Tag: Denisovans

Tracking history before DNA

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F.Chen et al./Nature

Over the past two decades, DNA retrieved from ancient fossils has transformed scientists’ understanding of human evolution. Analysis of the similarities and differences in the DNA of different hominin groups has allowed researchers to map out the tangled family tree in a way that was previously not possible. And genetic material has led to some major finds, such as the discovery of Denisovans in the first place…

Ancient DNA has also left geographical blind spots. DNA degrades faster in warm environments, so although a 100,000-year-old specimen found in a cold Siberian cave might still harbour genetic material, a fossil that has spent that long in the heat of Africa or southeast Asia generally will not. As a result, little is known about the genetics of even relatively recent hominins from these regions, such as H. floresiensis…

Now researchers are hoping that protein analysis might begin to fill in some of those blanks. The idea is not new: as early as the 1950s, researchers had reported finding amino acids in fossils. But for a long time, the technology needed to sequence ancient proteins just didn’t exist … That changed in the 2000s, after researchers realized that mass spectrometry — a technique used to study modern proteins — could also be applied to ancient proteins. Mass spectrometry essentially involves breaking down proteins into their constituent peptides (short chains of amino acids) and analysing their masses to deduce their chemical make-up.

RTFA. Fascinating as paleontology can always be. Learning the where and when of how we got to here and now. True science never walks away from a problem because it’s difficult. Even when it takes generations to resolve.

The diaspora of modern humans across Eurasia — update and revision

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Migration routes — Click to enlarge

❝ Most people are now familiar with the traditional “Out of Africa” model: modern humans evolved in Africa and then dispersed across Asia and reached Australia in a single wave about 60,000 years ago. However, technological advances in DNA analysis and other fossil identification techniques, as well as an emphasis on multidisciplinary research, are revising this story. Recent discoveries show that humans left Africa multiple times prior to 60,000 years ago, and that they interbred with other hominins in many locations across Eurasia.

❝ A review of recent research on dispersals by early modern humans from Africa to Asia by researchers from the Max Planck Institute for the Science of Human History and the University of Hawai’i at Manoa confirms that the traditional view of a single dispersal of anatomically modern humans out of Africa around 60,000 years ago can no longer be seen as the full story. The analysis, published in the journal Science, reviews the plethora of new discoveries being reported from Asia over the past decade, which were made possible by technological advances and interdisciplinary collaborations, and shows that Homo sapiens reached distant parts of the Asian continent, as well as Near Oceania, much earlier than previously thought. Additionally, evidence that modern humans interbred with other hominins already present in Asia, such as Neanderthals and Denisovans, complicates the evolutionary history of our species.

The Max Planck Institute is the gold standard for research into the evolutionary biology of homo sapiens. When original discussions stretched around the world at the turn of the 21st Century, debate and discussion took over a great deal of public and non-institutional dialogue on the latest discussions of evolution. Scuence readers and writers as well as core researchers were all involved.

I spent about 2 years getting my head around the results of the first DNA analysis providing deeper genetic and chronological analysis previously impossible. While spirited debate was often the order of the day – well above the perpetual attempts to educate superstitious folk stuck into biblical fiction – I have rarely so enjoyed the weekly expansion of knowledge rolling out the doors of the Max Planck Institute like tides changing the face of the intellectual Earth after an Ice Age.

Oh, yeah. Between 3 and 4% of my overall DNA is Neanderthal. Never was one of those straight-up white guys. 🙂

As humans evolved – we had sex with all of our relatives!

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Our species may have bred with a now extinct lineage of humanity before leaving Africa, scientists say.

Although we modern humans are now the only surviving lineage of humanity, others once roamed the Earth, making their way out of Africa before our species did, including the familiar Neanderthals in West Asia and Europe and the newfound Denisovans in East Asia. Genetic analysis of fossils of these extinct lineages has revealed they once interbred with modern humans, unions that may have endowed our lineage with mutations that protected them as we began expanding across the world about 65,000 years ago.

Now researchers analyzing the human genome find evidence that our species hybridized with a hitherto unknown human lineage even before leaving Africa, with approximately 2 percent of contemporary African DNA perhaps coming from this lineage. In comparison, recent estimates suggest that Neanderthal DNA makes up 1 percent to 4 percent of modern Eurasian genomes and Denisovan DNA makes up 4 percent to 6 percent of modern Melanesian genomes.

“We need to modify the standard model of human origins in which a single population transitioned to the anatomically modern state in isolation — a garden of Eden somewhere in Africa — and replaced all other archaic forms both within Africa and outside Africa without interbreeding,” researcher Michael Hammer, a population geneticist at the University of Arizona in Tucson, told LiveScience. “We now need to consider models in which gene flow occurred over time…”

“We think there were probably thousands of interbreeding events,” Hammer said. “It happened relatively extensively and regularly.”

I don’t think the “extensive and regular” part is a surprise either. It may upset some boring, straight-laced and narrow-minded pundits; but, evolution doesn’t pay any attention to ideology.