Why is the brain bigger than a walnut?

[Phrak]

Why is the brain bigger than a walnut?

 

[Evo]

Why would it be the size of a walnut?

 

[Phrak]

Guess i'll have to go with my six year old's answer,

"So we can know more stuff.".

Dad, "Why should we know more stuff?"

"So we can do our jobs."

Dad

"Like a police. Like a fire fighter!"

Daddies are so dense.

 

[Math Is Hard]

Some brains are the size of a walnut. I think cat brains are about that size.

Brains are limited by skull size. From what I understand, mammal brains got around that limitation by becoming crumpled. The surface area to volume ratio is increased allowing for more cortex and higher level processing.

I'm not sure why we never evolved larger skulls for our expanding brains. It probably had something to do with limitations on the size of the pelvis and birth canal.

 

[Cincinnatus]

It's also not clear that having a larger brain has anything to do with being smarter. Lots of primates have brains just as large if not larger than we do but no one seriously argues that they are more intelligent.

 

[Moonbear]

I can think of a lot of species with brains smaller than a walnut. Mouse, rat, rabbit, bat, guinea pig, vole, squirrel, zebrafish, chicken, pigeon, salamander, frog, etc.

Is there a more specific question that prompted the original post?

 

[Phrak]

So... A walnut is good for breeding, eating, running way, chasing things, nibbling on greens in a dark hole. What's the the rest of the cheese cake good for?

It costs about 100 Watts just to keep it booted, doesn't it? So maybe it's less, but it's still must cost something to keep it plugged in.

 

[Mental Gridlock]

I'm not sure why we never evolved larger skulls for our expanding brains. It probably had something to do with limitations on the size of the pelvis and birth canal.

It's possible to accommodate more brains by changing skull shapes. But skull size and brain size has been increasing all along and we have larger of each than say habilis or erectus.. It would probably continue to do so and whatever sapiens evolve into I imagine will have even larger brains than we did. I assume the birth canal can evolve to adjust as well, but even if it can't be done the shape can change, it doesn't have to be wider it can be longer and still fit through the birth canal. Earlier ancestors had more in the front of their skull, they could probably take a bigger bite, but their cranial region couldn't hold much. That evolved into what we have where the front is rather pushed back and a much bigger cranium resulted. I imagine the evolution will continue in this direction. Maybe we'll wind up like the coneheads.

 

[Evo]

It's not so much the size of the brain as it is the cortical folds. I've posted this in the past, but it bears repeating.

http://serendip.brynmawr.edu/bb/kinser/Int3.html