When I was in high school, I was taught that in the past, childbirth was very difficult because babies have big heads which is necessary for “intelligence”
The argument was that the evolutionary benefit of greater intelligence was “worth” the increased danger to mother and child in childbirth.
Seems reasonable, but is it true?
I mean, men have bigger heads than women, but men aren’t more intelligent, are they? Does the extra capacity go for parallel parking ability? And what about elephants – they have big heads.
Would it make childbirth easier for babies to have smaller heads? Why not then . . . .
In proportion to the rest of the body, a baby’s head is big. However, the size of the brain is not the determining factor for intelligence. Different species have more convolutions of the gray matter, and the more convolutions the larger the actual cortex of the brain. Elephants’ brains, I believe, are bigger than ours, but their brains don’t have as many convolutions, which increases the actual surface area of the brain.
Also, the actual size of the brain does not determine actual intelligence. Some geniuses have been reputed to have had small brains compared to idiots. The neuronal growth and connections inside the brain is important.
I don’t think it has alot to do with size. Up to a specific point.
Elephants have larger brains, but that is mostly due to nerves and motor control mechanisms. Larger surface area= more brain needed.
As far as humans go, It would seem that our ancestors had much smaller brains, but then again, I am not too certain on the size of said ancestors. (Judging from the size of the skulls in this link, not very big)
Barbitu8 is correct about the convultions of the brain. Rats in tests have shown that in an enriched enviroment, the actual density of the brain increases as it gains more convultions. Indicating that as you learn, more convultions are added.(seemingly indicating anyhow). I will try to find a link if I can, or the name of the book I read this in.
There was a great article on this waaaaay back in the early '80s in Isaac Asimov’s Science Fiction Magazine, by Tom Rainbow (PS lost my copy of it, if anybody has one and would be willing to photocopy the article for me I’d be eternally grateful). Basically, what determines intelligence is (or at least one theory of it) is the ratio of neurons to body mass. The bigger the body mass, the more neurons it takes to manage it and the more neurons you have, the bigger your body can be, or the greater your intelligence can be. An elephant has the same amount (roughly) of neurons in its brain, as a human does, but an elephant has a much larger body, so all those neurons go to running the body, whereas in us, they go to doing cool things with our opposable thumbs, like writing code for porno sites. And, I don’t have a cite for this, but I recall reading somewhere that a female human’s body could deliver a chimpanze baby or a gorilla baby (don’t remember which) with no problem, and the reason childbirth is painful for her with a human is because a human baby is much larger, but since better than 50% of women survive childbirth, there’s no reason for them to evolve wider hips or a larger birth canal. (Of course, if they did, most of us guys would be in trouble since we wouldn’t “measure up” if you know what I mean…)
I heard a similar intersting tidbit about human babies having big heads and why they take so long to become independent compared to other animals. Seems that they are born after nine months or so because that is as big as they can get before it’s too dangerous for the mom to give birth due to a huge head on the munchkin. BUT, supposedly their brains aren’t finished growing/develloping yet; and they spend the next few months (or years) finishing their brains off outside the womb. I guess all the wires aren’t hooked up until a little while after the actual birth, so that’s why they are basically cute little vegetables (sorry) for so long and don’t walk/talk right away like an antelope. So if you think babies heads are big after nine months, just try giving birth to something with a head the size of a toddler!!
My info may be a bit sketchy here, but that’s what I’ve heard.
Oh yeah, brain size doesn’t have as much to do with intellegence as some may think. An octopus doesn’t even have a true brain, but they are known to be highly intellegent (for sea creatures).
What I find most interesting in regard to head size and intelligence, is the African Grey Parrot, a pinhead for sure. Communication skills that appear to be more than mimicry suggest a superior intelligence among the animal kingdom size notwithstanding. This site is one of several addressing this bird.
I agree with the others about brain size. There’s a general corrolation between brain mass & intelligence (see Carl Sagan’s “Dragons of Eden”), but the quality of the brain mass is a more important factor than the quantity.
IIRC, didn’t Neandertal (or another extinct member of the human family) have a larger brain than modern Homo sapiens?