A new method for analyzing modern and archaic human DNA has thrown up some fascinating results. It appears that modern humans (Homo Sapiens) mated earlier and more frequently with an archaic human ancestor, a species of extinct hominins. Moreover, they have found evidence the DNA of this mysterious archaic human ancestor is still part of our modern human genetic inheritance.
An American team of scientists, from leading American universities, embarked upon an ambitious plan to map the flow of genes between different species of hominids. Gene flow is an indication of interbreeding between ancient human species. A new algorithm, known as ARGweaver-D, was developed by Melissa J. Hubisz to achieve the goals of the project. This algorithm allowed researchers to develop a model of the lineages of early humans. Adam Siepel, who took part in the study, stated that “We are trying to build a complete model for the evolutionary history of every segment of the genome, jointly across all of the analyzed individuals” according to Live Science.
Our Mysterious Archaic Human Ancestor and Extinct Humans
During the study, researchers compared the genomes of two Neanderthals, a Denisovan and two modern African individuals. The Neanderthals (Homo neanderthalensis) were an extinct species of humans that died out about 30000 years ago, and once inhabited vast areas of Eurasia. Denisovans are a mysterious species, only known through their DNA, who probably ranged across an area that covered Siberia and East Asia. The samples from modern Africans were selected because they are known not to have Neanderthal nor Denisovan genes.
The spread and evolution of Denisovans (John D. Croft / CC BY-SA 3.0)
Based on the ground-breaking algorithm the researchers were able to develop an ancestral recombination graph, which “includes a tree that captures the relationships among all individuals at every position along the genome, and the recombination events that cause those trees to change from one position to the next,” Siepel told Live Science. The team were able to build up a picture of the extensive interbreeding between different species of hominids and gain insights even into their migration patterns.
DNA Reveals Our Mysterious Archaic Human Ancestor
The researchers wrote in PLOS Genetics that they ‘estimate that the gene flow occurred between 200-300 kya,’ which is 200,000 or 300,000 years ago. And research has already shown that modern humans, Denisovans, Neanderthals interbred in the ancient past. However, using the new algorithm, researchers were able to show that this interbreeding occurred much earlier than once believed. It seems likely that anatomically modern humans left Africa and migrated to Eurasia in an early wave and mated with Neanderthals, before they returned to Africa or died out.
The results from a sample of Denisovan DNA were remarkable. Inverse.com states that the ‘genome contained genetic material that came from an unexpected source – an archaic human ancestor that was neither human, nor Neanderthal, nor Denisovan.’ This was a mystery. Researchers have theorized that the genes may have come from Homo Erectus. An extinct hominin who emerged in Africa about two million years ago, Homo Erectus was the first archaic human to use fire and migrate out of Africa.
The Mystery of Homo Erectus
However, the “story” of Homo Erectus is unproven because we do not have any DNA from this long-extinct human species. Siepel told Live Science that “the genome of that extinct species of human has never been sequenced.” As a result, there is much we still don’t know about human evolution, including if H. Erectus (upright man) is our ancestor. It is also possible that the mysterious DNA found ‘nested’ in the genome sequences comes from a new and unknown archaic human ancestor species.
A reconstruction of Peking Man or Homo erectus pekinensis, a specimens of Homo erectus found in China dating from roughly 750,000 years ago. (Cicero Moraes / Public domain)
The new research indicates that the human tree is much more complex than first thought. Hundreds of thousands of years ago there were four species of humans and they interbred. It appears that the ranges of our archaic human ancestors overlapped and that because of their regular migrations they often mated with different human species. The study also shows the importance of migration in the evolution of both archaic and modern humans.
- New DNA Study Suggests African Humans Interbred With European Neanderthals Way Earlier Than We Think
- Face of the Denisovans? Portrait of a Teen Revealed by Her DNA
- The Widespread Appearance of Neanderthal DNA: Africans Have It Too
Modern Humans Are The Result of Multiple Hybrid Offspring
Siepel told Live Science that “A picture is emerging of a series of distinct but related populations moving around the globe and frequently interacting with one another, with occasional interbreeding events that produced hybrid offspring.” It is not known if these hybrids were fit enough to survive and have offspring. It seems likely that at least some survived and this accounts for the distinctive genetic inheritance of many groups. For example, Tibetans and Pacific Islanders show traces of Denisovan DNA.
These interbreeding events were very important in the evolution of modern humans. Science Daily reports that “15% of these ‘super-archaic’ regions may have been passed down to modern humans.’’ This means that genes which flowed between different archaic human species are still part of modern people’s genetic make-up, including those from an unknown archaic human ancestor.
Clearly, the newly developed algorithm can help researchers to delve deeper into the evolutionary history of archaic and modern humans. Siepel told Science Daily that “It seems to be especially powerful for detecting ancient introgression” or interbreeding between species. For example, the algorithm can be adapted to help experts to understand mating occurrences between prehistoric wolves and dogs. So far, this powerful algorithm has already shown the we modern humans likely have an archaic human ancestor who is still unknown and unnamed.
Top image: Male and female Neanderthals were one of our ancestors, but recent DNA research suggests we also have a mysterious archaic human ancestor. Credit: Gorodenkoff / Adobe Stock
By Ed Whelan
Unknown Human Ancestor
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Hello Ed,
Great article thanks for sharing you know it's funny but this article reminds me of the National Geographic Documentary In Search of Adam which aired 2008 (you can watch it on ytube), The scientist in the program continually touched basis with the unraveling of the Root's I did think that the documentary should have been at least and hour in thirty minutes it felt like a rush job.
While searching for Adam they did a slight detour by focusing on Thomas Jefferson the DNA was proof Thomas had Children by Sally his Slave woman the thing is that Thomas blood shows that he's actually Lebanon and Syrian meaning his face is White but his blood is Middle Eastern.
How in the world did the Middle East get into England?
Then of course there's Dr. Henry Louis Gates. Jr. and his program on PBS Finding you Root's he and his Team have since found Levi one of the Tribes mentioned in The Bible, through Levi the Team seem to have Abraham's DNA signature I guess that makes him Scientific Abraham.
Dr. Gates team also researched the Kenyan Actress Lupita the Team was very excited by what they discovered with her Scientific Eve this one discovery astonished the Dr. Gates and his Team. The third significant discovery with Finding your Root's Azenaski Jews are routinely being found.
Hope the unknown ancestor is found.
“A picture is emerging of a
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“A picture is emerging of a series of distinct but related populations moving around the globe and frequently interacting with one another, with occasional interbreeding events that produced hybrid offspring. It is not known if these hybrids were fit enough to survive and have offspring. It seems likely that at least some survived..."
Likely? How on Earth did they pass on their genes if none of their offspring survived to successfully breed?
The correct way to put it is that while mortality without breeding success may have been the norm for such hybrid offspring, only some needed to be successful to pass on their genes and if some of those genes conferred advantages, the descendants may well have become more numerous over subsequent generations.
Seriously, I never cease to wonder at the rubbish that can be served up by the supposedly well-educated.
Cataibh
High-school dropout.
Nil university education.
They need to add those
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They need to add those mummies from Peru to their DNA mix.
Jefferson and the slave woman
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As far as DNA and the middle east. Mesopotamia was the Origin of Western Europeans. Regarding the Slave woman, Jefferson's DNA could be from thousands of sources. The tree has many branches. This DNA reference to Jefferson is a political agenda.
Jefferson DNA
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In reply to Jefferson and the slave woman by Sir Clerke
Hello Sir Clerke,
National Geographic is far from a political agenda; they are strictly Science. The program did make known to the many roots that they needed to untangle before even finding Scientific Adam or if they would find him at all.
I knew I was watching National Geographic when they continually kept mentioning Evolution. This article shared by Ancient Origins reminded me of the science documentary In Search of Adam, 2008.
Happily for me I have been able to re-watch it on ytube.
The sound was bad; but, it was still enjoyable, for me too watch.
I mean in the program the Geneticist went looking for Ghenis Khan because some people whose ancestry was in Asia believed him to be their Great-grandfather.
That was exciting, I was beginning too think that Ghenis Khan was a Myth; but too know something like DNA could quite possibly trace him, Sweet!