answersLogoWhite

0

Big brains seem to be pretty rare in the evolution of animals on this planet. One of the reasons for this is cost. Keeping our brain running is expensive. Just consider these facts.

750-1000ml of blood flow through the brain every minute. (3 soft drink cans worth)

In that minute the brain will consume 46cm3 (1/5 cups) of oxygen from that blood.

Your brain is about 2% of your total body weight but uses 20% of your body's energy.

The energy used by the brain is enough to light a 25 watt bulb.

In evolutionary terms this would make a big brain pretty rare. Think of any struggle between predator and prey. Say a lion and a gazelle for example. There's camouflage in their colouring so they are harder to see in long grass and there's speed and agility. The gazelle's ability to jump high. Now in this struggle the cost of either lion or gazelle to evolve a big brain is too big compared to what they'll lose in speed or agility before that brain would develop enough to make a real difference. This is true of most predator/prey relationships.

the other problem of developing a big brain is what do you use it for. You need a good way of manipulating the world for a brain to make use of it's abilities. Look at your hands, look at your thumbs. Brilliant for manipulating anything you come across. Perfect for grasping a stone or a stick to throw at or hit any approaching predator. Something to make up for what you lose running that expensive lump of grey matter.

Lots of the larger brained animals also tend to be social. Managing complex social relationships in a pack, group or family tends to increase the selective pressure on a larger brain.

So it has to be a situation in which there's a good selective pressure for a brain to grow to a large size in a body that has a good starting shape to take advantage of it.

Dolphins are pretty smart (and self aware) and so are parrots. They don't have a good body structure to really take advantage of it. A parrot can use it's beak and legs to manipulate simple odjects in a basic way, but it's nowhere near what a primate has.

Now for a creature that has a pretty big brain and decent limbs for manipulating objects other than primates look at the octopus. That is one smart animal. If humans were to become extint, that's the animal other than chimps and gorillas that might be a candidate for becoming super smart given the right selective pressures

There are other costs to a big brain. One is probably Schizophrenia (see link in the source section). It's also likely that our brain is as big as its going to get. Any further increase in size may well be disadvantagious due to the problems our brain has been left with growing to this size in the first place.

User Avatar

Wiki User

13y ago

What else can I help you with?

Related Questions

What is a sentence for anthropocentric?

Many humans are anthropocentric; they think humans are the only beings that matter.


Are humans gods or are they simply mortal beings?

Humans are mortal beings, not gods.


How many beings are there in space except humans?

Total of two but only one that is not human.


Have animals ever been on the moon?

No, animals have never been on the moon. The only living beings to have visited the moon are humans during the Apollo missions.


How would you use arrogant in a complete sentence?

To believe that humans are the only intelligent beings in this world would be arrogant.


Are there a such thing as living ghosts and dead ghosts?

yes there are ghost or rather beings visible only to certain humans.


Did humans live at the time of the dinosaurs?

No, humans beings are more recent.


Can methane gas be food?

Not for humans beings.


Are humans beings animals?

Yes,they begin in animals and then slowly involve into humans.


What scientific nomenclature separates humans from the animals?

Strictly speaking, only human beings use scientific nomenclature, so I would have to say that all of it separates humans from other animals.


Will humans and robots ever be able to peacefully co-exist?

They already do. As robots are not sentient beings, the possibility for a human-robot conflict does not exist as the conflict would be one-sided. Robots are the creations of humans and can only do what they are programmed to, even those with "artificial intelligence". Because of this, robots are not even living beings and therefore do not have an existence of which to coexist with other beings.


Are people human beings?

People are humans and humans are comprised of people,,,so the answer is yes.