The Melanesian people probably never thought they’d be so crucial to our understanding of humanity’s origins. But when a group of scientists decided to look closer into the DNA of the remote Pacific islanders, they made a startling discovery. And it’s one that could turn our comprehension of ancestry on its head.
Melanesia is the name for a broad region of Oceania, including four countries and some smaller islands. Vanuatu, Fiji, Papua New Guinea and the Solomon Islands all fall under the sub-region. And it’s the populations of those areas that sparked the interests of scientists.
The Melanesian islands are isolated from the rest of Asia and Australasia by the Pacific Ocean. This means their ancestry proves key in discovering how humans traveled across the region hundreds of thousands of years ago.
Previously, genetic analysis has shown that their ancestors were two groups of hominids, who bred upon meeting. The first of these is the more commonly-known Neanderthal, with whom all non-Africans share some DNA. The second group of hominids is less well-known: the Denisovans.
At some point between 60,000 to 100,000 years ago, it’s believed some of modern man’s early ancestors left Africa. They went to Eurasia, leading them to make contact with the Neanderthals and Denisovans there. Because they bred with their hominid cousins, traces of their DNA entered the Eurasian genome.
While most people are aware of the Neanderthal species, few know of the Denisovans. Believed to be a related species to the Neanderthals, they were mainly found in Siberia. However, it appears they could have been living as far south as Southeast Asia.
Apparently, 200,000 or so years back, the two hominids – Neanderthal and Denisovans – split from a shared ancestor. However, it’s thought they branched from modern humans much further ago, around 600,000 years back. And although there have been plenty of Neanderthal fossils discovered, barely any Denisovan DNA exists.
And, while people in Europe have no trace of Denisovan DNA in their genome, the Chinese carry a minuscule 0.1 percent. However, when it comes to the Melanesian people, this figure rises. Indeed, Denisovan DNA has previously been calculated as comprising as much as six percent of their genetic makeup.
It’s no surprise, then, that the Melanesian people are of great interest to scientists. After all, they may help us truly grasp our own ancestry by lending more clues about our genetic background.
However, a study published in October 2016 found there may not be as much Denisovan DNA in Melanesians as previously thought. Statistical geneticist Ryan Bohlender, of the University of Texas, told Science News that the real figure could actually be closer to 1.1 percent.
Clearly, the gap between the two figures leaves space for something – or someone – else. But who or what is a total mystery. The only decision the scientists could come to was that a third, unknown group of hominids could have bred with the ancient Melanesian people.
This discovery sent shock waves through the scientific community. If true, it proves that the history of humanity is far more complicated than thought. Indeed, the findings could even turn the theory of evolution on its head.
Bohlender and his team presented the results of their study in Vancouver, explaining, “We suggest that a third archaic population related more closely to Neanderthal and Denisova than to modern humans introgressed into the San genomes studied here.”
The research group estimate that this third, unknown group split from their shared ancestor some 440,000 years back in time. That means they branched off much earlier than the Neanderthals and Denisovans.
Concluding, Bohlender said, “Overall, our findings confirm the human family tree is more complicated than we think it is. Other archaic populations are likely to have existed, like the Denisovans, who we didn’t know about.”
Indeed, the team’s findings are backed up by another study from earlier in 2016 by scientists at Denmark’s Natural History Museum. This study included an analysis of Melanesian DNA, taken from residents of remote Papa New Guinea and aboriginal Australians.
Like Bohlender’s research, the study found a type of DNA that was alike to the Denisovans, but far removed enough that it could not be classified as such. Therefore, the results again pointed to a third type of hominid.
Sadly, there’s no concrete evidence that this third group of early humans even existed. Researchers haven’t found any fossils containing the DNA of this group. However, that doesn’t mean the elusive third hominids never existed: the rarity of fossils in general means that the DNA-containing types could still be out there.
Meanwhile, it’s also possible that scientists’ identification of Denisovan DNA isn’t as accurate as they’d like. Why? Because the only remnants of the species found to date are some teeth and a single finger bone. That’s not much to work with. This is just one reason that Bohlender’s results may not be 100 percent valid.
Still, if Bohlender and his team’s research did prove correct, the consequences for the scientific community – and our understanding of our own ancestry – are groundbreaking. Who’s up for rewriting the theory of evolution?