Tuesday, March 1, 2016

Neanderthals may have used manganese dioxide for fire


Such expertise would prove a departure from current scientific understanding of the cave-dwellers' cognitive abilities. By Brooks Hays   |   March 1, 2016 at 1:06 PM

Manganese dioxide blocs collected from Neanderthal
archaeological sites in France. Photo by Leiden University/NWO

LEIDEN, Netherlands, March 1 (UPI) -- Until now, researchers assumed high concentrations of the black ore known as manganese dioxide at Neanderthal sites was explained by its use as a coloring agent in cave and body painting.
But new research suggests Neanderthals may have deliberately sourced the organic chemical for making fire.
Lab experiments conducted by a team of researchers in the Netherlands proved that the presence of manganese dioxide reduces auto-ignition temperature of wood and boosts its rate of char combustion -- making it easier to start and maintain hot and efficient fires.
As the scientists argue in their new paper on the subject -- published in the journal Scientific Reports -- regular fires would have provided Neanderthals with plenty of ash and charcoal for coloring. Collecting manganese dioxide for cave and body painting would have been redundant and an unwise use of energy.
If Neanderthals did selectively source manganese dioxide for making fire, such expertise would prove a departure from current scientific understanding of the cave-dwellers' cognitive abilities.
"We don't know how Neanderthals made fire but given their skills with lithics, we might start with an assumption they used sparks and tinder," study author Peter Heyes, a researcher at Leiden University, said in a press release. "We don't bring it out particularly in the paper but manganese dioxide added to wood shavings or other tinder increases the efficiency with which the tinder captures a spark and lights."
Using manganese dioxide for fire suggests a distinct level of sophistication with regard to Neanderthals' use of fuel.
"Finding evidence to support a view on Neanderthal management of wood fuel resources is a very remote possibility," Heyes added. "It could nevertheless have been an important aspect of subsistence. If Neanderthals could devote time and resources to collecting manganese dioxide for fire making, it is perhaps not unreasonable to assume they could manage wood fuel resources effectively."

Study of Neanderthal Y chromosome hints at fertility problems

April 7, 2016
Washington (AFP) - The first examination of a long-extinct Neanderthal's Y chromosome suggests that fertility problems may have prevented Neanderthal men from successfully mating with modern human females, researchers said.
The study in the American Journal of Human Genetics is based on a male Neanderthal whose 49,000-year-old remains were found in El Sidron, Spain.
Until now, researchers have only sequenced the DNA of female Neanderthal fossils, and have found that one to four percent of European and Asian people's DNA can be traced to Neanderthals.
But researchers at Stanford University found that the Neanderthal's Y chromosome is completely lacking in males today.
The Y chromosome is one of two human sex chromosomes (X and Y) and is passed on exclusively from father to son.
The findings suggest that Neanderthal Y chromosomes may never have been passed along when Neanderthals and humans mingled and mated some 50,000 years ago.
That could be because women may have miscarried male fetuses sired by Neanderthals, or produced very few healthy male babies that could pass on this Y-chromosome lineage.
Researchers are probing the hypothesis that modern women's immune systems might have attacked male fetuses carrying certain Neanderthal mutations.
The scientists say they found mutations in certain immune system genes from the El Sidron Neanderthal that have been blamed for transplant rejection when modern males donate organs to women.
"The functional nature of the mutations we found suggests to us that Neanderthal Y chromosome sequences may have played a role in barriers to gene flow, but we need to do experiments to demonstrate this and are working to plan these now," said senior author Carlos Bustamante, professor of biomedical data science and genetics at the Stanford University School of Medicine.
"We've never observed the Neanderthal Y chromosome DNA in any human sample ever tested," Bustamante added.
"That doesn't prove it's totally extinct, but it likely is."
Previous studies have shown that modern human and Neanderthal lineages diverged between 400,000 and 800,000 years ago.
The Neanderthals died out some 30,000 years ago.

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