Our human race, Homo Sapiens, is around 200,000 years old but it was only fifty years ago that we got our first glimpse of the Earth from the moon.

Earthrise. Pic by NASA

Though this past week we have been celebrating the Apollo 11 landing of Armstrong and Aldrin, the earlier Apollo 8 mission was the first to reach lunar orbit. Its commander, Jim Lovell, recalled the experience:

“I could go to the window and put up my thumb and I could completely hide the Earth behind my thumb. You have to think about that. Over 5 billion people. Everything I ever knew I could hide behind my thumb. […] The earth is a mere speck in our milky way galaxy and it’s lost to oblivion in the universe. It starts to make you think [about] your position in the whole universe.”

Twice Lovell mentions being made to think. And what he thinks about is his position. The shift in perspective that comes from seeing the Earth from far away, isolated in the blackness of space, is so common among astronauts that it has a name: the Overview effect. As Carl Sagan observed: “You spend even a little time contemplating the Earth from orbit and the most deeply ingrained nationalisms begin to erode. They seem the squabbles of mites on a plum.”

Back on Earth, the unity of humanity so evident from space is not so apparent. And it is not just the splintering forces of nationalism that are at play. Ralph Abernathy, the American black civil rights activist who succeeded Martin Luther King, was also moved by the moon landing to think about position, though his concerns were rooted in the experience of difference and discrimination. “We may go on from this day to Mars and to Jupiter and even to the heavens beyond,” he said, “but as long as racism, poverty and hunger and war prevail on the Earth we as a civilized nation have failed.”

Perspective matters because we are such visual creatures – seeing is believing. But just as often, belief shapes what we see and what we look for, even in the supposedly exacting and objective processes of science. This the central theme of Angela Saini’s new book, Superior: The Return of Race Science. In it Saini tackles the question of why we are still plagued by ideas of race and racism. Part of the answer lies in the terrible hierarchies of belonging that are grounded in ignorance of history and biology, and sustained by the politics of nationalism and nativism. But Saini’s particular goal is to excavate the deep and tangled roots that racism has thrust into science. In Superior she does so rigorously and unflinchingly, journeying across genetics and the histories of humanity and science, and meeting the eye of scientists with very divergent views on the biology of race. She returns home with a compelling and troubling tale, one given a fresh urgency by the reawakening of racism in our politics, whether mediated by President Trump’s toxic Twitter feed or the blokeish xenophobia of populists like Boris Johnson and Nigel Farage.

Saini, who was born in London to Indian parents, is open about the fact that writing the book has also been a personal odyssey and this, combined with her characteristically forensic approach to research, is the source of much of its power. Superior obliges you to look afresh at science – and racism – from a perspective that includes people who have more often been its subjects than its authors.

Superior traces how the hierarchical ideas of race that emerged from colonialist Europe were absorbed and legitimised by the categorising impulses of biology, and follows their harnessing by the social and political forces that drove eugenics – the bitter offspring of the union of Darwinian evolution with Mendelian genetics – into the arms of the Nazis. In the immediate aftermath of World War Two, actively racist scientists largely disappeared from view while the rest of the scientific community tried to extract the issue of race from the study of human beings. UNESCO’s statement in 1950 on race declared, “Scientists have reached general agreement in recognising that mankind is one: that all men belong to the same species, Homo Sapiens.”

This was far from sufficient for settling the matter. For one thing, a small group of scientists has cleaved to the view that economic and behavioural differences between nations and ‘races’ have their origins in genetics. Funded in part by organisations like the Pioneer Fund, which has been described as “racist” and “white supremacist”, they have sought to cloak their research in academic respectability by running scholarly journals such as Mankind Quarterly. It remains a fringe publication shunned by the scientific mainstream, but its continued existence is a testament to the tenacity of the political forces that keep alive the scientific racism that serves in turn to sustain the rhetoric of division. One of the most chilling quotations in Saini’s book is from far-right commentator, Milo Yiannopoulos: “behind every racist joke is a scientific fact.”

More subtle and more insidious are the struggles of mainstream genetics to disentangle itself from racialist thinking and it is here that Superior is at its knottiest and most interesting.

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The gift of 21^st Century genetics, which has hugely accelerated the rate at which we can read the DNA sequence of entire genomes, has been to disclose that beneath our superficial differences of skin colour, physiognomy and body-shape we are 99.9% genetically identical to one another. Of course, it is natural to think about the impact of the 0.1% that differentiates us – difference is what makes each of us unique. But research on differences often focuses on sub-populations – sometimes with good intentions, such as understanding probabilities of disease susceptibility – and Saini explores how in the long historical shadow of racialist thinking such work can easily become politically charged, even in the hands of avowedly anti-racist scientists. A common view that she encounters is that science should just be allowed to get on with asking questions and the data should be left to speak for themselves. But she has some hard questions of her own about that perspective.

The geneticist Luigi Luca Cavalli-Sforza, who led the Human Genome Diversity Project to probe genetic differences between indigenous populations across the world and track the history of human migration, ran into difficulties because of insensitivities to the history and culture of the peoples being studied. He also tripped up in his use of language. Cavalli-Sforza’s use of words such as ‘hybrid’ or ‘isolate’, that he supposed to be scientifically neutral, betrayed instead a mindset that was too little aware of the impacts of racism, or of the scope for racist misinterpretations of his work. As Saini points out, the solution here isn’t just about insisting on greater care with terminology, “it is about fundamentally rewriting the way we think about human difference, to resist the urge to group people at all.” For some, such a contention flies in the face of common sense – we can see that people are different. But Saini is working with the evidence – 21^st Century genetics has repeatedly confirmed the counter-intuitive finding that there is much more variation between the individuals of a population with a particular geographic ancestry than between individuals from different populations – and her view is shared by many researchers.

The faces of people who are 99.9% genetically identical to one another. Source: Sue Clark; published under a CC-BY licence.

In certain quarters, one of the strongest urges to group people is when thinking about race and intelligence, most often evaluated as IQ. Although there are measurable differences in the average IQ between nations and between groups – for example white and black Americans – the question of whether these have any genetic basis remains contentious. The arguments are slippery, and seductive to some. There is no question that human intelligence, an emergent property of brain development and activity, is rooted in our genes but there is fierce debate about how much of the variation of IQ is genetic as opposed to arising from the impacts on individuals of familial, societal and economic factors that shape their lives.

The key to understanding this thorny topic is to appreciate that while simple traits (or phenotypes), such as skin colour or susceptibility to diseases like cystic fibrosis, have genetic signatures written in just one or a small number of genes that clearly account for how they arise, this does not hold for complex traits like intelligence. The genetic basis of intelligence lies in thousands of genes, each making a minuscule contribution to the phenotype, scattered across the genome. The difference between simple and complex traits is not just one of scale and this has important consequences for how we understand the heritability of intelligence.

For example, it makes it formidably difficult to understand how intelligence works, since it emerges from the outputs and interactions of thousands of genes. That doesn’t stop some people from trying. One of the best-known researchers in area, Robert Plomin, uses a technique known as genome-wide polygenic scoring (GPS) to examine how the totality of DNA sequence variations at thousands of different places (or loci) in the genome correlates with measures of the IQ or educational attainment. Using this approach with cohorts of up to a million people, he tells Saini, he has shown that our knowledge of DNA can now explain around 10% of the variation in human intelligence.

It sounds impressive, and the work to analyse such huge volumes of data is no mean achievement, but the use of the word ‘explain’ in this context is problematic. For one thing, what we have here is correlation, not causation. For another, the predictive capacity of the GPS approach at the level of the individual is weak; despite all the data, the correlations are very imprecise. However, Plomin is undaunted. With more work, he claims polygenic scoring will soon be able to account a much higher fraction of the variation in intelligence. Elsewhere he has written, “we see IQ GPS as a system to triangulate on the genetics of intelligence from all domains of the life sciences.” Plomin’s use of the GPS is calculated to bring to mind the better-known acronym for satellite navigation (Global Positioning System) is calculated and he comes across as a modern-day Newton, convinced that once all the measurements are made, the orbital paths of genetic destiny can be plotted and predicted.

Others see things very differently, and have been sharply critical of Plomin’s deterministic perspective. He has no mechanism to explain how polygenic scores derived from thousands of genes are linked to intelligence and, according psychologist Eric Turkheimer, no prospect of finding one. Genes are not so directive of outcomes, particularly when operating and interacting in legions and giving rise to capacities that are shaped by environment and experience. Rather than endless polygenic scoring, Turkheimer looks forward to “a behaviour genetics that embraces human complexity instead of trying to reduce it to deterministic processes.”

The different philosophies of Turkheimer and Plomin might be just another academic dispute but when they spill over into public policy debates, as arguments over the genetics of intelligence have done, the stakes are raised. This shouldn’t come as a surprise but to me it is one of Superior’s most powerful lessons.

The stakes rise higher still when the question of race crops up and in this context Saini’s encounter with the leading Harvard geneticist David Reich is one of the most revealing of the book. Reich has grappled publicly with the vexed question of whether the study of human genetic diversity risks opening doors for racism – and been openly critical of the groundless racism of views espoused by DNA pioneer James Watson. He stoutly defends the value of studying human variation, not least because of the insights it might provide into group differences in susceptibility to certain diseases which could help to guide diagnosis and treatment (the complexities of which Saini explores elsewhere in the book). But he goes further, telling Saini “There are real ancestry differences across populations that correlate to the social constructions we have. We have to deal with that.”

Saini accepts science’s freedom to pursue differences in our ancestry (or more precisely, our ancestries), but the key question for her is how that is to be done responsibly. As with Cavalli-Sforza, the difficulty with Reich’s approach is that it is too open to mis-use. His assertion in a New York Times article last year that “since all traits influenced by genetics are expected to differ across populations (because the frequencies of genetic variations are rarely exactly the same across populations), the genetic influences on behaviour and cognition will differ across populations, too” was seized on by ‘race realists’ who favour the sub-division of the human species. Reich’s view has been challenged by other scientists. Mark Thomas, a geneticist at University College London tells Saini, “Most categories are nonsense, though some may be useful. ‘Race’ is useless, pernicious nonsense.” A 2007 analysis tackles Reich’s argument head-on and finds it wanting. Its conclusions are worth quoting at length:

“The fact that, given enough genetic data, individuals can be correctly assigned to their populations of origin is compatible with the observation that most human genetic variation is found within populations, not between them. It is also compatible with our finding that, even when the most distinct populations are considered and hundreds of loci are used, individuals are frequently more similar to members of other populations than to members of their own population. Thus, caution should be used when using geographic or genetic ancestry to make inferences about individual phenotypes.”

Superior is beautifully and passionately written, and blazes with insight and humanity. Saini can have few illusions that her book will be the last word on the subject of science and race. Research into human genetic diversity will go on and has important and proper questions to investigate even if its findings will inevitably be drawn into public debates that, not least on social media, remain intensely fractious. But in Superior Saini offers a calm and carefully constructed overview, a perspective to empty out racist notions that superiority and inferiority must somehow have biological foundations. They do not, in any meaningful or demonstrable sense. More importantly perhaps, Saini has peered far beyond the surface to show how deeply science is submerged in the values of the societies in which it operates and sounds a clarion call to scientists, and indeed to all of us, to be alive to history and politics in the way that the victims of racism have always had to be.

My thanks to writer Alom Shaha and neuroscientist Kevin Mitchell for critical comments on an earlier version of this blogpost. For more on the subtleties and complexities of the interactions between genes and intelligence, listen to Kevin on the Beagle Has Landed podcast.

Edited with additional content by the author on July 25th.

Stephen Curry is a Professor of Structural Biology at Imperial College, London. His work revolves around studying the three-dimensional structures from biological molecules in atomic detail, using X-rays and crystals. He was a key member of the grassroots Science is Vital campaign which worked on protecting scientific research funding in the UK. He previously was a regular contributor for The Guardian’s science blog network.

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