"Long before it's in the papers"
June 22, 2015

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Human may have had Neanderthal great-great-grandparent

June 22, 2015
Courtesy of the Howard Hughes 
Medical Institute
and World Science staff

Ge­neti­cists have an­a­lyzed an­cient DNA from an old jaw­bone and con­clud­ed that it be­longed to a mod­ern hu­man whose re­cent an­ces­tors in­clud­ed Ne­an­der­thals.

Ar­chae­o­lo­gists found the jaw­bone—attributed to a Eu­ro­pe­an about 40,000 years ago—in Ro­ma­nia in 2002.

The Oase Cave jawbone (Credit: MPI f. Evo­lution­ary Anthro­polo­gy/ Paa­bo)


The per­son may have had a Ne­an­der­thal an­ces­tor as re­cently as four to six genera­t­ions back, and it shows that mix­ing be­tween mod­ern hu­mans and Ne­an­der­thals oc­curred soon af­ter an­a­tom­ic­ally mod­ern hu­mans ar­rived in Eu­rope, sci­en­tists claim.

Ne­an­der­thals lived in Eu­rope un­til about 35,000 years ago, dis­ap­pear­ing just as mod­ern hu­mans spread across the con­ti­nent. The new stu­dy, co-led by Da­vid Re­ich of Har­vard Med­i­cal School and Svante Pääbo at the Max Planck In­sti­tute in Ger­ma­ny, is re­ported in the June 22 is­sue of the jour­nal Na­ture.

“Be­fore 45,000 years ago, the only hu­mans in Eu­rope were Ne­an­der­thals. Af­ter 35,000 years ago, the only hu­mans in Eu­rope were mod­ern hu­mans. This is a dra­mat­ic tran­si­tion,” Re­ich said. 

There is ar­chae­o­log­i­cal ev­i­dence that mod­ern hu­mans in­ter­acted with Ne­an­der­thals, he added: Changes in tool mak­ing tech­nol­o­gy, bur­i­al rit­u­als, and body de­cora­t­ion imply a cul­tur­al ex­change. “But we have very few skele­tons from this pe­ri­od,” Re­ich said.

The jaw­bone is “amaz­ing,” Re­ich said. It was found along with the skull of an­oth­er per­son in a cave called Oase. No ar­ti­facts turned up near­by. The jaw­bone’s fea­tures were pre­dom­i­nantly those of mod­ern hu­mans, but some Ne­an­der­thal traits were al­so ap­par­ent, and the an­thro­po­lo­gists pro­posed a re­cently mixed an­ces­try.

Pääbo and Re­ich teamed up to an­a­lyze its DNA. Trace amounts of an­cient DNA can be re­cov­ered from bones as old as the Oase jaw­bone, but to an­a­lyze it, that an­cient DNA must be sifted out of an over­whelm­ing amount of DNA from oth­er or­gan­isms. When Qiaomei Fu, who was a grad­u­ate stu­dent in Pääbo’s lab, ob­tained DNA from the bone, most of it was from mi­crobes that lived in the soil where the bone was found. Of the frac­tion of a per­cent that was hu­man DNA, most had been in­tro­duced by peo­ple who han­dled the bone af­ter its disco­very.

Us­ing meth­ods pi­o­neered in Pääbo’s lab, Fu en­riched the pro­por­tion of hu­man DNA in the sam­ple, us­ing ge­net­ic probes to re­trieve pieces of DNA that spanned any of 3.7 mil­lion po­si­tions in the hu­man ge­nome that are con­sid­ered use­ful in eval­u­at­ing varia­t­ion be­tween hu­man popula­t­ions. 

Most of the DNA she ended up with was hu­man, but came from peo­ple who had han­dled the jaw­bone since 2002, rath­er than the jaw­bone it­self. Fu, who is now a post­doc­tor­al re­search­er in Re­ich’s group, solved that prob­lem by re­strict­ing her anal­y­sis to DNA with a kind of dam­age that de­ter­i­o­rates the mol­e­cule over tens of thou­sands of years.

Once they had dis­carded con­tam­i­nat­ing DNA, Re­ich’s team could com­pare the fos­sil’s ge­nome to ge­net­ic da­ta from oth­er groups. Through a se­ries of sta­tis­ti­cal anal­y­ses, a sur­pris­ing con­clu­sion emerged. “The sam­ple is more closely re­lat­ed to Ne­an­der­thals than any oth­er mod­ern hu­man we’ve ev­er looked at be­fore,” Re­ich said. “We es­ti­mate that six to nine per­cent of its ge­nome is from Ne­an­der­thals. This is an un­prec­e­dent­ed amount. Eu­ro­pe­ans and East Asians to­day have more like two per­cent.”

Re­ich said he found seg­ments of in­tact Ne­an­der­thal DNA large enough to point to the re­cent an­ces­try. “In the last few years, we’ve doc­u­mented in­ter­breed­ing be­tween Ne­an­der­thals and mod­ern hu­mans, but we nev­er thought we’d be so lucky to find some­one so close to that even­t,” he said.

But the Oase per­son is­n’t re­spon­si­ble for pass­ing his Ne­an­der­thal an­ces­try on to pre­s­ent day hu­mans, he said, as there is no ev­i­dence this in­di­vid­ual is closely re­lat­ed to lat­er Eu­ro­pe­ans. 

“This sam­ple, de­spite be­ing in Ro­ma­nia, does­n’t yet look like Eu­ro­pe­ans to­day,” he said. “It is ev­i­dence of an in­i­tial mod­ern hu­man oc­cupa­t­ion of Eu­rope that did­n’t give rise to the lat­er popula­t­ion. There may have been a pi­o­neer­ing group of mod­ern hu­mans that got to Eu­rope, but was lat­er re­placed by oth­er groups.”


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Geneticists have analyzed ancient DNA from an old jawbone and concluded that it belonged to a modern human whose recent ancestors included Neanderthals. Archaeologists found the jawbone—attributed to a European about 40,000 years ago—in Romania in 2002. The person may have had a Neanderthal ancestor as recently as four to six generations back, and it shows that mixing between modern humans and Neanderthals occurred soon after anatomically modern humans arrived in Europe, scientists claim. Neanderthals lived in Europe until about 35,000 years ago, disappearing just as modern humans spread across the continent. The new study, co-led by David Reich of Harvard Medical School and Svante Pääbo at the Max Planck Institute in Germany, is reported in the June 22 issue of the journal Nature. “Before 45,000 years ago, the only humans in Europe were Neanderthals. After 35,000 years ago, the only humans in Europe were modern humans. This is a dramatic transition,” Reich said. There is archaeological evidence that modern humans interacted with Neanderthals, he added: Changes in tool making technology, burial rituals, and body decoration imply a cultural exchange. “But we have very few skeletons from this period,” Reich said. The jawbone is “amazing,” Reich said. It was found along with the skull of another person in a cave called Oase. No artifacts turned up nearby. The jawbone’s features were predominantly those of modern humans, but some Neanderthal traits were also apparent, and the anthropologists proposed a recently mixed ancestry. Pääbo and Reich teamed up to analyze its DNA. Trace amounts of ancient DNA can be recovered from bones as old as the Oase jawbone, but to analyze it, that ancient DNA must be sifted out of an overwhelming amount of DNA from other organisms. When Qiaomei Fu, who was a graduate student in Pääbo’s lab, obtained DNA from the bone, most of it was from microbes that lived in the soil where the bone was found. Of the fraction of a percent that was human DNA, most had been introduced by people who handled the bone after its discovery. Using methods pioneered in Pääbo’s lab, Fu enriched the proportion of human DNA in the sample, using genetic probes to retrieve pieces of DNA that spanned any of 3.7 million positions in the human genome that are considered useful in evaluating variation between human populations. Most of the DNA she ended up with was human, but came from people who had handled the jawbone since 2002, rather than the jawbone itself. Fu, who is now a postdoctoral researcher in Reich’s group, solved that problem by restricting her analysis to DNA with a kind of damage that deteriorates the molecule over tens of thousands of years. Once they had discarded contaminating DNA, Reich’s team could compare the fossil’s genome to genetic data from other groups. Through a series of statistical analyses, a surprising conclusion emerged. “The sample is more closely related to Neanderthals than any other modern human we’ve ever looked at before,” Reich said. “We estimate that six to nine percent of its genome is from Neanderthals. This is an unprecedented amount. Europeans and East Asians today have more like two percent.” Reich said he found segments of intact Neanderthal DNA large enough to point to the recent ancestry. “In the last few years, we’ve documented interbreeding between Neanderthals and modern humans, but we never thought we’d be so lucky to find someone so close to that event,” he said. But the Oase person isn’t responsible for passing his Neanderthal ancestry on to present day humans, he said, as there is no evidence this individual is closely related to later Europeans. “This sample, despite being in Romania, doesn’t yet look like Europeans today,” he said. “It is evidence of an initial modern human occupation of Europe that didn’t give rise to the later population. There may have been a pioneering group of modern humans that got to Europe, but was later replaced by other groups.”