own DNA* indicates ancestry with ancient hominin populations). The science, politics and ethics of this ‘new science’ is interwoven superbly by the author to craft a narrative of great interest to both the lay person and expert.
“To understand why genetics is able to shed light on the human past, it is necessary to understand how the genome – defined as the full set of genetic code each of us inherits from our parents – records information.” David Reich
The first book I ever purchased, from the book orders in kindergarten, was They Turned to Stone. The deep past (all history really) has been a lifelong source of fascination. In recent years, I have read enthusiastically about the science of DNA from a range of perspectives. One imagines most people who pick up this tome will have had similar reading habits. Reich’s book, although it does not assume vast amounts of pre-knowledge and complex concepts are well-explained and supported with cleverly designed graphics, will potentially be a challenge for those not having a (popular) science background or being reasonably well-versed with history. The table of contents provides a sense of what Reich covers in this very multidisciplinary field:
Part I – The Deep History of Our Species
1: How the Genome Explains Who We Are
2: Interbreeding with Neanderthals
3: Ancient DNA Opens the Floodgates
Part II – How We Got to Where We Are Today
4: Humanity’s Ghosts
5: The Making of Modern Europe
6: The Collision that Formed India
7: In Search of American Ancestors
8: The Genomic Origins of East Asians
9: Rejoining Africa to the Human Story
Part III -The Disruptive Genome
10: The Genomics of Inequality
11: The Genomics of Race and Identity
12: The Future of Ancient DNA
Although the introduction and Part I are excellent, they mostly cover territory I know well. I did note Reich’s dig at National Geographic’s Genographic Project, saying “…it was outdated before it began” and “produced few interesting scientific results”. However, I think it likely the author would acknowledge the role this project played in popularising population genetics to many people, including myself. Parts II and III are mostly very interesting. The chapters I read twice included “The Making of Modern Europe” and “The Genomics of Race and Identity”.
Europeans are the descendants of at least three major migrations of prehistoric people. The final wave, about 5000 to 4800 years ago, the Yamnaya culture, were nomadic herders from the grassland steppes of what we we now know as Russia and Ukraine. Incredibly mobile, through mastery of horse and wheel, with skills including metallurgy and herding, they spread like “wildfire”. The probability that their speech was the source of all of today’s 400 Indo-European languages will likely be resolved in the next decade.
These people interbred with descendants of the first two migrations into Europe (the hunter-gatherers and farmers) and within a few hundred years the Yamnaya contributed a very large percentage of Europe’s genetic ancestry. Another fascinating chapter explores the migrations of these steppe peoples into India, 4,000 years ago, bringing their language to the subcontinent. The evidence from this new science parallels events described in the canonical, 3,500-year-old Sanskrit book of hymns, the Rig Veda.
During the first year of the 21st century I read Luca Cavalli-Sforza’s, Genes, Peoples, and Languages and now know that Reich – who calls this Italian scientist “a visionary” – was inspired and mentored within “the school” of this influential population geneticist. This explains Reich’s stellar progress and deep interest with linguistics.
“What would those protesters think of what my laboratory is doing now grinding through the bones of hundreds of ancient people every month?”
Reich does not shy away from examining the challenges, ethics and politics of where research leads his team. Not everyone will like his answers but he clearly explains the reasons why he believes in any given position. He is in the process of cataloguing 50,000 years worth of genomes by sequencing the DNA found in ancient bones. The bones are destroyed in the process. He is horrified, especially as a Ashkenazi Jew, with the racism of Hitler’s Germany but explores where some pre-Nazi racial theories match current research and the difficulty of examining this with academic impunity. His heritage and profession provides a special connection and understanding to the genetic science of this homogenous group, as well as the politics of the research. The sensitivities around scientific mistreatment of Indigenous peoples, especially in the context of using the DNA collected from Native Americans is well-covered. The politics and challenges of the dissemination of his research in India is particularly interesting.
In discussion with Barry Cunliffe and others via email it is clear that I was not alone in finding aspects of Reich’s book puzzling and in need of much more research and explanation. The 90% replacement of the British population at the beginning of the Beaker period is difficult to visualise. Were these Neolithic farmers, whose ancestors had lived in Britain for at least 1,500 years, eradicated by plague many times worse than the Black Death? Or a genocide far outstripping the holocaust in such a short space of time? There is much to be worked through here. The interpretations of the movement and influence of the Yamnaya is one I also struggle to really understand. I need to read more but I suspect there is much to debate.
Ancient DNA is fundamentally changing our picture of who we are. There is much for the intellectually curious reader to glean from Reich’s book and pursue. Old archaeological problems are being solved but in the process new mysteries emerge. The once seemingly impenetrable fog of the deep past is lifting and how ancient human populations spread across the world is being made visible. It is clear that we are not always who we think we are. One important message – there are no ‘pure’ races: all modern human populations are mixtures of more ancient ones – should be writ large, for all to see.
* Most non-Africans are about 2 percent Neanderthal and slightly less than 2 percent Denisovan. Both percentages are calculated using a sophisticated analytical method that looks at parts of your DNA that you share with these hominin populations.
Other titles read during April
Bad News (Patrick Melrose #2) (1992) by Edward St. Aubyn
Sea of Poppies (2008) by Amitav Ghosh
Guilty Thing: A Life of Thomas De Quincey (2016) by Frances Wilson
The Unsung Artistry of George Orwell (2013) by Loraine Saunders
Hope Lies in the Proles: George Orwell and the Left (2018) By John Newsinger
George Orwell’s Commander in Spain: The Enigma of Georges Kopp (2013) by Marc Wildemeersch