Evolution: more genomic evidence of pre-planning Part One (Evolution)

by dhw, Thursday, April 08, 2021, 12:48 (1323 days ago) @ David Turell

Part One
dhw: Please stop harping on about a huge leap. Our current size is no greater than that of late erectus.'

DAVID: I'll harp as much as I can. You have offered no real proof of your position about size while studiously ignoring function.

You keep dodging from size to function. I’ll deal with function later. My point here is that there is no huge leap in size:

DAVID: Our current brain averages 1,200 cc+, so our enlargement of 200 cc is at 20% of the last size, quite a huge addition for a previous one lasting a couple millions of years.

You are talking specifically about size, you tell us that the current average is 1200 cc, and I am pointing out that erectus finished up with approx 1200 cc. I quoted three websites to support this figure.
Homo erectus Vs. Homo-Sapien: General Difference - Viva ...
https://vivadifferences.com/homo-erectus-vs-homo-sapien/
"The brain capacity was between 900 and 1200 cubic centimeters.."

DAVID: I've looked at this website. It says the largest erectus brain size reached 1,200 cc while sapiens was 1,350 cc.

Correct, and you pointed out that our current size is 1200 cc, and my point is there is no huge leap – even from 1200 to 1350. Erectus himself went from 900-1200.

DAVID: Also note the illustration of skull shape, and the small size of the frontal lobe area of erectus. You keep ignoring my point that it is the size of specific areas and their specific functional capacities that really counts.

I am not ignoring it. You keep focusing on the size of the leap, which is why I asked “how huge is huge”?

The IQ & brain size of Homo erectus | Pumpkin Person
https://pumpkinperson.com/2014/10/02/the-iq-brain-size-of-homo-erectus
“So near the end of their run, when Homo erectus averaged 1,186 cc….."

DAVID: Why did you leave out the rest of the paragraph?

Because the rest of the paragraph tells us that erectus advanced from 885 to 1,186, and it finishes up with a sapiens average of 1376 (taken from one particular group of people), which is not far off 1350. It simply confirms what I have just said. There is no “unfair play”.

dhw: And another which I referred to earlier but can’t find now:
"The upper part of the maximum estimated range for H. erectus endocranial capacity (1,200 cubic cm) thus overlaps with the lower values expected for Homo sapiens."

DAVID: I can't locate it either.

I didn’t make it up, and the point should be perfectly clear to you. There was no huge leap, so please stop insinuating that I am fiddling the figures (“unfair play”). We can now move on to function:

DAVID: This site tells the real story:
http://www.handprint.com/LS/ANC/brain.html

QUOTE: "Brain function is best inferred from the relative size and form of different brain areas. The erectus brain shows the characteristic "football" shape of hominid brains from Homo ergaster on up. This shape arises principally from a tandem expansion of the frontal (F) and occipital (back, O) lobes in relation to the rest of the brain.
"Increases in the frontal lobe appear in Australopithecus africanus and all subsequent hominid brains. This expansion signals a radical change in frontal lobe function, away from olfactory analysis toward complex abstract processing. In humans, the frontal lobes contribute heavily to social behavior and the planning of future actions.”

And there in a nutshell is your answer. Both Australopithecus africanus and erectus show expansion of the frontal lobes “toward complex abstract reasoning”.

QUOTE: "Terrence Deacon proposed that the frontal lobe is the developmental and cognitive key to human language ability. If so, frontal lobe expansion implies that hominid language abilities may be quite old, perhaps predating the toolmaking abilities that appear in stone artifacts at least 2.4 million years old. Language does not mean spoken language necessarily, but use of a syntax to interpret meaning from the order and form of two or more signs.”

Their frontal lobes expanded and performed precisely the same function as ours, even to the extent that they may have had rudimentary forms of language.

QUOTE: "The modern brain shows its greatest expansion in the middle parietal lobes (P). This expansion accounts for the rounded shape of human skulls in contrast to the flattened "football" form of skulls in earlier species, including Neandertals. Technological, abstract and computational thinking seems to arise in the parietal lobe, and this is the area of greatest relative difference between the two outlines. We might associate this parietal expansion with the appearance of remarkably diverse and refined tool cultures, and spoken language, about 90,000 years ago."

I’ll have to leave it to you experts when it comes to naming which lobe does what, but it all fits in perfectly with lobes expanding throughout history as they implement what new requirements they have to meet, initially in what for us now seem rudimentary improvements. Whatever first caused the parietal expansion in sapiens would have sufficed for his way of life until the wave of new ideas and requirements resulted in enhanced complexification 90,000 years ago, and subsequently this proved so efficient that 150 cc of previously essential cells became redundant. (Contd. in Part Two)