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Something on the order of 107 billion modern humans have existed, though this number depends on when exactly you start counting.
We only have to go back a few dozen centuries to see that most of the 7 billion of us alive today are descended from a tiny handful of people, the population of a village.
A genome is much more useful if it can be compared to another, and that includes genomes from other species.
In most cells, you carry two complete sets of chromosomes, one set inherited from your mother, one from your father, twenty-three pairs in total all neatly stored in the nucleus, the little nut in the center of cells.
twenty-two of those pairs are the same as each other (called autosomes), and one of those pairs is not a pair. The pair that is not a pair are the sex chromosomes.
there’s a minuscule but terribly important bit of DNA that is not in the nucleus, but instead sits inside the mitochondria—the tiny but powerful energy generation units that all complex life relies on.
In contrast to the scraggy Y chromosome, mitochondrial DNA (mtDNA) is only passed from mother to child.
The Out of Africa hypothesis remains completely intact in principle, but the dates and the overall flow have profoundly changed with evidence provided by ancient DNA.
our genomes are slowly purging themselves of Neanderthal DNA, which suggests that these matings were not to our advantage, but not massively disadvantageous.
The observation that there is less Neanderthal DNA on our Xs implies that the first encounters we had with them that resulted in procreation were male Neanderthals with female Homo sapiens.
Altai Mountains loom out of the ground near the Russian borders with China and Mongolia, and they are icy cold. This land is harsh. There’s a cave in this hinterland of Siberia, called Denisova,
The number of differences in her DNA was twice as many as between us and the Neanderthals,
This is an absence of evidence, which we scientists like to remind people is not the same as evidence of absence.
The comparison in the new genomes showed that Denisovans and Neanderthals were more closely related to each other than either was to any living human.
the real kicker came with the revelation that Denisovan DNA was alive and well in contemporary Melanesians—the indigenous people of Fiji, Papua New Guinea, and a scattering of islands off the northeast coast of Australia.
The Neanderthals and the Denisovans split off from the lineage that ended in us some 400,000 years ago. But if you look hard enough, the Denisovan genome looks slightly more different from ours than it should.
family trees are never trees in the way that we draw them in historical pedigrees, or in science papers when looking at a few closely related species, or even as Darwin scribbled so perceptively in his notebook in 1837.
Those ancient people never went extinct—we just merged.
Amylase digests starchy, carbohydrate-rich foods, and helps generate glucose from them, which would provide much needed energy for the evolving and highly energetic brain.
Estimates are that the hunter-gatherers who were all but wiped out by the agricultural revolution numbered around 2 million 12,000 years ago.
We humans are a technological species, science is in our souls, and farming is a technology quite the opposite of natural.
Good quote
The first European Homo sapiens were the hunter-gatherers who had moved up from Africa via central Eurasia 40,000 years before, and overlapped and mated with the indigenous Neanderthals.
And then around 5,000 years ago, another major wave of easterners arrive. The Yamnaya came from the Russian Steppes, driving sheep, riding wagons, making bronze jewelry, and covering their dead in ochre as part of ritual burials.
today’s Siberians are more like East Asians, but the ancient Siberians were more like Native Americans, mixed in with some northern Eurasian.
We know that the lactase persistence gene was selected by evolution, and didn’t just drift into ubiquity, so the simulation trots out a setup where that version of the lactase gene supersedes the versions in the hunters and milk-less farmers.
Genes change culture, culture changes genes. Farming has been arguably the single greatest force in changing human culture and biology.
At least eleven genes appear to have a direct role in determining skin and hair color.
Red hair is caused by changes in a single gene, and exists in the overall global population at about 4 to 5 percent,
Every known organism has parasites, and the relationship between host and predator has been a major driver of many aspects of evolution.
When a force of nature is this powerful and this aggressive, it can leave its signature in our DNA too.
although DNA from ancient Europeans is now readily available, there’s virtually none from Africans. And the reason is largely to do with heat.
Today, the emerging theory is that the people up in the Bluefish Caves some 24,000 years ago were the founders, and that they represent a culture that was isolated for thousands of years up in the cold north, incubating a population that would eventually seed everywhere else.
Anzick is firm and final proof that North and South America were populated by the same people.
Most black people in the United States cannot trace their genealogy with much precision because of the legacy of slavery.
Genetic ancestry tests will not tell you what tribe you are a member of. But we do know enough about the genomes of indigenous Americans for it to show up in a blurry, highly generalized way.
Ancestry is a matted web.
The Life of Charles the Great. The very fact that this account exists—probably the first biography of a European ruler—is testament to how important he was (or at least was seen to be). In many European languages, the word king is itself derived from Charlemagne’s name.
A thousand years in the past, the numbers say something very clear, and a bit disorienting. One fifth of people alive a millennium ago in Europe are the 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.
In 2013, geneticists Peter Ralph and Graham Coop showed that DNA says exactly the same thing as Chang’s mathematical ancestry: Our family trees are not trees at all, but entangled meshes.
You are of royal descent, because everyone is. You are of Viking descent, because everyone is. You are of Saracen, Roman, Goth, Hun, Jewish descent, because, well, you get the idea.
There are only really a couple of definitive unequivocal statements that we can make about your origins in the deep past. The first is that 100,000 years ago we were all African. At that time, there were no Homo sapiens anywhere on Earth apart from in Africa, as far as we know.
