Intelligence and Evolution

[Seeker]

If say, the eye has evolved independently about 40 times, why intelligence didn't? If it is desirable for survival/reproductive value, why haven't other animals evolved it independently of apes? As I said, the eye evolved in very different creatures several times. So likewise could 'intelligence'?

Does evolutionary theory have an answer for this? I hope I have framed the question correctly.

[rogue06]

If say, the eye has evolved independently about 40 times, why intelligence didn't? If it is desirable for survival/reproductive value, why haven't other animals evolved it independently of apes? As I said, the eye evolved in very different creatures several times. So likewise could 'intelligence'?

Does evolutionary theory have an answer for this? I hope I have framed the question correctly.

Other animals, including invertebrates like squid and octopi, have evolved intelligence. I think that your question ought to be why is it that only among apes has intelligence evolved as highly as it has. But then that's like asking why a certain type of animal is the fastest or whatever.

[rossum]

If say, the eye has evolved independently about 40 times, why intelligence didn't? If it is desirable for survival/reproductive value, why haven't other animals evolved it independently of apes? As I said, the eye evolved in very different creatures several times. So likewise could 'intelligence'?

Does evolutionary theory have an answer for this? I hope I have framed the question correctly.

As rogue06 said, cephalopods have also evolved intelligence, as have some birds.

Intelligence requires a larger brain. Energy spent building and running a brain takes away from the energy available for surviving and reproducing. A tapeworm does not need intelligence, so it has not evolved intelligence. Ants have evolved a form of collective intelligence, with the 'intelligence' (if it is that) being spread through the colony as a whole.

In short, intelligence will evolve where the benefits of intelligence outweigh the construction and maintenance costs of a larger brain.

[shunyadragon]

If say, the eye has evolved independently about 40 times, why intelligence didn't? If it is desirable for survival/reproductive value, why haven't other animals evolved it independently of apes? As I said, the eye evolved in very different creatures several times. So likewise could 'intelligence'?

Does evolutionary theory have an answer for this? I hope I have framed the question correctly.

Not a good question. The reality is yes intelligence did evolve independently in Cephalopoda as in squids and Octapi. Like eyes there is a strong survival advantage for intelligence. It is the ratio of brain size to body size and complexity of the brain that are advantages that lead to higher intelligence.

[Seeker]

I think it kind of boils down to how one defines the characteristic/trait of 'intelligence'.

But thanks for all the answers, regardless. :)

[shunyadragon]

I believe cephlapods and also birds by the way have shown intelligent problem solving abilities as defined as characteristic/traits of intelligence. Dogs do not, they show compathy toward humans when most other animals do not.

[Stoic]

If say, the eye has evolved independently about 40 times, why intelligence didn't? If it is desirable for survival/reproductive value, why haven't other animals evolved it independently of apes? As I said, the eye evolved in very different creatures several times. So likewise could 'intelligence'?

Does evolutionary theory have an answer for this? I hope I have framed the question correctly.

As others have pointed out, other species are intelligent too. Perhaps the question is, why didn't they continue getting more intelligent until they were as smart as us?

I suspect the answer is that greater intelligence (beyond a certain point) isn't usually all that useful evolutionarily, when compared to things like greater reproductive capacity, greater energy efficiency, greater ability to avoid predators or catch prey, etc.

It may be that it only becomes really powerful when it reaches a certain level, in a social species, with appendages suitable for creating and using tools.

[rogue06]

As others have pointed out, other species are intelligent too. Perhaps the question is, why didn't they continue getting more intelligent until they were as smart as us?

I suspect the answer is that greater intelligence (beyond a certain point) isn't usually all that useful evolutionarily, when compared to things like greater reproductive capacity, greater energy efficiency, greater ability to avoid predators or catch prey, etc.

It may be that it only becomes really powerful when it reaches a certain level, in a social species, with appendages suitable for creating and using tools.

Intelligence, as a general rule, does not seem to convey an evolutionary advantage that offsets the cost. Look at cockroaches. Not exactly noted for their intelligence but can survive in conditions that few other complex organisms can.

Moreover, there are some who argue that intelligence like ours was a side effect or unintended consequence of other factors.

Years ago I read a fascinating book where the author posited that human intelligence was a side effect of increases in hand and eye coordination that developed as our ancestors threw sticks and stones at prey. I don't think that is something most biologists follow but it serves to illustrate how intelligence might have developed as a side effect.

Another possibility is that cooking our food may have played a significant role in our evolving intelligence. Sure it made food easier to chew which allowed a reduction in our jaw size but some studies suggest that it is linked to a sharp increase in the size of our brain.

The point is that our intelligence may be more by accident than something that we were naturally evolving.

[shunyadragon]

Intelligence, as a general rule, does not seem to convey an evolutionary advantage that offsets the cost. Look at cockroaches. Not exactly noted for their intelligence but can survive in conditions that few other complex organisms can.

Moreover, there are some who argue that intelligence like ours was a side effect or unintended consequence of other factors.

Years ago I read a fascinating book where the author posited that human intelligence was a side effect of increases in hand and eye coordination that developed as our ancestors threw sticks and stones at prey. I don't think that is something most biologists follow but it serves to illustrate how intelligence might have developed as a side effect.

Another possibility is that cooking our food may have played a significant role in our evolving intelligence. Sure it made food easier to chew which allowed a reduction in our jaw size but some studies suggest that it is linked to a sharp increase in the size of our brain.

The point is that our intelligence may be more by accident than something that we were naturally evolving.

I disagree. The process of evolution is more opportunistic and adaptive to the environment. The independent evolution of intelligence in primates, sea mammals, paciderms, cephlapods, and birds is not accidental. The physical foundation of the brain and nervous system goes back to the earlies life forms, and the basics were there with the first seurocord ,brain, and eyes.

There is nothing accidental about the evolution of life by definition. Intelligence has adaptive advantage in evolution.

[Seeker]

Not a good question.

Well, sorry I didn't live up to your standards.