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Where the Denisovans Are 2021 (LSP #206)

Where the Denisovans Are 2021 (LSP #206) August 23, 2021

Hi and welcome back! We’ve been talking about human history for a while in this series. But today’s story blows my mind. Today, Lord Snow Presides over the way one ancient human species, the Denisovans, reached the present day through our DNA.

where the denisovans were first found
Denisova Cave. (Демин Алексей Барнаул, CC-SA.)

(This week’s 1st-Century Friday topic can be found here.)

Everyone, Meet the Denisovans.

Denisovans are a long-extinct archaic human species — and a popular and intriguing new topic in the history of humankind. Their name comes from the cave in Siberia where we found the first fossils of theirs.

Denisovans lived all across Asia from 300,000 years ago to about 50,000 years ago. They were travelers and tool-makers. We’re not sure about much else about them, though. We’ve barely found any fossils at all of theirs, and few of those contain DNA to analyze.

What we do know is that Denisovans were closely related to Neanderthals. The two species shared a common ancestor, Homo heidelbergensis. One group of H. heidelbergensis left Africa around 600k-750k years ago. Of these, one group headed into West Asia and Europe and became Neanderthals. The other group headed east and became Denisovans. Meanwhile, the pre-humans who stayed in Africa evolved into us — modern humans — and won the game.

As Neanderthals interbred with humans, so did Denisovans — with one major interbreeding event taking place between 44k and 54k years ago. The Australian Museum thinks other interbreeding events took place about 30k years ago, and maybe even 15k years ago. Either way, it looks like some Denisovans were still around 30k years ago.

The Denisovans traveled quite a ways during their time on this good dark earth. But their genes may have traveled even further for even longer.

(Counting down till the Denisovans become an epic Netflix series.)

Those Denisovans Certainly Do Get A-Rooouuunnnnd.

Even if we’re not sure what Denisovans looked like (and we’re really not), we can identify their genetic code. We can tell Denisovan DNA from Neanderthal and either from our own modern human DNA.

So we now know that today’s Europeans and Asians get about 1-4% of their DNA from Denisovans. As one looks further east, people get more and more DNA from that source: Tibetans, Melanesians, and Australian Aboriginals carry 3-5% of it.

As that museum link points out, we’ve even discovered that today’s ethnic Sherpas in Tibet inherited a Denisovan gene that makes it much easier than normal for them to breathe at high altitudes. So this DNA likely serves a good purpose in those who have a lot of it.

Now, some researchers have figured out what population group we know of has the most DNA from the Denisovans.

Where the Denisovans Are: 2021.

This study was published August 12 in Current Biology, and it is just incredible. (The story about it comes to us from Science News.)

We’ve known for a while that Denisovan influence is greater in Southeast Asia than in other parts of the world. So, some researchers studied the DNA of various ethnic groups in the Philippines to see how much Denisovan DNA they had. These researchers analyzed the genetics of 1107 people from 118 ethnic groups across the Philippines, including 25 Negrito groups.

The Negrito are a large ethnic grouping of people living in Southeast Asia and the Andaman Islands. (That’s the place where John Allen Chau got killed a few years ago when he decided to go evangelize the Sentinelese without gaining their consent first.) About 30 different Negrito groups live in the Philippines.

The researchers were hoping to figure out which of these groups had the most DNA from the Denisovans.

Until now, we thought that the highlanders of Papua New Guinea held the title with 4% of it in their ancestry.

But now, focus has shifted to the Philippine Negrito people — and specifically, the Ayta Magbukon group (of Bataan, it looks like; also, that name is also spelled Magbukún Aeta) within that overall category.

These folks have 5% Denisovan DNA!

How to Get a Good Concentration of Denisovan DNA.

Considering how little of our DNA is specifically modern human DNA at all, 5% sounds like a lot.

So how did Denisovans manage to cross the vast ocean of time through the transmission of their genetic code?

Isolation, mostly, it sounds like.

Around 2200 years ago, a big influx of immigrants from East Asia arrived to the area and interbred with the people there. But the Ayta Magbukon didn’t participate to such an extent. They may have been more isolated, so didn’t interact as much in general.

Whatever the cause, the study found that Ayta Magbukon people had “roughly 30 percent to 40 percent more Denisovan ancestry than Papua New Guinea highlanders and Indigenous Australians.”

Dang.

How the Denisovans Kinda Survived After All.

Those researchers wanted to stress that we’ve only just begun to study this topic. There may be other groups whose DNA hasn’t been gathered and sequenced yet who’ll have even greater concentrations of DNA from the Denisovans — or, for that matter, from our other ancestors.

In addition, it seems to me like a lot of fossils and artifacts from the Denisovans have been discovered by accident in jumbles of uncategorized stuff that we didn’t realize was Denisovan — or even human or human-made — at all. So there might be a lot more to discover about the Denisovans that’s right under our noses.

All the same, this is one hell of a discovery, in my opinion.

More and more, we’re finding out that modern humans didn’t just bamf into existence (so to speak). We didn’t grow into our Super Saiyan final form in isolation. Other human species had a lot of influence on our development. And those other humans continue to speak to us today from our genes and the fossils and artifacts they left behind.

Today, Lord Snow Presides over all the fascinating puzzle pieces that went into making us what we are. The truth we’re discovering about our past is so much more compelling and fascinating than any myths peddled by Creationist hucksters!

NEXT UP: If someone hasn’t seen something personally, that doesn’t mean it doesn’t exist. Seems perfectly reasonable, right? But apparently, it’s not to some folks! See you soon.


1st-Century Friday Topic:

For the next 1st-CENTURY FRIDAY, we’ll be talking about a WOMAN: Pamphile of Epidaurus, a 1st-century woman who recorded historical anecdotes and (probably) wrote a famous book consisting of biographies of famous women.

As always, nobody is required to do anything. I provide this announcement only for those who want to read up on our sources ahead of time. (Back to the post!)


About Lord Snow Presides (LSP)

Lord Snow Presides is our off-topic weekly chat series. Lord Snow was my very sweet white cat. He actually knew quite a bit. Though he’s passed on, he now presides over a suggested topic for the day. Of course, please feel free to chime in with anything on your mind: there’s no official topic on these days. I’m just starting us off with something, but consider the sky the limit here. We especially welcome pet pictures!


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Just a note: Today’s post title comes from the awful sex romp comedy Where the Boys Are ’84.

Also: If you’re wondering, East Asians have the most Neanderthal DNA at 2% on average. Those of African ancestry have the least, at 0.3%.

About Captain Cassidy
Captain Cassidy grew up fervently Catholic, converted to the SBC in her teens, and became a Pentecostal shortly afterward. She even volunteered in church (choir, Sunday School) and married an aspiring preacher! But then--record scratch!--she brought everything to a screeching halt when she deconverted in her mid-20s. That was 25 years ago. Now a comfortable None, she blogs on Roll to Disbelieve about psychology, pop culture, politics, relationships, cats, gaming, and more--and where they all intersect with religion. She lives with an adored and adoring husband named Mr. Captain and a sweet, squawky orange tabby cat named Princess Bother Pretty Toes. At any given time, she's running out of bookcase space. You can read more about the author here.

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