AS A SPECIES, WE ARE EVOLVING SMALLER BRAINS

Anyone seen my cap?

Interesting. I have no worthwhile comment.

I don't find that surprising; humans are able to learn from previous learnings, and build from there. Our ability to build instruments that helps us research many aspects of our environment is nothing short of miraculous!

The size of computer chips becomes smaller while increasing memory and getting faster.

I'm not where all this is going to lead humanity, but I suspect that China will be the leader of this world in the future.

There's an interesting article in today's San Jose Mercury News about Chinese students from China growing in the US, but especially in California. Students from China pay full tuition, so most of the universities encourage and try to recruit more students from China. Many American students resent it, because the Chinese students come prepared, and do better in math and science courses.

I don't see that slowing down any time soon, and that will give them the advantage in all aspects of the world economy.
I just wonder when China will over-take the US as the economic superpower. It's only a matter of time.

I wrote that in haste. My phone was ringing and I got distracted before hitting the submit button.

What I meant to say is that they need to devise some way to differentiate between the actual evolving of a trait (smaller brain) due to selection, and the possibility that brains naturally get smaller with each generation UNLESS there is a selective factor actively countering that effect.

Somewhat like the evolution of computer chips.

I'm finding the 20,000-30,000 years ago turning point interesting - a possible environmental change? It's getting toward the end of the paleolithic period (and the pleistocene glaciations), but still over 10,000 years before agriculture. Is it possible that the human brain got a little more efficient in terms of energy requirements?

Are the authors including corrections for the ratio between body size and brain size? Generally the ratio stays the same, so our expanding bodies have expanding brains by default.

Another thing to consider is that turning point is pretty close to the extinction of the neanderthals, that had a larger brain than homo sapiens - perhaps a shrinkage indicates a watering down of neanderthal genetic traits?

One problem in attempting to attribute this to natural selection is that it is not clear that the mere size of the brain is an important factor. Homo Neanderthalis and Cro Magnon both had larger brains than we do now. In the case of the Neanderthals, although they were definitely clever (current archaeological evidence is that they were the first to come up with the technique of using iron pyrite and flints to make fire), what appears to have been their eventual downfall was the lack of variety in their diet. Israeli archaeologists have found a site which was first settled by early modern man, and subsequently Neanderthal moved into the same area, with both groups living side by side. The early modern man middens show a wide range of forage foods, as well as game and fish, while the Neanderthal middenns show a heavy realiance on game animals, far less forage food, and very little fish. It seems the Neanderthal were eventually condemned by the limited diet which did not allow them to compete effectively in the same environment with early modern man.

I don't think the physical size of the brain was that important. Apart from those considerations, a great deal of the brain tissue is used for redundancy of memory and function. You wouldn't necessarily be losing efficiency by a reduced mass.

Homo sapiens Idaltu had the biggest of cranial capacity of our immediate species and it was apparently all frontal lobe size. The idaltu crania hd two noticeable buklges in front and this transferred into the larger capacity (almost 1400 cc). The neandertahls had most of their cranial capacity (avg 1450 cc ) in their "back bulge", this was probably a bulk compensation but was not anything that reflcted cognative abilities. Our "shrinking" brain is all in the frontal (cognative) lobes, including optical.
My question is, since 100 cc is about as big as a hand ball (3.5 liquid oz) can that spatial decline result from things like eyeglasses and not any decline in cognative skills??

As i said, i've read that much of the brain tissue is used redundantly, to store memory and to take over function in the event of injury to other portions. So i am skeptical toward the notion that we can even determine if any cognitive abilities are lost through this "shrinkage."

By the way, i think Roswell has a good point about our not knowing what selective functions are in play here.

Ill bet, if we put our heads together we could come upwith some outrageous and neat experiment to test this. Lest just keep doing random Scans of living heads and instead of selecting, randonly grb subjects from all types of civilizations
I wanna submit one Just because we cant seem to discern what the selective aspect or advantage is, Im sure that, with continued studies it will be obvious, just like reinforced ALleles of the STR types, where every civilization imparts a special gene compliment.

The only problem will be to get past the PC police.

Id like to test whether , by this method, we could see the brain cap[acity to be affected by being a"generalist" where everyone, has to be well trained in most all needed skills to survive, (eg looking at native and remote innuits and laps etc) then compare that to statistically normatized brain capacities of industrialized country folks.
It wopuld all have to be made with some degree of rigor. Wed have to compare key bone sizes to the brain sizes and body organs etc, because its proportionally relative to the overall mass of the body.
florensis was either a microcephalic dwarf or was a true small person like a smaller pygmy (Definition had been any bodysize in which the adult is less than 4.2 Ft tall) and its branial capacity was still proportionately smaller than ours so hes an outlier already.

Clues to the evolution of humans' large brain
http://genome.wellcome.ac.uk/doc_WTD020880.html

You mean if we cram our little bitty brains together into one big brain we might be able to figure this out

The human brain is already an amazing piece of biology; people who have had brain surgery of removing some of the brain from one side, the other side will take over their function. I'm not sure how to relate this to evolution, but that's been the case for many with brain surgery.

That's a good point. Especially with illiterate cultures.

brain size might be getting smaller, but not skull size! i think any woman who has given birth can attest to that! so, why are skulls gettting bigger and brains smaller?

Maybe that's the answer: diets have changed dramatically that have resulted in bigger humans while the brain remained the same size.

I came to this conclusion from the fact that when I was a child, most Japanese (even Americans) were of small stature compared to their caucasian counterparts. As the diets changed for Japanese Americans, we started to get taller. Back during WWII, most Japanese American men were about 5' 3".

I'm now 5' 7"; I believe it had to do with our diet.

The way you eat, Im not surprised that youre still growing

farmerman, With age, I'm now in the shrinking stage.

youre not shrinking, youre "settling"