Big head = big brain. True or false?

Question

What about big belly?

Answer 1

It's both true and false.

Some creatures have to have larger heads to accomodate more brains (compare a human skill to an ape skull and you'll see what I mean). On the other hand, there are plenty of critters who have other stuff in their heads instead... like huge jaws.

If you really want to compare brain sizes, what some people use is called the EQ, or encephalization quotient. Most larger creatures need to have larger brains simply to run their larger bodies. So one way to tell if there's any 'extra' there is to compare the weight of their brain to the weight of their bodies. That's the EQ.

Looking at EQ, you find that dolphins have the highest EQ of all ceteceans, sharks have the highest for any fish, octopuses have the highest of any invertebrate, and humans beat the pants off them all. All of which is more or less what we would expect for a a broad enough estimate of intelligence to be applicable to all these creatures.

The problem with brains is that they require lots of energy to work properly. So in theory few creatures will develop more brains than they need to survive well. Even really big ones. One of the more interesting correleations among EQs is that predators almost universally score among the highest... they not only NEED to think more to outwit their prey, but they have more energy available to them to power those brains.

Which answers your second question as well: a big brain does need a big belly to run it! ( :

Answer 2

In general, the size of the head doesn't necessarily have a strong corellation with the size of the brain inside it.

Great white sharks, saltwater crocodiles, and Tyrannosaurus rex all have HUGE heads, but their brains are all remarkably tiny.

However, those of us with big bellies are definitely smarter than skinny people. Don't know why, we just are. There's no use arguing about it, you'll just overtax your skinny little brains, and have to go have a saltine or something.

Eat a sammich for science!!