Wednesday, August 29, 2018

Neandertal/Denisovan Hybrid?

As J. Lawrence Angel once said: “When two groups of people meet, they may fight, but they will always mate.”  A story is now coming out of Russia describing more research at the Denisova Cave, in the Altai Mountain region that recounts exactly what Angel was talking about.  From Richard Coniff, at Scientific American:
In a remarkable twist in the story line of early human evolution, scientists have announced the discovery of “Denisova 11”—a female who was at least 13 years old, lived more than 50,000 years ago and was a child of mixed parentage. Her parents were not just of different races, but two different and now-extinct early human types. Their exact taxonomic designations—whether they were separate species or subspecies—is still a matter of scientific debate. But the bottom line for Denisova 11 is that mom was a Neandertal and dad a Denisovan.
This is a remarkable claim, similar to the one that Erik Trinkaus made about the Lagar Velho child discovered in Portugal that is thought to be a Neandertal/modern human offspring. What evidence has been marshalled to support this claim?  In a word: genetics.  The evidence is taken from another bone fragment from the site.  From the abstract:
The father, whose genome bears traces of Neanderthal ancestry, came from a population related to a later Denisovan found in the cave. The mother came from a population more closely related to Neanderthals who lived later in Europe than to an earlier Neanderthal found in Denisova Cave, suggesting that migrations of Neanderthals between eastern and western Eurasia occurred sometime after 120,000 years ago. The finding of a first-generation Neanderthal–Denisovan offspring among the small number of archaic specimens sequenced to date suggests that mixing between Late Pleistocene hominin groups was common when they met.
So, if they interbred regularly (or regularly enough, anyway), why aren't they just one species?  Svante Paabo argues that it is because they simply did not come together very often.  To this, I would argue that they probably also had fairly distinct cultures. 

If this kind of information had come out a few decades back, there would have been quite a few squawks and naysayers but as the evidence piles up for hybridization between many different groups throughout the Pleistocene, researchers have become more accepting of it.  It is pretty clear that the evolutionary picture was a whole lot more complex than we thought. 

Tuesday, August 28, 2018

More Evidence of Complex Tool Creation By Archaic Homo sapiens

New excavations at Boxgrove, a site which dates from approximately 300 thousand years ago has yielded tools that show more complex creation strategies.  From the Independent:
The specific stone tools which were analysed as part of the study were sophisticated flint hand axes, which had required a special technique to shape them.

The technique is known to prehistorians as ‘platform preparation’. In most very early stone tools, the manufacturing process is a simple single-stage affair in which the toolmaker merely hits a lump of flint with a stone repeatedly to systematically knock bits off it until the lump has been reduced to a desired shape.

However, more sophisticated toolmakers employed a two-stage approach. First they would successively "soften up" small portions of the flint’s surface, so as to then be able to more accurately remove flakes from it, thus creating a much more sophisticated and effective tool with a better and more refined cutting edge.
Quite a bit of evidence is emerging that the group of hominins loosely called “archaic Homo sapiens” was considerably more technologically and socially advanced than we once thought. Whether or not they looked modern, they were beginning to act that way. 

Monday, August 13, 2018

Homo erectus Was Lazy??

A short piece in PhysOrg links to an article in PLoS that argues that, when faced with the opportunity to make Acheulean tools out of really good raw materials at a site in what is now Saudi Arabia, the local Homo erectus group took the easy way out and made them out of whatever was lying around.  From the PhysOrg piece: “New archaeological research from The Australian National University (ANU) has found that Homo erectus, an extinct species of primitive humans, went extinct in part because they were 'lazy'.”

First off, the first paragraph is nothing short of idiotic. There is absolutely no evidence whatsoever that Homo erectus went extinct because they were lazy. They colonized huge sections of Asia and were integral to the appearance of early modern humans in the area.They might have disappeared from this particular area of Saudi Arabia but that is all.  Also from PhysOrg:
"At the site we looked at there was a big rocky outcrop of quality stone just a short distance away up a small hill.

"But rather than walk up the hill they would just use whatever bits had rolled down and were lying at the bottom.

"When we looked at the rocky outcrop there were no signs of any activity, no artefacts and no quarrying of the stone.

"They knew it was there, but because they had enough adequate resources they seem to have thought, 'why bother?'".

This is in contrast to the stone tool makers of later periods, including early Homo sapiens and Neanderthals, who were climbing mountains to find good quality stone and transporting it over long distances.
Maybe this particular population was stressed in some way. Maybe the tools that they made were good enough to get done what they needed. Who knows. It is a huge inference, though, that because they didn't use the raw materials that were better that they were “lazy.”  The last sentence of the abstract reads thus:
The Acheulean hominins at Dawadmi were strong and skilful, with their adaptation evidently successful for some time. However, these biface-makers were also technologically conservative, and used least-effort strategies of resource procurement and tool transport. Ultimately, central Arabia was depopulated, likely in the face of environmental deterioration in the form of increasing aridity.
This sentence alone belies the opening, “lazy” paragraph of the PhysOrg story.  More junk journalism. 

Monday, August 06, 2018

Dear Arizona Residents: Vote For Jonathan Gelbart

AZ Central is reporting that of the five GOP candidates running for superintendent of schools, four of them support the teaching of creationism and intelligent design in public schools.  Ricardo Cano writes:
Jonathan Gelbart was the sole Republican candidate who opposed teaching students creationism and intelligent design. He is joined by Democrats Kathy Hoffman and David Schapira.

The four others — Bob Branch, Frank Riggs, Tracy Livingston and incumbent Diane Douglas — each said they believed students should be taught those topics in some capacity.

The state will likely decide on new science standards later this year.
Republican candidates were asked by moderator and Republic reporter Richard Ruelas whether they were in favor of teaching accepted science, including climate change and evolution.

The question morphed into a broader discussion over the teachings of creationism and intelligent design in Arizona public schools.

Gelbart, 29, a former director of charter development for BASIS.ed, touted that he is the only Republican candidate to say that he "absolutely (does) not support" including the teachings of creationism and intelligent design as part of the science standards they are required to learn.

"It's not science," Gelbart said.

Branch, 60, a professor and Maricopa County Parks and Recreation commissioner, is running on a pro-President Trump platform, emphasizing Christian conservative values.

His stance contrasted Gelbart's.

“I believe in intelligent design — I don’t believe it’s mutually exclusive from evolution," Branch said. "I believe that there is a science behind intelligent design, so where Mr. Gelbart said science should be left to science, I believe in the science of intelligent design.”
And therein lies the problem. You don't “believe” in any part of science. I doubt seriously that most of these GOP candidates, if asked what the basic tenets of biological evolution are, would be able to respond coherently.Other candidates speak of teaching "both sides" and "strengths and weaknesses" as though there are two sides.  In 150 years, no one has been able to promote a competing theory to biological evolution. All attempts to do so have failed and detractors are reduced to trying to find holes in the theory.  As I have written before, all candidates for school boards should have to pass a test in basic science literacy.  Rarely do I think that a federal solution is the answer but sometimes I wonder about this.