1. Context

2. Book
    Publication  Summary 

3. Reception
    Favourable  Unfavourable 

4. References

5. Sources

6. External links

Who We Are and How We Got Here is a 2018 book on the contribution of genome-wide ancient DNA research to human population genetics by the geneticist David Reich. He describes discoveries made by his group and others, based on analysis and comparison of ancient and modern DNA from human populations around the world. Central to these is the finding that almost all human populations are mixtures resulting from repeated population migrations and mixtures.

Scientists and critics have praised the book for the pioneering work that it describes. It has also been criticised for its writing style^[1] and its handling of race,^[2] though other reviewers observe that nothing it says should give racists any comfort.^[3]

Context

Book

Publication

Who We Are and How We Got Here was published by Oxford University Press in 2018, {{ISBN|978-0-19-882125-0}}. It is credited to David Reich alone, but he explains in the Acknowledgements that the book grew from a detailed collaboration with his wife, Eugenie Reich.

The book is illustrated with monochrome maps, diagrams, and timelines. There are no photographs.

Summary

Since 2010, population geneticists have been able to sequence ancient human DNA, recovering complete genomes,^[3] in contrast to earlier approaches which relied on the far more abundant (and hence more easily recovered) mitochondrial DNA, which is present in many copies in each cell, and transmitted only via the maternal line. That early work gave the "exciting" result that all modern humans are related to "Mitochondrial Eve", a woman who lived in Africa only about 160,000 years ago.^[7]{{sfn|Reich|2018|pp=4–5}}

The whole genome recovery technique, using the especially hard bone from the inner ear of ancient skeletons -- along with the genomes of modern people from different parts of the world, including especially some isolated populations -- has made it possible to reconstruct prehistoric migrations and mixing of populations in the past 5,000 years, and to make reliable inferences about mixtures from much further back in time.^[3] The new knowledge from genomics has overthrown many old assumptions about human origins.^[3]

Much of the work has focussed on Western Eurasia, where in 1786 Sir William Jones discovered that Sanskrit and ancient Greek were related languages. Linguists came to recognise the Indo-European family of languages, spanning Germanic, Celtic, Italic, Iranian and northern Indian languages, but without explaining how these came to be. Reich showed that modern populations in Europe and north India derive from mixing of native populations with Yamnaya people from the steppes north of the Black Sea and the Caspian Sea some 5,000 years ago, in separate migrations to the west and the east.^[3][2] Corded ware culture described by archaeology corresponds to a stage in the westward migration.^[3]

Similar migrations and population mixtures characterise human prehistory on all continents.^[3] Reich shows that people in Japan and Korea share some 80% of their DNA, implying migration; Polynesians migrated relatively recently, in just the past few thousand years, from the region of Taiwan. The evidence can upset long-held beliefs: Native American skeletons from 10,000 years ago do not appear to be related to the tribes living in those regions today who have been asking for the ancient bones to be returned to them for burial.^[7]

The Neanderthals are extinct, but part of their genome survives: All present-day non-Africans have at least 2% of Neanderthal ancestry. Reich explains that somewhere between 100,000 and 50,000 years ago, modern humans mated with Neanderthals, and their descendants carried those genes all over the world. An ancient skeleton from Romania had up to 9% Neanderthal DNA, so natural selection has been removing Neanderthal genes since those matings.^[7]

Reception

Scientists and critics have praised the book for the pioneering work that it describes. It has also been criticised for its writing style^[3] and its handling of race,^[2] though other reviewers observe that nothing it says should give racists any comfort.^[3]

Favourable

Peter Forbes, in The Guardian, calls the book "thrilling in its clarity and its scope."^[5] In Forbes's view, Reich handles racist abuses of human origin stories, such as Nazi ideology, "commendably". Forbes writes that Reich explains how ancient DNA teaches a single general lesson, that the human population of any particular place has repeatedly changed since the last ice age; any supposed "mystical, longstanding" link between some people and a place, based on some kind of racial purity, is in Reich's words "flying in the face of hard science".^[5]

Clive Cookson, in the Financial Times, writes that one of the first and most surprising impacts of genomics is in human prehistory, and Reich is the first leading practitioner to write a popular book about this. Cookson calls the book^[6]

Cookson notes that Reich dismisses worries that DNA evidence of differences between populations is "racism in genetic clothing",^[6] and that on the contrary, the "unsuspected degree of mixing"^[6] in every part of human history makes old ideas of racial purity "absurd".^[6]

The archaeologist and geneticist Turi King, in Nature, writes that Reich's laboratory "has developed some of the most sophisticated statistical and bioinformatics techniques available. Using computers, they painstakingly reconstruct genomic information from fragments of DNA from ancient individuals. They then drill down in search of a new understanding of human history." King notes that Reich's group helped to show that "Neanderthals interbred with the ancestors of all modern humans descended from Europeans, Asians and other non-Africans." Their work is showing the "tremendous degree to which populations globally are blended, repeatedly, over generations." King notes, too, that Reich reflects on the dangers of misinterpretation by racists, who "pick and choose results", or others who opt to "sweep [genetic] differences under the carpet". But, King argues, echoing Reich, we do need "a non-loaded way to talk about genetic diversity and similarities in populations", and Reich has begun to do that.^[7]

The economist Tyler Cowen calls the book "truly excellent, readable and informative". Cowen insists it is "a science book, not a 'race book'", stating that although it has engendered "some public controversy", he is confident that no attentive reader could feel "affirmed in racist beliefs".^[8]

The educator Darcy Moore of the University of Wollongong calls the book "highly recommended" but finds some of Reich's conclusions "puzzling and in need of much more research and explanation." A case in point is Reich's statement that the population of Britain was 90% replaced by the incoming Indo-Europeans at the start of the Beaker period. Moore comments that he and the archaeologist Barry Cunliffe (who along with the archaeologist Colin Renfrew praises the book on its back cover) agreed in an email discussion that such a radical change was difficult to understand.^[9]

Gerhard Meisenberg, in Mankind Quarterly, writes that molecular genetics is a science only 25 years old, but growing "exponentially", noting Reich's comment that it takes longer to publish a paper than for the field's data to double in size. He recommends reading the book soon before the field's progress renders it obsolete. He is interested in the obstacles to research, including rapid decay of DNA in the tropics, bureaucratic export restrictions, and nationalism; and in the "disruptive" nature of science, its uneven style of progress as old theories (like the idea that modern humans arose in several regions, popular until the early 1990s) are abandoned. He notes Reich's "restraint" in saying little about how human diversity arose: scientists simply do not yet know, but natural selection acted on many genes and phenotypes: it was not a matter of creating "behavioral modernity" with any large mutation.^[10]

Unfavourable

An open letter "by a group of 67 scientists and researchers" including anthropologists, sociologists, historians, and others takes Reich to task for his book, under the heading "How Not To Talk About Race And Genetics".^[11]

The group welcomes Reich's challenge to the "misrepresentations about race and genetics"^[11] made by the science writer Nicholas Wade and the molecular biologist James Watson, but warns that his skill with genomics "should not be confused with a mastery of the cultural, political, and biological meanings of human groups."^[11] The group argues that Reich's understanding of "race" [their quotation marks] "is seriously flawed",^[11] and that "biological traits" like sickle cell anaemia have "nothing to do with"^[11] race, but are simply found in parts of the world, in this case where malaria is common. The same goes, the group argues, for other distinctions that Reich makes in the book.^[11]

The paleogenomics researcher Maria C. Avila Arcos reviews the book in Science magazine, arguing that "troubling traces of biocolonialism undermine an otherwise eloquent synthesis of ancient genome research."^[12] She calls Reich's account graceful, combining his personal opinions with "hard science"^[12] (Reich's phrase). She accepts that the book is "scientifically solid and comprehensive",^[12] but argues that it "raises some concerns",^[12] since in her view Reich overlooks the conflict of interest between the needs of researchers to gather ancient human DNA specimens and the rights of the often marginalised populations that descend from those ancestors.^[12]

The anthropologist John Hawks, writing in the Wall Street Journal, observes that Reich was surprised that the "concordance of near-mythological history with genetic fact"^[14] in the migrations in India were "a potential political bombshell";^[14] he notes that Reich avoided it by not talking about "Indo-European invaders at all",^[14] writing only that "No group in India can claim genetic purity".^[14] In Hawks's view, Reich "seems a contradiction: Rising to the pinnacle of human genetics, he nonetheless exhibits incredible naiveté"^[14] in affairs such as when German scientists withdrew from a paper that seemed to them "uncomfortably close to pre-Nazi racial theories",^[14] or when Native American specimen donors wished to limit the use of their DNA. Hawks argues that science needs to help people to see the humanity of the dead ancestors, and finds Reich's approach potentially dehumanizing.^[14]

References

Sources

• {{cite book |last=Reich |first=David |authorlink=David Reich (geneticist) |title=Who We Are and How We Got Here |publisher=Oxford University Press |year=2018 |isbn=978-0-19-882125-0 |ref=harv}}

External links

• David Reich on Radio Boston
• [https://www.bbc.co.uk/news/science-environment-43701630 Reich interview on BBC]

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