Read moreAround 50,000 years ago, there is widespread evidence of producing bone and antler tools, heat-treated and flaked flint, projectile weapons, grindstones, fishing and birding equipment and a command of fire.
“Was this driven by a brain mutation, cooked foods, the advent of language or just population density?”
Dr Hare and his colleagues argue that human society advanced when people started being nicer to each other, which entails having a little less testosterone in action.
“If prehistoric people began living closer together and passing down new technologies, they’d have to be tolerant of each other. The key to our success is the ability to cooperate and get along and learn from one another,” said Robert Cieri, a student at the University of Utah and the first author on the study published in the journal Current Anthropology.
In their study, the scientists compared the brow ridge, facial shape and interior volume of 13 modern human skulls older than 80,000 years, 41 skulls from 10,000 to 38,000 years ago, and a global sample of 1,367 20th century skulls from 30 different ethnic populations.
The trend that emerged was toward a reduction in the brow ridge and a shortening of the upper face, traits which generally reflect a reduction in the action of testosterone.
“Heavy brows were out, rounder heads were in, and those changes can be traced directly to testosterone levels acting on the skeleton,” said Prof Steven Churchill of Duke University, a co-author on the study.
technology
Read moreBut based on evidence from ancient bones, spears, and porridge, Speth believes our Stone Age cousins likely boiled their food. He suggests that Neanderthals boiled using only a skin bag or a birch bark tray by relying on a trick of chemistry: Water will boil at a temperature below the ignition point of almost any container, even flammable bark or hides…
Speth suggests that Neanderthals boiled foods in birch bark twisted into trays, a technology that prehistoric people used to boil maple syrup from tree sap.
Archaeologists have demonstrated that Neanderthals relied on birch tar as an adhesive for hafting spear points as long as 200,000 years ago. Making birch tar requires clever cooking in an oxygen-free container, says paleontologist Michael Bisson of Canada’s McGill University.
“I’ve burned myself trying to do it,” Bisson says, adding that Neanderthals were plenty clever when it came to manipulating birch. They likely ignited rolled-up birch bark “cigars” and plunged them into holes to cook the tar in an oxygen-free environment.
If the tar is exposed to oxygen in the air as it cooks, “it explodes,” Bisson adds.
Supporting the boiling idea, Speth said that animal bones found in Neanderthal settings are 98 percent free of scavenger’s gnawing marks, which he says suggests the fat had been cooked off.
And some grains found in the teeth of a Neanderthal buried in Iraq’s Shanidar Cave site appear to have been cooked, according to a 2011 Proceedings of the National Academies of Science report.
“It is speculative, but I think it is pretty likely that they knew how to boil,” Speth says.
In a separate talk at the meeting, University of Michigan paleontologist Andrew White noted recent evidence that Neanderthal mothers weaned their children at an earlier age than human mothers typically do. He said the early transition from milk to food supports the theory that Neanderthals boiled their youngsters’ food to make it more digestible.
The Committee to Nuke Elysium 