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Northern Paladin
Monday, May 1st, 2006, 05:34 AM
Why has the trend for the last 30,000 years been for smaller brains. Why is it that despite this we are getting more intelligent?

Bridie
Monday, May 1st, 2006, 05:54 AM
It's not the size of the brain that denotes intelligence.... its the surface area of the outer layer of the brain, the grey matter, that counts. :) Surface area is increased by frequency and depth of convolutions of the brain. (N.B. although women have smaller brains than men, they have often a larger surface area of grey matter, due to having more and deeper convolutions!! :D Hehe)

Smaller heads may be a naturally selected feature due to the decreased likelihood of the mother of smaller headed babies dying in natural childbirth. Of course, this isn't so much of an issue nowadays with modern medical intervention.

Bioblitzkrieg
Monday, May 1st, 2006, 05:55 AM
I dont know the specific facts to back this up, but ive heard that the brain size alone isnt so much the thing to focus on as is the size of the brain/braincase in ratio to the rest of the body. So as the brains in modern humans may be losing some mass, so is the robustness of the skull and skeletal structure, keeping equal or perhaps even increasing the mass of the brain in percentage to the rest of the body, but physically still taking up less space as the size of our physiques are in general becoming less robust.

I could be wrong, lets hear some more minds at work.

Northern Paladin
Monday, May 1st, 2006, 06:03 AM
It's not the size of the brain that denotes intelligence.... its the surface area of the outer layer of the brain, the grey matter, that counts. :) Surface area is increased by frequency and depth of convolutions of the brain. (N.B. although women have smaller brains than men, they have often a larger surface area of grey matter, due to having more and deeper convolutions!! :D Hehe)

Smaller heads may be a naturally selected feature due to the decreased likelihood of the mother of smaller headed babies dying in natural childbirth. Of course, this isn't so much of an issue nowadays with modern medical intervention.

I think that's a very likely explanation. And it would also seem that having too big of a head would prove to be too much of a balancing act for a bipedal animal like oursevles.

And perhaps we are as smart as we need to be right now.

Scientists generally agree that women and men are close to the same in intelligence. However there is also much evidence to support the fact that women and men are good at different things. And this is a direct reflection of brain structure.

Dr. Solar Wolff
Monday, May 1st, 2006, 08:25 AM
The disadvantage of inheriting a large brain is the box it comes in. It is very hard for the mother to push a large head through the birth canal. Some study somewhere reported that a baby's IQ could be linked positively to the spread of his mother's pelvis. Cranial capacity is linked to IQ but that is not the only factor in IQ.

Let's face it folks, it doesn't take a big brain or a high IQ to survive and reproduce today. There is probably very little survival value in our society for high IQ or a big brain.

Heglameister
Monday, May 1st, 2006, 09:30 AM
There could be a number of reasons. Modern technology doesn't require us to think as much. Humaniods brain size dramatically increased with increased meat consumption. People are eating less meat these days. Use it or lose it? In pre-civilization days, humans survival depended on his/her ability to think and resolve problems. Today people live whether they think or not as long as thery eat. Very good question. It could also be a statistical issue depending on the source of donor brains that have been measured.

Nixie
Thursday, August 10th, 2006, 07:37 AM
Intelligence also has more to do with what percentage of the brain is utilized. A massive brain with superhuman potential is worthless if the owner can only activate 5% of it. Even though we supposedly only use 10% of our current brain potential, maybe that's more than has been used in times past. So we don't need to get bigger at all.
Or, alternatively, humans used to use a greater percentage of brain, but it has steadily declined to 10% and evolution is finally doing something about it by gradually getting rid of the excess we no longer use. Maybe we have failed to live up to the optimism of nature/the gods implicit in our large brains.

Ragnar Thorsson
Thursday, August 10th, 2006, 09:34 PM
Why Are Human Brains Getting Smaller?

It's the beer!:thumbup :D

Agrippa
Thursday, August 10th, 2006, 10:09 PM
Negative-, contraselection which led to physical and psychic degeneration.

There were various heights, peaks of positive biological development like in the Mesolithicum, late Neolithicum, Bronze Age and Iron Age in Europe, especially under more mobile, well fed and warlike people like successful hunter-gatherers, half-nomadic mixed farmer groups and herders and periods of downgrading, like we can see it today in modern Liberalcapitalistic societies.

High energy input and high group selective pressure = Higher general potential
Low energy input and low group selective pressure = Lower general potential - possibly degeneration.

Klegutati
Thursday, August 10th, 2006, 11:38 PM
Maybe there is a link between the Y-chromosomem and the side of the brain. For men are getting smarter but the Y-chromosome is getting smaller.. HAHA:D :thumbup