Evolution and humans: big brain size or use. size (Evolution)

by David Turell @, Tuesday, May 30, 2017, 01:08 (750 days ago) @ David Turell

I think it should be clear that when a 200cc increase in size is mentioned, what that means should be visualized. The increase is roughly equivalent to a seven ounce glass of water. That is a big jump in brain volume. It doesn't reveal if complexity or density are increased in the newly enlarged brain, but its evolution involves coordination with skull growth to accommodate the new volume. Not a simple process.

We became civilized only 10,000 years ago as agriculture appeared and then intense civilization brought enormous uses of the brain. But our brain is slightly smaller in recent years. A current study looks at stone age shaping of stone tools at two ages and guesses at brain responses by looking at current subjects producing the stone tools:


"By using highly advanced brain imaging technology to observe modern humans crafting ancient tools, an Indiana University neuroarchaeologist has found evidence that human-like ways of thinking may have emerged as early as 1.8 million years ago.

"The results, reported May 8 in the journal Nature Human Behavior, place the appearance of human-like cognition at the emergence of Homo erectus, an early apelike species of human first found in Africa whose evolution predates Neanderthals by nearly 600,000 years.

"'This is a significant result because it's commonly thought our most modern forms of cognition only appeared very recently in terms of human evolutionary history," said Shelby S. Putt, a postdoctoral researcher with The Stone Age Institute at Indiana University, who is first author on the study. "But these results suggest the transition from apelike to humanlike ways of thinking and behaving arose surprisingly early."

"The study's conclusions are based upon brain activity in modern individuals taught to create two types of ancient tools: simple Oldowan-era "flake tools" -- little more than broken rocks with a jagged edge -- and more complicated Acheulian-era hand axes, which resemble a large arrowhead. Both are formed by smashing rocks together using a process known as "flintknapping.'"

"Oldowan tools, which first appeared about 2.6 million years ago, are among the earliest used by humanity's ancestors. Acheulian-era tool use dates from 1.8 million to 100,000 years ago.


"The resulting brain scans revealed that visual attention and motor control were required to create the simpler Oldowan tools. A much larger portion of the brain was engaged in the creation of the more complex Acheulian tools, including regions of the brain associated with the integration of visual, auditory and sensorimotor information; the guidance of visual working memory; and higher-order action planning.

"'The fact that these more advanced forms of cognition were required to create Acheulean hand axes -- but not simpler Oldowan tools -- means the date for this more humanlike type of cognition can be pushed back to at least 1.8 million years ago, the earliest these tools are found in the archaeological record," Putt said. "Strikingly, these parts of the brain are the same areas engaged in modern activities like playing the piano.'"

Comment: H. erectus had a brain size of 900cc, and is showing development of an advancing human use of the brain at 1.8 million years ago. But Lucy is 3 million years ago at 400cc and the Oldowan tools did not require much brain activity at 2.8 million years ago and were made by H. habilis, who preceded H. erectus. Habilis brain size was 640cc. The brain was simply used until recently, and intensely in the past 10,000 years, but is slightly smaller. Based on the adolescent brain study quoted earlier, I would guess our brain is becoming more dense. Size first use second.

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