Tuesday, March 20, 2018

Modern Humans Interbred with Two Groups of Denisovans

There is now more evidence that were were “one big happy family.”  Here is a short recap:
Beginning around 1.8 million years ago, a hominin form called Homo erectus left Africa for points east, eventually settling in Indonesia and China. These early humans were characterized by having heads roughly ¾ the size of modern humans with very large brow ridges and with their widest point just above the ears. They were also the first humans to conquer fire and perfect hunting.
Then, at some point, between 300 and 500 thousand years ago, a population group migrated from North Africa into Europe and, eventually into East Asia. The European branch became the Neandertals, between 200 and 250 thousand years ago, and the East Asian group eventually became the Denisovans. The Denisovans then spread east and south, eventually mixing with other populations, some of which were the precursors of the Melanesians and native Australians. The bulk of the Neandertals hunkered down in Europe and tried to outlast the bitter cold of not one but two glaciations.  Despite this, while often pilloried in cultural literature as being half-witted brutes, Neandertals were a very complex society, with advanced weaponry and hunting behavior, grave goods, habitation structures and who practiced ritual behavior. Some populations of Neandertals eventually  expanded their range into Western Asia and steppic Russia and interbred with the Denisovans.  Unfortunately, as a culture, we know next to nothing about the Denisovans. 
Roughly 100 thousand years after this, there was yet another wave of migration, between 100 and 60 thousand years ago, of early modern humans from North Africa, who moved north and East mixing with both the Neandertals in Europe and, perhaps, Western Asia and the Denisovans in East Asia.
And now we learn that the modern humans arriving from Africa interbred with not one but two groups of Denisovans.  From Gizmodo:
We know so little about the Denisovans that they don’t even have a formal scientific name, though scientists are considering Homo sp. Altai or Homo sapiens ssp. Denisova. Indeed, as these names suggest, Denisovans were a branch of humans, having diverged from Neanderthals some 200,000 years ago. We know this because the Altai fossil yielded a near-complete genome, which scientists have been poring over since it was first sequenced in 2010.

But in addition to the Neanderthal ancestry, genetic anthropologists also learned that Denisovan DNA lives on in modern humans, especially among Oceanians and East and South Asians. This means anatomically modern humans, or Homo sapiens, must’ve interbred with a population of Denisovans. But as new research published today in the science journal Cell points out, our ancestors mated with Denisovans on at least two different historical occasions. So the traces of Denisovan DNA embedded in the genomes of some people living today originated from at least two distinct Denisovan populations.
Given Palaeolithic population densities, this is not surprising.The research seems to indicate that there were early modern human/Denisovan mixes in both Asia and Oceania.  What this means is that, once the Denisovans and Neandertals split, the Denisovans migrated east and northeast (as humans will do) and established population centers in these areas.  When the modern humans came (Huh.  I wonder what is over that hill?  Oh look, humans...sort of.) it made sense to intermingle with them.  We already know that Neandertals and modern humans could, and did, mix.  It is, absent any knowledge to the contrary, reasonable to assume that the Denisovans looked mostly modern human. 

Interestingly, the research seems to indicate that the rate of interbreeding of Neandertals to early moderns was much more limited than with moderns and Denisovans.  This is at variance with other studies (and fossil material) which seems to indicate more sustained contact.  It would be nice if we could find a bit more fossil evidence to get a handle on what at least one Denisovan looked like. 

Saturday, March 10, 2018

Human Evolution, Walking and FoxP1

The Smithsonian has an interesting article on hox genes and how a discovery may inform about how walking came about:
What does a mouse have in common with a cartilaginous fish known as a little skate?

At first glance, you might think not much. One’s fluffy, with big ears and whiskers; the other breathes with gills and ripples its way around the ocean. One is a lab animal or household pest; the other is most likely to be seen in the wild, or the bottom of a shallow pool at an aquarium. But it turns out these two vertebrates have something crucial in common: the ability to walk. And the reason why could change the way we think about the evolution of walking in land animals—including humans.

A new genetic study from scientists at New York University reveals something surprising: Like mice, little skates possess the genetic blueprint that allows for the right-left alternation pattern of locomotion that four-legged land animals use. Those genes were passed down from a common ancestor that lived 420 million years ago, long before the first vertebrates ever crawled from sea to shore.
According to the story, when the researchers removed the FoxP1 gene (short for Forkhead Box P1) from the skates, they couldn't walk.  Further analysis revealed that the same thing happened to mice.  They simply lost the ability to coordinate their legs.  They couldn't walk.  This research suggests that the gene that allows us to do the simple act of walking originated over 400 million years ago.  Neat stuff.

Friday, March 09, 2018

Daniel Everett: Homo erectus Could Speak and Make Boats

Bentley University Global Studies professor Daniel Everett argues that Homo erectus could speak and had the ability to make ocean-going vessels.  The Guardian has the story:
“Oceans were never a barrier to the travels of Erectus. He travelled all over the world, travelled to the island of Flores, across one of the greatest ocean currents in the world,” said Daniel Everett, professor of global studies at Bentley University, and author of How Language Began. “They sailed to the island of Crete and various other islands. It was intentional: they needed craft and they needed to take groups of twenty or so at least to get to those places.”

While Everett is not the first to raise the controversial possibility that
H. erectus might have fashioned some sort of seagoing vessel, he believes that such capabilities mean that H. erectus must also have had another skill: language.

Erectus needed language when they were sailing to the island of Flores. They couldn’t have simply caught a ride on a floating log because then they would have been washed out to sea when they hit the current,” said Everett, presenting his thesis at the meeting of the American Association for the Advancement of Science in Austin. “They needed to be able to paddle. And if they paddled they needed to be able to say ‘paddle there’ or ‘don’t paddle.’ You need communication with symbols not just grunts.”
It is pretty clear that Homo erectus hunted, at least in some fashion, could control fire and evidence seems to be accumulating that they hafted spears and, at least late in the range, the European variant set up rudimentary complex settlements.

There is, naturally, skepticism that any hominin form prior to Neandertals were sea-going: 
But others say that there is little evidence that H. erectus was a sophisticated seafarer, let alone had a language. “I don’t accept that, for example, [Homo] erectus must have had boats to get to Flores,” said Chris Stringer, head of human origins at the Natural History Museum in London. “Tsunamis could have moved early humans on rafts of vegetation.”
Before dismissing that idea out of hand, remember that it is the best one going to explain how the New World Monkeys got where they are, since Africa and South America had parted ways some 180 million years prior to their arrival.

I think there is likely not enough evidence to know one way or another if Homo erectus could sail the high seas and had speech, although the only skeletal evidence that we have for that part of the anatomy suggests not. 

Thursday, March 08, 2018

A Mistake Rectified

I have been extraordinarily busy the last few weeks and had hoped to post about this at the time.  Ken Ham was invited to speak at the University of Central Oklahoma.  I have no sympathy for anything that Ken Ham either writes or speaks but what happened next was appalling.  After the invitation, pressure was put on the UCO student association by LBGT groups to disinvite him.  LGBT people make up (charitably) 5% of any given population.  Nonetheless, the UCO group in charge, in what is coming to be the typical, spineless response, rolled over and acceded to their demands.  According to school officials this was done independently of campus administration:
“The university may advise, but does not direct, the activities of [University of Central Oklahoma Student Association],” Johnson wrote. “In fact, in the spirit of the UCO policy on freedom of expression, the university President, Provost and the Vice President of Student Affairs supported and did not deny the proposal to bring Mr. Ham to campus to encourage conversation and debate of diverse perspectives. This was prior to UCOSA’s cancellation of the invitation to Mr. Ham.”
More information came out by way of student association president, Stockton Duvall:
He also said he had been bullied by “a very vocal group on campus that has little tolerance for opposing viewpoints.” Duvall did not specifically cite LGBT activists in his memo.
But according to emails obtained by Todd Starnes of Fox News, LGBT activists played a role.
“We are currently getting bombarded with complaints from our LGBT community about Ken Ham speaking on our campus,” Duvall wrote in an email to Answers in Genesis.
This ought to be simple. If you don't like what the speaker is saying, don't go.  It has been an interesting study in cultural norms to watch the LGBT community go from asking for tolerance to demanding tolerance to, now, demanding endorsement of their views and behaviors.  As far as they are concerned, it is now no longer okay to have a view that doesn't fit with the gay agenda and people who's views don't align shouldn't be allowed to speak. That the student government association obliged them is disgraceful.

But then this happened:
The University of Central Oklahoma (UCO) has decided to re-invite Christian creationist Ken Ham to present his views at the institution, after he was dis-invited last week.

The decision has been celebrated by some on the campus as a step forward for 'free speech', according to KOKO News 5. Ham's perhaps surprising re-invitation stands out in UK and US student culture, where the 'no-platforming' of controversial speakers has become more common.
Kudos to pastor Paul Blair of Fairview Baptist Church for leading the charge to get Ham re-invited. As much as I don't agree with Ham, I have no patience or sympathy with liberal fascism or bullies.