Tag: Denisovan

Early Humans Hooked Up With Neanderthals All The Time

Early humans had mated with Neanderthals and other primitive cousins far more often than thought in a world of debauchery, according to a new study.

Researchers found that interbreeding happened “multiple times” as our ancestors began to pour out of Africa and mingle with more species around 75,000 years ago.

The analysis of Neanderthal DNA in modern East Asians and Europeans found the assumption it was rare is wrong. It happened often — over a period of up to 35,000 years.

Data from the 1,000 Genomes project — which has mapped the DNA of 1,000 people from around the world — suggests an environment of rampant promiscuity.

It was a complex web of relationships in which individuals had intercourse with members of their own group — and different early humans, or hominins.




Co-author Joshua Schraiber said: “I do think there was probably much more interbreeding than we initially suspected. Some of the fantastical aspects come from a lack of a clear definition of ‘species’ in this case.

“It is always very hard to know if an extinct group constituted a different species or not.

“My guess is that any time two different human groups lived in the same place at the same time for a while, they probably had some sort of breeding contact.”

Recent studies have found Denisovans, another extinct relative, had sex with Neanderthals and humans on numerous occasions.

The Denisovan species was only discovered in southern Siberia a decade ago. They were genetically distinct from both Neanderthals and humans.

There were at least three different human forms on Earth only 40,000 years ago — all having an intercourse with each other. And there may have been more.

When anatomically modern humans dispersed from Africa, they encountered Neanderthals in Europe and Asia.

This left a signature in our genomes — with about 2 percent inherited from the Neanderthal. This DNA influences our immune system and the diseases we develop.

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In A Lost Baby Tooth, Scientists Find Ancient Denisovan DNA

Denisovans

More than 100,000 years ago in a Siberian cave there lived a child with a loose tooth. One day her molar fell out, and fossilized over many millenniums, keeping it safe from the elements and the tooth fairy.

But she wasn’t just any child. Scientists say she belonged to a species of extinct cousins of Neanderthals and modern humans known today as the Denisovans.

And in a paper published last Friday in the journal Science Advances, a team of paleoanthropologists reported that she is only the fourth individual of this species ever discovered.

“We only have relatively little data from this archaic group, so having any additional individuals is something we’re very excited about,” said Viviane Slon, a doctoral candidate at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and lead author of the study.

Denisovans cave

The scant fossil record for these ancient hominins previously included only two adult molars and a finger bone. The Denisovans were only correctly identified in 2010 by a team of researchers led by Svante Paabo.

Scientists exploring Denisova Cave in the Altai Mountains discovered the worn baby tooth in 1984 and labeled it ‘Denisova 2.’ At the time, its origins were a mystery.

But now, after performing DNA analysis on the deciduous, or baby tooth, researchers say it was one of the elusive Denisovans.

“We think based on the DNA sequences that ‘Denisova 2’ is at least 100,000 years, possibly 150,000 years old. Or a bit more,” said Ms. Slon. “So far it makes it the oldest Denisovan.”

Denisovans

To determine the origins of ‘Denisova 2’ the team first performed a CT scan of the tooth to preserve its structure for future studies.

After sequencing the DNA she compared genetic information from the sample with genetic data already collected from Denisovans, Neanderthals and modern humans.

“We saw it was most similar to Denisovan mitochondrial genomes,” she said. “That was exciting because that was a good indication that this was another Denisovan individual.”

Bence Viola, a paleoanthropologist from the University of Toronto and an author on the paper, said there was not too much to be learned from studying the tooth’s morphology or appearance.




The genetic analysis, on the other hand, provided the keys to learning more about the species. He said the genetic study was something the team most likely could not have done five years ago without destroying the tooth.

“For a long time we didn’t want to work on it because it’s such a small specimen,” he said.

But by drilling into the tooth and performing the genetic analysis the scientists were able to not only figure out who it belonged to, but also provide relative dates for when the Denisovan lived.

The study also suggests that the species had less genetic variability than modern humans, but more genetic diversity than seen in Neanderthal nuclear DNA.

Dr. Bernard A. Wood, a professor of human origins at the Center for the Advanced Study of Human Paleobiology at George Washington University, said the paper demonstrated the power of molecular biology as a tool for paleoanthropology.

“Talk about extracting blood from a stone,” he said, “this is extracting treasure from a tooth.”

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Pass it on: New Scientist