Innovation and Speciation: fire and brain size (Evolution)

by David Turell , Tuesday, June 20, 2017, 00:36 (2712 days ago) @ David Turell

The studies are still trying to find when humans first used fire which greatly increased the caloric consumption needed for the biggest brain of all in H. sapiens, which needs 20% of daily calories if used very actively:

https://www.scientificamerican.com/article/quest-for-clues-to-humanitys-first-fires/?WT...

"Her question is a basic one about a crucial early technology: When did humankind first put fire to work for them, using it regularly for heat and cooking? Hlubik and other archaeologists who sift through the long-cold ashes of fires past cannot say for sure. It probably wasn’t as early as 2 million years ago—but it almost certainly occurred by 300,000 years ago. That leaves a big gap, with plenty to investigate.

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"The question gets at the very root of what it means to be human: Fire is one of the things that pushed human evolution along. Roasting foodstuffs meant a calorie-rich diet, which may have fueled our big brains into existence. Fire provides protection from predators and a warmth that may have allowed humankind to extend its geographical reach. Plus, tending a blaze and gathering around it could have helped shape us into the social animals we are now. Understanding when people mastered fire could help archaeologists figure out if and how it contributed to these major events in the evolution of the human body and mind. For example, did it really coincide with a jump in brain size, which would indicate it may have helped make us deep thinkers? (my bold)

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"But pinning down “regular use” is a hard task. One of the earliest sites with evidence of persistent fire use is Qesem Cave in Israel, which hominins started using about 400,000 years ago. “The cave is full of wood ash,” says Ran Barkai, an archaeologist at Tel Aviv University in Israel. “We have tons of burned bones and burned flint items.” He believes the inhabitants were capable of lighting fires, though he does not yet have direct archaeological evidence of that. But even at Qesem, it’s hard to be sure if the cave users gathered around fires often, or only harvested a rare one once a century, notes Sandgathe; dating methods simply aren’t precise enough to tell.

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"Regardless of when exactly humankind managed to make fire a regular presence in their lives, scientists agree it was a turning point in human evolution. Eventually, humankind hit a point of no return when fire became essential. Modern humans can’t do without it, whether to burn gasoline in our engines, warm our nearly hairless bodies, or cook porridge or steak.

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"Earlier hominins, of course, reproduced just fine in the cold. Wrangham suggests that the situation began to change with Homo erectus, who probably arrived on the scene about 1.9 million years ago. Its ancestors had big teeth to crush tough foodstuffs, large bellies to ferment those meals, and relatively small craniums. With Homo erectus, scientists see a shift to a taller and brainier hominin who spread across Africa, into Asia, and throughout parts of Europe. “What was it that made Homo erectus possible?” asks Hlubik. “There had to be something that happened.”

"That something, she and Wrangham think, could have been fire control. The early fire dates creeping up on 2 million years ago could support that hypothesis, but other archaeologists say the evidence on the ground is thin.

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"While calorie-rich meals might have been a main driver for the adoption of fire, there are other benefits, from warmth to protection from predators. Tending a hearth also could have made a big difference in the evolution of social skills: People would have had to cooperate to manage and feed fires, and they perhaps socialized around the flames. “When you bring fire into a habitation, I think something pretty profound happens,” says Chazan. “It’s mesmerizing.'”

Comment: Note that fire appears to be related to larger brains: how to control it and also, at the same time, how to feed a bigger brain. There is no getting around the fact that with larger brains hominins found better ways to support. With each size better ways. Size first use second, always.