The Invisible History of the Human Race

by Christine Kenneally

  Fernandez and Fogli controlled for the effects of the husband’s and wife’s education, the education of their parents, the income of the husband, and the geography of markets. Even taking into consideration all these factors, it looked like the attitudes of the Old World still shaped the choices of women born in the new.

  The researchers also asked if the amount that a woman worked and the number of her children were more powerfully shaped by her own culture or her husband’s. Apparently, when a wife’s and husband’s parents’ cultures of origin are different, the husband’s parents’ culture of origin was the more significant factor. It’s unclear why this would be so, but as Fernandez and Fogli observe, the choice of marriage partner itself is hardly random.

  It is possible that the interaction between a family and a small community makes the family’s force even more powerful, suggest Fernandez and Fogli. When there is no clear separation between the people at home and the people in the neighborhood schools and churches and other institutions, the researchers found that the power of a family appeared to be greatly enhanced. The parents’-country-of-origin effect on women was magnified when the U.S. women were raised in communities surrounded by many other families from their parents’ ethnic group. The higher the percentage of the parents’ ethnic group in the neighborhood, the more likely it was that the modern women made choices that were influenced by the old ways. Even though they were isolated from the institutions of the Old World, they were still surrounded by people from that world. The groups kept the old beliefs alive and passed them on.

  • • •

  No study has found a single universal principle that dictates how beliefs and attitudes are reproduced down the generations. One study found that, like the second-generation immigrant women of the 1970s United States, Irish Americans in the 1910s had fewer children than their peers in Ireland but still significantly more than their peers in the States. By contrast, the childbearing patterns of German immigrants to the United States at the time showed no connection whatsoever with the culture of childbearing back in the old country.

  Some cultures seem to perpetuate a community closeness that in turn fosters a perpetuation of values. Immigrants from Mexico, Italy, and Japan are more likely to cluster together in new neighborhoods and presumably to maintain the historical beliefs that shaped them. The Turkish, French, and Lebanese, by contrast, are less likely to live in a neighborhood with many people of the same ethnicity.

  The way a trait is passed down in a culture may also depend on the trait itself. Trust affects economies all over the world, but in Italy, for example, it appears to have been shaped by different forces than in Africa. Guido Tabellini examined trust, respect for others, and “confidence in the link between individual effort and economic success” in economies in southern and northern Italy by comparing answers to questions like “[Would] you say that most people can’t be trusted or that you can’t be too careful in dealing with people?” Even though all the regions he examined had effectively the same contemporary level of literacy and the same quality of institutions, some of them had been less literate and had more institutional corruption in the past. Tabellini found that these latter regions had less trust, respect, and confidence today, as well as poorer economies.

  • • •

  As Nunn was beginning his research, his field was undergoing something of a revolution. A group of economists had begun to explore the way that history could influence an economy. Obviously, an economy may be affected by such immediate factors as the destruction of important institutions, the death of key figures, the failure of crops, and the spread of disease, and the more recent such an event was (such as the terrorist attacks on America on September 11, 2001), the easier it was to assess its economic impact. But now economists were setting out to try to measure the impact of distant historical events through time. They began to talk about horizontal transmission, the things that are learned from one’s peers and society, and contrast it with vertical transmission, meaning, essentially, what gets passed down. The idea inspired an enormous amount of work on the impact of colonialism, especially the way that institutions like banks, governments, and the legal system were shaped by colonialism in different countries and the way that they in turn later affected their countries’ economies. It was the first time that economists made an evidence-based case that history mattered. Their work was particularly fruitful because it wasn’t based just on this general notion but also provided a way to connect specific outcomes to particular events.

  But even though the idea that history could be measured was being taken seriously, most of the work focused on the impact of social institutions. Asking how hate or fear might affect the well-being of an economy was still considered unscientific. Partly this was a reflection of the lack of access to data that revealed people’s beliefs and the difficulty of defining precisely what culture is. This is now changing as more information about beliefs and attitudes becomes available, as large amounts of data from the past become easier to handle, and as researchers come up with innovative ways to interpret it. But partly—and ironically—researchers did not examine the economic consequences of elements like trust and hate and fear because of a belief that these things didn’t matter beyond the lives and lifetimes of individuals.

  Yet as Fernandez and Fogli point out, markets have a fundamental relationship with beliefs. A culture’s belief about the permissibility of selling another human being as chattel will affect whether it has a slave trade and how widely it operates. The belief that it’s good for women to work outside the home will affect the size of the workforce. Since their research was published, Wantchekon said, the dismissal of culture as a factor in studying economics has changed: “‘Culture’ was no longer a dirty word.”

  What lessons might we take from these extraordinary connections between ancestral experience and modern attitudes? First, let’s be clear: No one is suggesting that the lives of our ancestors may be examined like a fortune-teller’s deck of cards and our own fate foretold from them. Correlation is not causation. Our forebears may simply have nothing to do with our psychological makeup at all. But we may in some respects be profoundly shaped by what happened to those who came before us, and sometimes the past matters, whether we are actually aware of it or not.

  It strikes me that being cognizant of the grand historical arcs our families have lived through could also enable us to better see what qualities we have freely chosen for ourselves and what we have unthinkingly inherited from our great- and many-times-great-grandparents who lived in a different time and possibly wanted quite different things from their lives. If someone discovers that one or many of his ancestors were immigrants or exposed to the slave trade or a plague or famine, he may find that that knowledge illuminates some aspect of his life now, whether it’s an idiosyncratic word his father uses, his own reluctance to travel, the number of his own children, or his family’s penchant for not talking about family.

  Historians, of course, have been telling us for hundreds of years that history matters and that we as a society cannot be free from the past if we don’t learn from it. Now the fascinating correlations found in this economic research suggest that distant historical events may influence the character of a modern family and that the choices of families can illuminate big history. Recall Ralph Waldo Emerson’s cry, “Why should not we also enjoy an original relation to the universe?” Maybe we can, but it will surely help if we can identify what was passed down to us and what we have freely chosen for ourselves.

  Obviously, the circumstances of our lives shape us too. Education has a huge impact, as do job opportunities. Personal income can, of course, change everything. The influence of particular individuals, whether teachers, mentors, or spouses, also matters.

  All these factors may interact with one another as well. It’s complicated and recursive. We are shaped by events, and then we shape people who initiate other events. We are shaped directly by people, an
d we shape others accordingly. Documents and ideas and feelings that are passed down may tell us about this; DNA is a record, and it is passed down too. What can it tell us?

  Chapter 8

  The Small Grains of History

  You may not be able to leave your children a great inheritance, but day by day, you may be weaving coats for them which they will wear for all eternity.

  —Theodore L. Cuyler

  Westray is an hour’s ferry ride from Mainland through the dark black water of the North Sea. The island of Mainland is itself an hour’s trip from the coast of Britain, which is, of course, itself a relatively small island off the western coast of Europe. Of the tens of millions of people who were either born on or swept into the British Isles over the last ten thousand years, there are six hundred people left in Westray, and only ten thousand in the Orkney island group, of which it is a part.

  The road from the ferry terminal to Pierowall, Westray’s biggest town, rolls up and down the length of the island, traveling through pale green fields and sections of craggy rock, at points opening out to reveal vistas of the sea at either side. Along the eastern cliffs puffins are drawn with such precise lines they look prim against the wildness; on the beach fat selkies loll. Their velvet hides and anime eyes almost distract from the spectacle they create when they flop toward the sea—a reminder that evolution does not make überathletes for every niche but only does enough to get by. Even in May the Arctic wind has an icy hand.

  Legend has it that a Spanish galleon sank off Westray’s coast in 1588. Sailors swam to the islands, and those who weren’t dashed on the rocky spires were welcomed. But on Westray’s neighbor, Papa Westray, it soon became clear there wasn’t enough food for the winter for everyone, so the locals pushed the poor sailors over the cliffs until there were none left.

  On Westray, though, the ones who made it safely to shore proved helpful enough to keep. They married local girls, and the accidental immigrants and their descendants were thereafter known as the Dons. They were renowned as extroverted performers and great sailors, yet after the first generation the Dons kept to themselves. Romance with the locals was forbidden, and one young Don who broke the rule, so the story goes, was murdered by his cousins. The Dons would have made a striking contrast to the pale, light-eyed locals. For many years people on the island who had dark hair or olive skin were said to be descendants of these sailors.

  It is a romantic origin story, and it’s not implausible, but in the absence of solid records it’s hard to determine if it is real. After all, this is the same island chain in which local lore had it that throwing a cat over your house in a particular direction would ensure a good wind for your sails. Who knows which of the old tales were true and which were concocted to explain an anomaly—like the birth of a dark-haired child to blond parents, who told their neighbors that young Angus’s Spanish ancestry was showing?

  The day I caught the ferry from Mainland and drove to Pierowall’s tranquil half-circle bay, I saw a lot of lovely blue eyes but no dark-haired beauties. In the town archives, outside which lay the massive skeleton of a sperm whale, I read about the Dons and leafed through old photos. Here and there were pictures of olive-skinned youths, looking reasonably Spanish. But the records didn’t reveal much about who they actually were or even if they were native to the island.

  Still, behind their eyes, beneath their skin, below the membranes of their cells there is something in the DNA of Westrayans that marks them and no one else. The origin of that distinction is not yet clear, but whatever it was, the scientific team that detected it in 2012 discovered that even the Orkney Mainlanders don’t have it. Is it a legacy of the Dons or something much older and weirder?

  It’s not just the Westrayans who are different from everyone else. If you examine all the longtime residents of all the Orkney Islands together, they too have something inside their cells that distinguishes them from everyone else in Britain. Throughout the British Isles, in fact, clusters of people carry distinctive traces of ancient events within them. Celtic kingdoms, barbarian invasions, Norse raids from more than a thousand years ago—traces of these distant, almost mythical moments in time are written in the bodies of the good and ordinary people of Devon, Anglesey, Westray, and many other places.

  These traces were discovered by an Oxford team that has found a way to read the book of history in human DNA to a level of detail that is completely unprecedented. Indeed, it is the closest thing we have to a time machine. Which is not only to say that it’s merely our best shot at traveling through time; in fact, it’s quite close to it.

  • • •

  In 1980 Peter Donnelly, an ex-Queenslander who attended Oxford as a Rhodes scholar, was deemed so bright that at twenty-nine he was appointed the youngest full professor in England (and, it’s reputed, the youngest full professor in that country in more than a century). Donnelly is now director of the Wellcome Trust Centre for Human Genetics and a professor of statistical science at St. Anne’s College, Oxford. Refuting all the stereotypes of outsize genius, he is towering and deep voiced, and if life had led him that way, he could have made an unusually tall but dignified magistrate. Although he trained as a statistician, his work increasingly took him into genetics, and over a period of about ten years he changed from a mathematician who dabbled in genetics to one of the world’s leading geneticists.

  I met with Donnelly and his colleague Stephen Leslie at one of the genetic world’s most pleasantly located meetings, by the beach in Lorne, Australia, some nine thousand miles from Westray. As the afternoon tide hit its low point and turned around again, Donnelly and Leslie walked me though a brief history of genetic research in the twenty-first century, which has so far featured one particularly huge upheaval.

  While genes were discovered around the beginning of the twentieth century, it wasn’t until 1953 that the double-helix structure of DNA—the stuff that genes are made of—was discovered by James Watson, Francis Crick, and Rosalind Franklin. Almost five decades later a human genome was sequenced for the first time. Despite this enormous and expensive step, the project of linking specific genes to traits or diseases has until recently proceeded painstakingly, one gene at a time. Researchers would pick “their favorite gene,” Donnelly said, and investigate only that. “It wasn’t based on the idea that there was only one gene involved in the condition,” Donnelly explained; rather, it was simply too expensive to look at anything else.

  The problem with candidate gene studies, however, was that a promising result—say, the discovery that a majority of patients with a particular disease appear to share a marker that a group of healthy people do not—might not actually have anything to do with the actual disease. “Now we know that people in Scotland will have genetic variants that differ from people in, say, Tuscany,” Leslie explained. “It could be just by chance or it could be by natural selection, but there will be differences between Scots and Tuscans.” The danger with candidate gene studies, he said, “was that you thought you were seeing something that was associated with having a particular trait, but actually what you were seeing was something associated with being Scottish or Tuscan.” (The other problem with candidate gene studies is that “almost all of those results turned out to be wrong,” Donnelly said. “One of the lessons of that era is how bad experts were at picking candidates.”)

  Around 2007 not only did it become possible to investigate many places in the genome simultaneously, but also the cost of doing so quickly dropped. In a matter of years candidate gene studies were replaced by genomewide association studies. Researchers now had an eagle’s-eye view of an individual’s entire genome, and they were able to compare tens of thousands of sites in the genomes of tens of thousands of people to identify meaningful correlations with a trait or disease or with the history of a population.

  Scientists have known since before they had the technology to measure them that regular genetic differences—what geneticists call “population struc
ture”—probably existed. “For as long as we have measured traits in human populations, we’ve known that the distribution of those traits vary in different parts of the world, depending on which population is measured,” said Donnelly. “For a long time we only knew about a few markers, like blood groups, which we have measured since the 1930s.”

  Indeed, blood is the classic example: The A blood group is found mostly in Europe, while there’s considerably less type A in Asia. The B blood group is more common in Africa than in Europe. The Rh factor, named for the rhesus macaques used to investigate the trait, refers to the presence or absence of a set of red-blood-cell antigens, and it differs too among populations: Rh-negative blood occurs far more often in Europe than in Asia. Even within particular European populations there are differences in blood groups. The Irish Blood Transfusion Service, for example, gets more O-negative when it collects blood in the western part of Ireland than in the east.

  Some biological differences between groups may have little to do with how individuals actually live their lives, yet they may still be potent with meaning. They may reveal how long the groups have been separate, how long they have lived in one area, whom they mixed with in the past, and whether their bodies have adapted to local conditions. Combined with historical records, artifacts, or information about the biology of other groups, they may tell us when population differences arose and why they happened. Essentially, one can use the living tissue of human beings to work out what the lives of their ancestors were like up to hundreds and thousands of years ago. It’s like William Blake’s poem about seeing the world in a grain of sand, except that instead of a metaphor it’s real: What you will see is the history of the world in a handful of human cells.