Why aren't all animals becoming smarter?

[Captain Kremmen]

Nature does not usually select for increase in intelligence greater than that needed for survival.

Ants are collectively quite intelligent
but they are probably not much smarter than they were
60 million years ago.

The difference in our brains from other apes is not great.
We have a greater density of neurons and a bigger, more convoluted brain.
How difficult would that be for nature to select for in other species if intelligence gave a general advantage?
Not difficult at all I think.


Why doesn't evolution generally select for intelligence?
And why have we been the exception?

 

[thatbiogeek]

It costs a lot too grow and "feed" a proportionally human sized brain. If the advantages of having such a brain and the intelligence that presumably accompanies it do not outweigh the cost, it would not confer a reproductive advantage to its bearer. It's always tempting to ask questions like this, why aren't animals smarter, why don't humans photosynthesize etc... But it isn't really a great line of thinking in evolutionary biology. Organisms exist in their present state because they have followed a precise line of evolution as a result of natural selection, genetic drift, etc... Wholesale prediction of what an organism will look like in the future or determining why an organism didn't evolve one way as opposed to another is difficult because we 1. don't know what kinds of mutations will be drawn to be selected for and 2. even if a mutation is present in a population, even if it has a selective advantage it may still be lost in the population. We can use population genetics to predict changes in allele frequencies through generations and possible scenarios if a mutation arises, however.

That said, I'm really not that familiar with brain evolution, at least not outside its basic development in animal embryos. I'm a plant girl myself

 

[Orleander]

Yeah, I am so sick of those damn squirrels that run out in the middle of the road and then hunker down waiting for you.
Do they do that with every predator? After years and years, have they not learned what a car is?!

 

[thatbiogeek]

No, they're just being devious like on that commercial...

 

[iceaura]

Yeah, I am so sick of those damn squirrels that run out in the middle of the road and then hunker down waiting for you.
Do they do that with every predator? After years and years, have they not learned what a car is?!

City squirrels, in my experience, are much more likely to run straight across the road. Country squirrels are more likely to double back under your wheels. Neither one has time to think about it - intelligence that required thought would kill either one.

So there's evolution visible, apparently from Darwinian selection, but not of intelligence.

 

[orcot]

Nature does not usually select for increase in intelligence greater than that needed for survival.

I Think it takes a rather specialist pelvis to pop a baby head out of, I'm not that educated in this region but I also believe that human birth is rather dangerous to the mother and that advanced pregnant women have a below average mobility range then most animals, also human children are in practical terms extremly stupid for a enormous amount of time (5 years or so) unable to defend themself or run away, hide, find food a even bare the climate.

 

[spidergoat]

Animals are very intelligent. I know my cat is pretty smart. Squirrels evolved in forests, where crossing a clearing was dangerous, and consequently accomplished as quickly as possible. That's why they run across roads instead of being more careful.

I saw a program about African wildcats, and they are brilliant at hunting; not only stealth, but strategy.

 

[mikenostic]

It costs a lot too grow and "feed" a proportionally human sized brain. If the advantages of having such a brain and the intelligence that presumably accompanies it do not outweigh the cost, it would not confer a reproductive advantage to its bearer. It's always tempting to ask questions like this, why aren't animals smarter, why don't humans photosynthesize etc... But it isn't really a great line of thinking in evolutionary biology. Organisms exist in their present state because they have followed a precise line of evolution as a result of natural selection,[/quore]
Where is natural selection for us humans? It seems that we have more or less outsmarted natural selection. We don't kill off our weak or sick specimens. We allow them to live their lives too.

That said, I'm really not that familiar with brain evolution, at least not outside its basic development in animal embryos. I'm a plant girl myself

Is that a picture of you in your avatar? You're cute! :roflmao:

 

[Orleander]

...Squirrels evolved in forests, where crossing a clearing was dangerous, and consequently accomplished as quickly as possible. That's why they run across roads instead of being more careful. ...

so why aren't they still evolving to learn not to run into the road??

 

[spidergoat]

They can't avoid crossing roads. Roads are everywhere.

 

[mikenostic]

They can't avoid crossing roads. Roads are everywhere.

But why do they seemingly wait until a car is 20 yards/meters from them before they decide to dash out in front of it?
I'm sure that acorn or walnut laying on the other side of the road isn't going to magically sprout legs and run away in the time it would take for the squirrel to yield to crossing cars, before he can cross and go get it.

 

[spidergoat]

For them a car is like a hawk. If it keeps going towards you, you don't stand still, you run!

If squirrels stopped this behavior, they would get picked off by predators.

 

[Oli]

After years and years, have they not learned what a car is?!

Of course they have: but it's well known that the favourite hobby of squirrels is collecting car licence numbers - some just can't write them down fast enough.

 

[mikenostic]

For them a car is like a hawk. If it keeps going towards you, you don't stand still, you run!

If squirrels stopped this behavior, they would get picked off by predators.

That's a good point. I never thought of it like that.

 

[spuriousmonkey]

A brain is an energy guzzler.

 

[Orleander]

And what about deer? They are no better than squirrels. Cows are smarter than that..and cows are dumb.

 

[fo3]

...Squirrels evolved in forests, where crossing a clearing was dangerous, and consequently accomplished as quickly as possible. That's why they run across roads instead of being more careful. ...

so why aren't they still evolving to learn not to run into the road??

There have been enough cars around to cause considerable death among squirrels or any other animals for less than a century. Although it seems to be presenting a huge evolutionary pressure in favor of squirrels that avoid roads more or wait for an opportunity to cross the road while there are no cars approaching, evolutions simply does not move that fast. There are by far not enough mutations occurring naturally to cause so large behavioral changes over such a short amount of time. That itself would be a huge disadvantage, because a species that would go through so large changes over every potentially temporary change in the environment would be selected against in competition with other species. All that aside, I can imagine that there are a lot larger problems presented to squirrels and other animals with the increase in human population than the possibility of being hit by a car, as adapting to the changing food sources and nesting locations. With all the changes in their natural habitat, getting hit by a car might be a lot smaller problem than you might imagine, and the natural selection is most likely "concentrating" on different problems at the moment.

 

[thatbiogeek]

It costs a lot too grow and "feed" a proportionally human sized brain. If the advantages of having such a brain and the intelligence that presumably accompanies it do not outweigh the cost, it would not confer a reproductive advantage to its bearer. It's always tempting to ask questions like this, why aren't animals smarter, why don't humans photosynthesize etc... But it isn't really a great line of thinking in evolutionary biology. Organisms exist in their present state because they have followed a precise line of evolution as a result of natural selection,[/quore]
Where is natural selection for us humans? It seems that we have more or less outsmarted natural selection. We don't kill off our weak or sick specimens. We allow them to live their lives too.

I don't think we're under much selective pressure now, except with regards to infectious disease and general deleterious mutations, however in our evolutionary past we were subject to selection. We exist as we are now because of a precise line of evolutionary changes as a result of natural selection (and I should have put other evolutionary forces as well :shrug

I think you'll agree we were subject to selective pressures in our past- predators and what not

Is that a picture of you in your avatar? You're cute!

That's the south park me but the background image is my real lab (was my real lab anyway) I had way to much fun playing with that south park generator link that was posted in the "about members" section of this forum (I think that's where it was posted)

 

[joepistole]

Intelligence pays off to but its value is limited by the creatures abiltiy to use it. Factors of limitation are: dexterity (ability to manipulate environment, socialability). Without the abiltiy to manipulate the environment (hands) growing brain size is not efficient. Sociability increases intelligene with the sharing of ideas...without sociabibility ideas are lost and must be recreated anew each generation. It just so happens man has both the abiltiy to manipulate his environment and is a social animal. It takes a while to achieve critical mass, and I think we achieved critical mass last century.

 

[spidergoat]

Think about the level of intelligence that would be required of a squirrel to learn how to predict the behavior of an automobile! Most dogs can't even do this unless specifically trained.