Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past, by David Reich, Oxford University Press, 335 pp, £20, ISBN: 978-0198821250
In this fascinating book on ancient DNA, Harvard professor David Reich presents his scientific data in the field of genetics in the context of a spirited defence of the political and social implications of his research. His important book is both thought-provoking and readable and includes instructive and useful diagrams peppered throughout the text which add to the clarity of the author’s arguments. Apart from the new and exciting findings there are very interesting philosophical, ethical and academic debates surrounding this research. It also has profound implications for other disciplines such as history, linguistics, anthropology and archaeology.
Reich explores the genome, defined as the full set of genetic code each person inherits from his or her parents, as “a prism for understanding the history of our species”. The discovery that the genome is written out in twin chains of about three billion chemical building blocks that can be thought of as letters of the alphabet was made by Francis Crick, Rosalind Franklin, James Watson and Maurice Wilkins in 1953. A gene, typically around one thousand letters long, can be read by machines. The technology for what Reich refers to as “the ancient DNA revolution” was invented by Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. When Pääbo realised in 2007 that he would be able to sequence almost the entire Neanderthal genome, he assembled an international team of experts with the goal of ensuring that the analysis would do justice to the data. That is how Reich got involved and he was to play an important role in the analyses that proved the occurrence of interbreeding between Neanderthals and some modern humans. Neanderthals became the first archaic humans to be recognised by science. In The Descent of Man, published in 1871, Charles Darwin argued that humans are like other animals in that they are also the products of evolution. Reich set up his own DNA laboratory in 2013, the first in the United States focusing on whole-genome ancient human DNA. By the end of 2015 his lab at Harvard had published more than half of the world’s genome-wide ancient human DNA and by 2017 genome-wide data for more than three thousand ancient samples had been generated.
One of the interesting discoveries resulting from Reich’s studies using ancient DNA analysis is that the people who live in a particular place today almost never exclusively descend from the people who lived in the same place far in the past. He argues that present-day populations are blends of past populations, which were blends themselves and that “population mixture is central to human nature”. He notes that a person’s genealogy, gleaned from historical records, is not the same as his/her genetic inheritance and that each person has not inherited any DNA from the vast majority of his or her actual ancestors. Present-day people in Europe and India have strong genetic affinities to the “Yamnaya”, ancient steppe pastoralists, which Reich promotes as candidates for spreading Indo-European languages. The common ancestor of everyone living today lived more than one million years ago.
Reich’s mentor, Svante Pääbo, cites the search for the genetic basis for modern human behaviour as a justification for sequencing the genomes of archaic humans to establish if biological change contributed to behavioural change. For example, archaeologists have recovered artefacts dating to approximately 50,000 years ago which suggest ritual, religious or magical practices by archaic humans. These include items such as beads made of ostrich eggshells, polished stone bracelets and red ochre used as body paint. Archaeologists have also discovered representational art such as the c30,000-year-old drawings of pre-ice age animals found on the walls of Chauvet cave in France. These are interpreted as expressions of the transcendent ‑ what makes us human. Biological determinism as an explanation of human behaviour has its limitations. Biological elements determine capacity or ability, the potential of which cannot be reached without appropriate environmental context. Reich himself expects that “no intellectually elegant and emotionally satisfying molecular explanation for behavioural modernity will ever be found”. Perhaps this is because despite Darwinian ideas to the contrary we humans are inclined to think of ourselves as superior in the animal world. Mind and imagination aren’t so easily quantifiable.
A whole population history is contained within a single person, as the histories of many ancestors are recorded within that person’s genome. This makes some vulnerable populations very wary of the ancient DNA revolution. There is hostility among some Native American tribes, for example, towards genetic research in general. In 2002, the Navajo passed a Moratorium on Genetic Research, forbidding participation of Navajo tribal members in genetic studies of any kind. The document reads: “Human genome testing is strictly prohibited by the Tribe. Navajos were created by Changing Woman, therefore they know where they came from.” This traditional and imaginative origin story is probably more protective of the Navajo as a tribe and a community than a scientific genetic study, which could be used in their favour or used against them for the benefit of others. It would seem they don’t want outsiders controlling their knowledge of themselves and imprisoning them in the scientific categories of Western science. As the anthropologist Kim TallBear has pointed out: “Tribes do not like having a scientific world view politically shoved down their throat.” Of course, there is the counter-argument that modern studies of DNA variation would benefit them greatly by contributing to the understanding and treatment of disease in their populations.
Scientific endeavour, while having cultural authority in the modern world, has never been divorced from its times. For example, in the 1930s Harvard carried out anthropological studies on potential immigrants to the US in Czechoslovakia, Belgium, Norway, Sweden, Denmark, Italy, Holland, Poland, Germany, Great Britain and the Irish Free State in an effort to establish if the inhabitants of those countries were “eugenically fit” to be allowed into the United States. One of the aims of the American eugenics movement in the 1930s was to create an American eugenic presence throughout the world in an effort to address population and migration problems scientifically. Eugenics, now regarded as a variant of scientific racism, was considered to be the science of better breeding for human beings prior to World War II. Physical anthropologists in the 1930s believed there was a biological basis for human behaviour and claimed that their measurements of skulls could provide scientific evidence of proclivities for socially deviant behaviour such as drunkenness and criminality.
Many anthropologists and geneticists argue that there are no differences among human populations that are large enough to support the concept of biological race. Reich asserts that this position will not survive the onslaught of science. However, while he does not use the terminology of race he does argue that the results of the genome research reveal hard evidence of substantial differences across populations. He confirms that the classification of humans, originally made in the eighteenth century, as Caucasoids, Mongoloids, Negroids and Australoids is validated by his whole-genome research. He reckons that it is “a more powerful way to cluster present-day human populations than physical features”. However, this raises the question – could DNA clusters be used to discriminate against people in the future?
Reich also argues that “Ancient DNA should be liberating to archaeologists” as it can be used to reveal how ancient peoples related to each other and how migrations contributed to the changes evident in the archaeological record. Unfortunately, the use of human biological data in the service of history and archaeology has itself a dubious history. The rise of archaeology and history paralleled the rise of nationalism in Europe in the late nineteenth and early twentieth century. Indeed the construction of nation-states depended on these disciplines for authentication of their unique cultures and for scientific validation of their political aspirations in terms of territorial claims. In Ireland, the Harvard Archaeological Mission carried out a five-year research programme of excavations as well as physical and social anthropological studies between 1932 and 1936. They attempted to establish the origins of the Celts, and who their descendants were among the modern population. The manager of the programme was Earnest A Hooton, an ardent eugenicist who was eventually disciplined by Harvard University for his “inhuman teachings”. Eugenicists were behind the introduction of harsh immigration laws in the 1920s in America and being classified as white, Celtic and Western or Northern European was a distinct advantage to potential immigrants.
As the author acknowledges, particularly in relation to archaeology and anthropology, scientific data was interpreted in Nazi Germany to serve the regime’s interest. However, he is at pains to point out that the Nazi ideology of a ‘”pure” Indo-European-speaking Aryan race with deep roots in Germany has been proven scientifically to be false by the findings of ancient DNA research and that the results persistently show that there was repeated mixture in human history and that this discovery has demolished arguments for biologically based nationalism. He is adamant that ideologies that seek a return to a mythical purity are “flying in the face of hard science”. Reich refers, in his discussion, to the discredited theories of the German archaeologist Gustaf Kossinna, who was one of the chief architects of the political exploitation of archaeology under national socialism. Kossinna was appointed professor of German prehistory at the University of Berlin in 1902 and published Die Herkunft der Germanen (The Origin of the Germans) in 1911. Kossinna’s work used archaeology to seek to establish a historical right to territory whereby artefacts recovered from sites in countries bordering Germany, deemed to have belonged to ancient Germans, authenticated modern Germany’s claim to that territory. He became famous for correlating ethnic groups with assemblages of artefacts. The Nazis considered that only prehistorians could provide the necessary evidence of the superiority, antiquity and racial purity of the ancient Germans and when they came to power in 1933 they began to fund archaeological research in German universities. Kossinna’s theory that Germany was the centre of European civilisation and that its cultural influence spread outwards in antiquity appealed to the Nazis. Kosinna believed that the Germans had stayed in their own homeland and were not mixed with foreign blood and therefore remained racially pure and culturally superior to other Indo-European peoples.
Reich also refers to the archaeological work of one of the most eminent and influential scholars of European prehistory in the twentieth century, V Gordon Childe. Childe, like his contemporaries, was influenced by the racial ideology of the times, reflected in his book The Aryans, published in 1926. Here he described the way Aryan language and culture was carried from the cradle land to regions previously un-Aryan, ideas influenced by the work of Kossinna. Childe described the Aryans as “the tall blond stock, the European race par excellence”. He agreed with Kossinna with regard to the latter’s Scandinavian theory of Aryan origin. Later Childe was to rethink his position and rejected the association of cultures with particular races and the equation of German cultural creativity in the past with ethnic purity. But even at the time of writing The Aryans he displayed an awareness of the dangerous political implications of his ideas and warned that the word Aryan had become the watchword of dangerous factions and especially of the more brutal and blatant forms of antisemitism. He strongly disapproved of the racialist writings of contemporary eugenicists. Ideas about the purity of races were eventually to be discredited in archaeology and anthropology after World War II.
The question about the homeland of the original Indo-European languages is one that has continued to be important in European archaeology today. In 1987, the prehistorian Colin Renfrew argued in his book Archaeology and Language: The Puzzle of Indo-European Origins for the correlation of the spread of Indo-European languages with the spread of agriculture from Anatolia, beginning nine thousand years ago. His view contradicted that originally postulated in the 1950s by the archaeologist and linguist Marija Gimbutas that Indo-European languages originated in the Steppe. Her views have now been vindicated by Reich’s DNA analysis, which shows that the most important source of ancestry across northern Europe today is the “Yamnaya” who expanded in prehistory from the Steppe, north of the Black and Caspian seas, and were likely to have spread a major new group of languages throughout Europe.
Reich’s researches also show that from about 4,500 years ago dozens of ancient British DNA samples had large amounts of Steppe ancestry. He reinstates the outmoded idea in archaeology of the “Beaker Folk” (named after their distinctive pottery) migrating to Britain 4,500 years ago, bringing a new culture. The “Beaker folk” did not have the same DNA as those from an earlier period but have a similar blend of ancestries as modern-day Britons. However, he also concluded that the initial spread of the Bell Beaker culture across Europe was through the movement of ideas and not by migration. When these new cultural ideas reached Central Europe further spread of the Bell Beaker culture was accounted for by migration. DNA analysis of British and Irish skeletons from the Bronze Age, following the Beaker period, had at most around 10 per cent ancestry from the first farmers of these islands, with the other 90 per cent from people like those associated with the Bell Beaker culture in the Netherlands. Reich is aware of the pitfalls of the interdisciplinary study of archaeology, genetics and linguistics: “It is easy to get ensnared in trying to establish neat correlations between genetic dates and the archaeological record, only to have dates shift when a new genetic estimate of the rate of occurrence of new mutations comes along, causing the whole intellectual edifice to come tumbling down.”
Scientific origin stories for human beings are deemed superior because they are tested by the scientific method against a range of evidence. However, it is in the interpretation of scientific evidence, sometimes by non-scientists and in the media, where tentative results and theories can be presented as immutable facts, that the real danger lies. Scientists, in general, do not have control over who has access to their published research and how and where it might be used. The author admits that the politics of genome bloggers and journalists tend to the political right in America and discusses the example of the writings of Nicholas Wade, a New York Times journalist who published A Troublesome Inheritance: Genes, Race and Human History in 2014. Wade argues in his book that there is a genetic basis for differences across human populations and that these correspond to classic stereotypes. He also suggests that a politically correct alliance of anthropologists and geneticists had suppressed the truth about this. But even scientists themselves can have biases and prejudices, since they are human and, therefore, flawed. James Watson, the famous co-discoverer of the structure of DNA as a double helix and a Nobel laureate, was forced to retire as chancellor of Cold Spring Harbor Laboratory in New York in 2007 after making controversial comments to the Sunday Times about the genetic inferiority of Africans. He expressed the view that “our social policies are based on the fact that their intelligence is the same as ours – whereas all the testing says not really”. Cold Spring Harbor Laboratory was the base of the Eugenics Record Office between 1910 and 1939, originally founded as a department of the Carnegie Institution of Washington Station for Experimental Evolution.
Ancient DNA studies, like archaeology and anthropology in the service of the state, could potentially be used to claim deep roots in a designated territory even if there has been mixing in the deep past. The fact that they can be identified as a uniform group in DNA terms means they have unique biological markers. Information and scientific data on human beings in the recent past or in the prehistoric past is always useful politically and difference can always be used to legitimise discrimination. Reich laudably argues that: “The genome revolution provides us with a shared history that, if we pay proper attention, should give us an alternative to the evils of racism and nationalism, and make us realize that we are all entitled equally to our human heritage.” This is a noble aspiration expressed at a time of rising nationalism and re-emerging racism in America, Britain and Europe, expressed in Trumpism, Brexit and the rise of far-right politicians in Europe.
The complexities of the politics of his research aside, Reich’s Ancient DNA discoveries have far-reaching consequences for interpretation in archaeology. Not since 1949, when the American chemist Willard Libby invented radiocarbon dating, has archaeology been transformed on a global scale. Ancient DNA, according to Reich, is even more revolutionary as it is providing definitive answers to questions about whether changes in the archaeological record reflect movements of people or cultural communication. Reich aspires to create an ancient DNA atlas of humanity to rival the first maps of the globe made between the fifteenth and nineteenth centuries in terms of its contribution to human knowledge and to provide a framework for studying new archaeological sites.
The author insists that the discovery of substantial biological differences across populations should be recognised but we should “accord everyone the same freedoms and opportunities regardless of them”. While this sentiment is a politically correct one human beings, including political leaders, tend to be self-interested. When faced with power battles over territory, resources, politics and immigration, they are wont to use everything at their disposal, including scientific data, to achieve their goals. Reich reiterates that the findings from ancient DNA highlight the connections among people not previously known to be related. His study of the deep past is intrinsically interesting as it explores fundamental questions not only about our origins as human beings but also our future and what identity means in terms of our DNA. As the author asserts confidently, “there is no stopping the genome revolution”. However, the history of the study of human variation has shown that it has not always been a force for good.
MairéadCarew is an archaeologist and writer. Her most recent book is The Quest for the Irish Celt: The Harvard Archaeological Mission to Ireland, 1932-1936 (Irish Academic Press, 2018)