A third extinct human relative.
Hints of an unidentified, extinct human species have been found in the DNA of modern Melanesians – those living in a region of the South Pacific, northeast of Australia.
According to new genetic modelling, the species is unlikely to be Neanderthal or Denisovan – two ancient species that are represented in the fossil record – but could represent a third, unknown human relative that has so far eluded archaeologists.
“We’re missing a population, or we’re misunderstanding something about the relationships,” Ryan Bohlender, a statistical geneticist from the University of Texas, told Tina Hesman Saey at Science News.
Bohlender and his team have been investigating the percentages of extinct hominid DNA that modern humans still carry today, and say they’ve found discrepancies in previous analyses that suggest our mingling with Neanderthals and Denisovans isn’t the whole story.
It’s thought that between 100,000 and 60,000 years ago, our early ancestors migrated out of Africa, and first made contact with other hominid species living on the Eurasian landmass.
This contact left a mark on our species that can still be found today, with Europeans and Asians carrying distinct genetic variants of Neanderthal DNA in their own genomes.
And that’s not all they’ve given us.
Earlier this year, researchers investigated certain genetic variants that people of European descent inherited from Neanderthals, and found that they’re associated with several health problems, including a slightly increased risk of depression, heart attack, and a number of skin disorders.
And a separate study published earlier this month found evidence that modern genital warts – otherwise known as the human papillomavirus (HPV) – were sexually transmitted to Homo sapiens after our ancestors slept with Neanderthals and Denisovans once they left Africa.
While our relationship with Neanderthals has been widely researched, how we interacted with the Denisovans – the distant cousins of Neanderthals – is less clear.
The problem is that Neanderthals are well represented in the fossil record, with many remains having been uncovered across Europe and Asia, but all we have of the Denisovans is a lone finger bone and a couple of teeth that were found in a Siberian cave in 2008.
Using a new computer model to figure out the amount of Neanderthal and Denisovan DNA carried by modern humans, Bohlender and his colleague found that Europeans and Chinese people carry a similar amount of Neanderthal DNA: about 2.8 percent.
That result is pretty similar to previous studies have estimated that Europeans and Asians carry, on average, between 1.5 and 4 percent Neanderthal DNA.
But when they got to Denisovan DNA, things were a bit more complicated, particularly when it came to modern populations living in Melanesia – a region of the South Pacific that includes Vanuatu, the Solomon Islands, Fiji, Papua New Guinea, New Caledonia, West Papua, and the Maluku Islands.
“Europeans have no hint of Denisovan ancestry, and people in China have a tiny amount – 0.1 percent, according to Bohlender’s calculations. But 2.74 percent of the DNA in people in Papua New Guinea comes from Neanderthals.
And Bohlender estimates the amount of Denisovan DNA in Melanesians is about 1.11 percent, not the 3 to 6 percent estimated by other researchers.
While investigating the Denisovan discrepancy, Bohlender and colleagues came to the conclusion that a third group of hominids may have bred with the ancestors of Melanesians.”
“Human history is a lot more complicated than we thought it was,” he told her.
This find is supported by a separate study by researchers from the Natural History Museum of Denmark, who analysed DNA from 83 Aboriginal Australians and 25 locals from the Papua New Guinea highlands.
As we reported last month, this was the most comprehensive genetic study of Indigenous Australians to date, and it indicated that they are the oldest continuous civilisation on Earth, dating back more than 50,000 years ago.
But the results revealed something else – DNA that was very similar to that of the Denisovans, but distinct enough for the researchers to suggest that it could have come from a third, unidentified hominid.
“Who this group is we don’t know,” lead researcher Eske Willerslev told Hesman Saey.
Until we have more concrete evidence of this hypothesised third human species (some fossils would be nice), we can’t prove this, and we should point out that Bohlender’s estimates have yet to be formally peer-reviewed, so they might shift with further scrutiny.
And it could be that our identification of Denisovan DNA is more ambiguous than we think, given that our only source is a finger bone and a couple of teeth.
But the evidence is mounting that our interactions with ancient humans were far more complex than we’d assumed, which shouldn’t be much of a surprise, when you think about it.
Just because we don’t see them in the fossil record doesn’t mean they didn’t exist – preserving the remains of something for tens of thousands of years isn’t easy, and then someone has to be in the right place at the right time to dig them up.
Hopefully, the more we investigate the genetic make-up of our most ancient societies, the more hints we’ll get of the rich and complicated history our species shared with those that didn’t make it to modern times.
The results of Bohlender’s analysis were presented last week at the 2016 American Society of Human Genetics meeting in Canada.
Another interesting story from Science Alert
That Creepy Fanged Creature Washed Up in Houston Has Finally Been Identified
The Internet can stop freaking out now.
After high winds and heavy rains brought by Hurricane Harvey, a mysterious sea creature with fangs and no face washed up on the shoreline in southwest Texas – giving the Internet a challenging task: to identify it.
Preeti Desai, social media manager at the National Audubon Society, posted pictures of the critter earlier this month on Twitter, asking, “What the heck is this??”
Desai, who said she had accompanied conservationists assessing the damage from the storm, spotted the creature on a beach in Texas City, about 15 miles from Galveston.
Though the exact size was unclear, Desai told a Twitter user asking about scale that there was a drinking straw pictured next to its tail.
— Preeti Desai? (@preetalina) September 6, 2017
The Internet gave its best guesses:
A gulper eel.
A “bloated” moray eel.
No, an alien.
“I follow a lot of scientists and researchers,” Desai told BBC News about her plea for answers on social media. “There’s such a great community of these folks that are very helpful, especially when it comes to answering questions about the world or identifying animals and plants.”
She said someone suggested that she contact Kenneth Tighe, a biologist with the Smithsonian National Museum of Natural History.
Tighe, an eel expert, told Earth Touch News that the creature was most likely a fangtooth snake-eel, or Aplatophis chauliodus.
Fangtooth snake-eels live in burrows 100 to 300 feet down in waters stretching from the Gulf of Mexico to French Guiana, “with only snout and eyes exposed, darting to feed on other fishes and crustaceans,” according to FishBase, an online database for fish species.
Other possibilities? Bathyuroconger vicinus or Xenomystax congroides.
“All three of these species occur off Texas and have large fang-like teeth,” Tighe told Earth Touch News. “Too bad you can’t clearly see the tip of the tail. That would differentiate between the ophichthid and the congrids.”
Desai told BBC News that she left the dead eel alone to “let nature take its course.”
She wrote in a post Sept. 8 on Audubon’s website that in the wake of Hurricane Harvey, she traveled to Houston to help document “the effects of the hurricane on birds and their habitats.”
I joined Audubon Texas’s Coastal Conservation program manager, Victoria Vazquez, and coastal warden, Dennis Jones, to visit some of the rookery islands off the coast of Galveston and assess the damage.
They wanted to take a look at things like how much land had been lost and how much plant cover was missing due to being uprooted or washed away. Changes like these could affect the number of species that will be able to nest on the habitat in the future.
Audubon Texas and partner organisations like Houston Audubon collectively own or lease more than 170 coastal islands, some of which appear and disappear as currents shift and waves wash over them.
These islands, even when they’re no more than sandbars, are supremely important for many colonial water birds – birds that gather in groups – as they nest and breed during the spring and summer months.
Visit at the right time and you’ll find American Oystercatchers, Brown Pelicans, Least Terns, and more. (But be careful – birds are especially vulnerable during nesting season and no visitors are allowed on the islands from February through August.)
Brown Pelicans in particular were at risk of extinction in the 1970s, and although they’ve made a comeback since then, their nesting areas (and those of many other species) are now in trouble due to rising sea levels and stronger storms caused by climate change.
So it was a positive that most of the chicks had fledged by the time Harvey hit.
Still, people on social media were more interested in – and spooked by – the sea creature she stumbled upon while she was there.