Why you should care
Because there’s a little Neanderthal in all of us.
The classic textbook illustration of human evolution shows a single-file line beginning with an ape on all fours and ending with modern-day, upright Homo sapiens. But new DNA sequencing technology has revealed that human prehistory wasn’t so orderly. Homo sapiens didn’t emerge after Neanderthals; they lived among each other … and they rubbed more than just elbows.
Come closer, dear reader. This is a story about prehistorical sex and the woman who studies it for a living.
Qiaomei Fu is a leader among a cadre of scientists applying modern, next-generation gene-sequencing techniques to the study of ancient humans. A geneticist at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing, she has so far unearthed a prehistory shaped by dramatic displacement, migration — and interspecies action à la The Clan of the Cave Bear. “So many papers [of hers] are really groundbreaking,” says Rasmus Nielsen, a theoretical evolutionary geneticist at the University of California, Berkeley. “She is regarded as one of the young stars of genetic anthropology,” thanks to her use of cutting-edge technology to analyze often highly degraded and contaminated ancient DNA, a longstanding hurdle in the field. Besides answering big existential questions about our own origins, these techniques might also have medical applications, shedding light on genetic variants that underlie disease, Nielsen says.
…Sex between modern humans and Neanderthals went on for longer than we’d previously thought.
Fu grew up climbing trees and catching fish from Poyang Lake in southeastern China. In college, she chose an interdisciplinary major that combined archaeology, chemistry, math and computer programming. When she arrived at the Max Planck Institute to pursue a Ph.D. in ancient human genomics, she didn’t have any genetics experience — but thanks to her math and computing background, she mastered next-generation sequencing techniques even faster than her classmates who had studied biology. Then it was off to Harvard for postdoctoral research in population genetics.
Meanwhile, Fu published a string of studies shedding light on our ancestors’ raunchy pasts. A 2014 Nature paper detailed her sequencings of the oldest known Homo sapiens DNA from a 45,000-year-old femur unearthed in Siberia, a specimen named Ust’-Ishim. Two percent of the femur genome carried Neanderthal DNA — about the same percentage found in our genomes, but for one slight difference. During sexual reproduction, maternal and paternal chromosomes recombine, resulting in shorter Neanderthal DNA fragments with every generation. But the fragments in the femur genome resembled those of a human who lived around 200 to 300 generations ago, suggesting when modern humans interbred with Neanderthals — around 50,000 to 60,000 years ago.
Fu and her colleagues also sequenced the DNA of a 40,000-year-old human jawbone — from “Oase man” — discovered in a Romanian cave. Since Oase man is younger than Ust’-Ishim, the researchers expected his genome to contain shorter fragments of Neanderthal DNA. But Oase man’s genome contained not only more Neanderthal DNA, but longer stretches of it. Which means? Oase man might have had a Neanderthal for a great-great-grandparent, Fu says, suggesting that sex between modern humans and Neanderthals went on for longer than we’d previously thought. Fu has also found that Neanderthal-human sex went down in Europe in addition to the previously known occurrences in the Middle East.
With delicate, girlish features and a shy smile, Fu speaks with hushed intensity when she recounts the Oase man incident. After finding his unusually high levels of Neanderthal DNA, she says she remained curious despite the limited, contaminated evidence with which she was operating. She designed an archaic DNA array and spent Christmas and New Year’s hunkered down in her office, analyzing the data. When the analysis confirmed her hunch, she rushed to show it to her advisers, elated. “It was really almost like a dream,” she says. Iosif Lazaridis, Fu’s former colleague at Harvard, recalls her intellectual hunger. “She always wanted to learn more,” he says. “She was never satisfied with just writing a simple paper.”
Fu’s research has also revealed a turbulent Ice Age Europe, and found that a new genetic component related to modern-day humans from the Near East appeared in Europe around 14,000 years ago — during the first major warming period — which may reflect migrations or population shifts in Europe at the end of the last Ice Age. Nielsen calls the Nature paper detailing these findings “a game-changer”: “What this particular paper does is a technological achievement,” he says. “Something that was very much debated before we can now test.”
To be sure, future investigations might yield data that challenges Fu’s findings, Lazaridis says. “We will see whether … we have to change the theory or whether it will stand the test of time.” While next-generation sequencing techniques are revolutionizing the study of ancient history, there remains “a lot of things we don’t know,” Fu says.
But for her, the unknowns are a propelling force, taking her from Europe to China, where she’s now founded her own lab. Next up, she wants to demystify the history of Ice Age East Asia and, later, to identify archaic humans who lived in the region — and, of course, what they were doing under the prehistoric covers.