A Brief History of Everyone Who Ever Lived: The Human Story Retold Through Our Genes

by Adam Rutherford

pollarded,

The time we have been recording history is an evolutionary wing-flap equivalent to a single character, the width of this period<.> And how sparse that history is! Documents vanish, dissolve, decompose. They are washed away by the weather, or consumed by insects and bacteria, or destroyed, hidden, obfuscated, or revised. That is before we address the subjectivity of the historical record. We can’t agree definitively on what happened in the last decade. Newspapers record stories with biases firmly in place. Cameras record images curated by people and only see what passes through the lens, frequently without context. Humans themselves are terribly unreliable witnesses to objective reality. We fumble.

All human genomes host the same genes, but they all may be slightly different, which accounts for the fact that we are all incredibly similar, and utterly unique.

There is no more controversial subject in all of science than race—people are different from each other, and the weight of those differences is something that has caused some of the deepest divisions and cruelest, bloodiest acts in history. As we will see, modern genetics has shown how we continue to get the whole concept of race so spectacularly wrong.

Alas, we are no more or less evolved than any creature. Uniqueness is terribly overrated. We’re only as unique as every other species, each uniquely evolved to extract the best possible hope for our genes to be passed on into infinity given the present unique circumstances.

Nowadays, only the willfully ignorant dismiss the truth that we evolved from earlier ancestors.

provenance

We anatomically modern humans are generally thought to have evolved primarily in eastern Africa around 200,000 years ago, and emerged out of Africa in our own exodus sometime in the last 100,000 years.

inveigled

A popular exam question for undergraduates studying paleoanthropology is “Did Neanderthals speak?” The correct answer, to be spread over 3,000 words of supporting anatomical evidence please, is that Neanderthals were capable of speech, very probably. The structure of their throats is not dissimilar to our own and, in particular, the discovery of a hyoid bone in the Kebara Cave in Israel in 1989 indicated that their capability of speech must have been similar to our own.

Neanderthals probably had the capacity for speech, like us.

There is a gene, much studied and much lauded, that is inextricably bound to speech. It’s called FOXP2, and although we don’t really have a great understanding of what it does in the body, it is clear that it is essential for the type of verbal communication and dexterity that we find so trivially easy,

There’s only two changes

peloton

eremite

Around a million years ago, somewhere in Africa, a group of humans lived who were to be separated into us, the Neanderthals, and the Denisovans.

This is an absence of evidence, which we scientists like to remind people is not the same as evidence of absence.

Pope John Paul II pontificated, as popes do, in 1996 that evolution was more “than just a theory,” which while being a generous bridging gesture between the magisteria of science and religion, misunderstands that theories in science, unlike in the vernacular, are the top of the intellectual pile, the zenith of descriptions of the true nature of nature.

Theories are the best we’ve got.

doyen

The seven billion of us alive today are, according to all the evidence available to us, the last remaining group of human great apes from a set of at least four that existed 50,000 years ago.

For our purposes, if we are to look at the evolution that led to where we are now, instead of the nice neat tree, I think it could reasonably be described as one big, million-year clusterfuck.

The “Paleo Diet” is a popular fad that eschews processed foods and carbohydrates in favor of the only foods imagined to be available to the hunter-gatherers of the Paleolithic: no dairy or processed grains, no lentils, beans, peas, or other human-designed veg. Nuts are OK, but no peanuts, as they’re a farmed product. It is almost certainly built on bunkum foundations, as indeed most fad diets are.

Diet is not easy to validate in the deep past, but the clues from genetics suggest that the basis for the Paleo Diet is nuts, even if you’re not allowed to eat peanuts. As with all fad diets it probably works a bit, but not because of the content of the diet itself, but because the act of dieting prompts people to eat less and think more about their food, and not to shovel huge portions of pasta or chips on their supper plates. So go ahead and diet, but don’t pretend that it’s based on some evolutionary precedent. And remember that whatever we did in the deep past, we live longer and better now than at any point in the history of humankind.

The sweetness in milk comes from a sugar called lactose, and lactase seeps out of your stomach lining and slices lactose in half to produce the sugars glucose and galactose. Elegant names are not always a preoccupation of biologists.

borborygmus,

We make crude visual distinctions and effectively meaningless categorizations based on average skin tones, such as black or white.

All skin tones in between exist in abundance. This is not some liberal fantasy, it’s simply a truth that a Pantone swatch of human skin is a continuum.

There’s two types

Alas, a fiction can fly around the world before the truth has managed to pick the sleep from its eyes in the morning.

discomfit

So, what are the chances of this oh-so-northern-European trait going extinct? Roughly, somewhere between none and zero.

ichnofossils

salubrious,

including the Roma, Europe’s largest ethnic minority. (Britons and Americans have traditionally called the Roma “Gypsies,” but this is often considered derogatory.)

most recent common ancestor (MRCA)

hoick

Evolution is an arms race, a permanently fluctuating ping-pong between genes in the hosts that carry them and the organisms they feed on, and the spiraling cycles in the struggle for existence.

The Americas, North and South, comprise a people simultaneously young and old. The “young” is especially prominent in a country such as the United States, where the genetic, political, and cultural picture of its people is defined by immigrants and the descendants of slaves.

The population of all countries is in constant flux, but the modern United States is different, because of this history of slavery, as well as an ever-growing population of South Asians, East Asians, Middle Easterners, and Latinos, who are themselves of multiple lines of descent from Europe, Mesoamerica, and elsewhere.

knapping

pernicious.

The Aleuts were housed in conditions far worse than the 700 Nazis who were captured in North Africa and imprisoned a few hundred miles away in Alaska.

The stigma of a genetic predisposition to alcoholism remains among Native Americans to this day, despite the fact that it is a claim not rooted in fact.

Less than 2 percent of the current population defines itself as Native American, which means that 98 percent of Americans are unable to trace their roots, genetic or otherwise, beyond 500 years on American soil.

fecund

ancestors of no one alive today. Their lines of descent petered out at some point, when they or one of their progeny did not leave any of their own. Conversely, the remaining 80 percent are the ancestor of everyone living today. All lines of ancestry coalesce on every individual in the tenth century.

One way to think of it is to accept that everyone of European descent should have billions of ancestors at a time in the tenth century, but there weren’t billions of people around then, so try to cram them into the number of people that actually were. The math that falls out of that apparent impasse is that all of the billions of lines of ancestry have coalesced into not just a small number of people, but effectively literally everyone who was alive at that time.

So, by inference, if Charlemagne was alive in the ninth century, which we know he was, and he left descendants who are alive today, which we also know is true, then he is the ancestor of ...

Chang factored that into a further study of common ancestry beyond Europe, and concluded in 2003 that the most recent common ancestor of everyone alive today on Earth lived only around 3,400 years ago.