Sunstone said:
Why do so few species have high intelligence? If high intelligence is a successful survival strategy, why hasn't it evolved more often?
Simple. High intelligence isn't actually a successful survival strategy. The brain is a
very energy-intensive organ, and until you reach a critival level of intelligence, spending extra energy on it is a waste of resources. Think of a small brain as a Corolla, and a large brain as your F1 racing car. Sure the F1 racing car goes faster, but it also uses a lot more fuel. Evolution doesn't actually favour high intelligence: it favours survival, and you actually need pretty special circumstances for high intelligence to become boon. Otherwise you're just bleeding fuel when you could be using less than 10 litres per 100km.
Homo Sapiens is successful at the moment, but we haven't always been. At one point, our numbers dropped below 2000, and
You'll find that most of the more intelligent animals are meat-eaters, and there are two main reasons for this: firstly, meat is a more efficient energy source than plants, so meat eaters can spend less energy searching for food, which means they have more energy to spare for their brains; secondly, many meat-eaters are pack hunters, which requires a degree of cooperation that necessitates a higher intelligent. Herds of herbivores, while they may be social, do not require much in the way of cooperation. The benefits that they derive from being together are related more to making the individual herbivore a harder target than they would be if they were alone, and the strategies which they use (mainly stampeding and cooperating to drive off their foes) require far less coordination than the tactics used by carnivores. I know there are exceptions (such as elephants), but they are in the minority.
Also, if you look at the native animals of Australia (which has a very harsh climate), you'll actually notice that marsupials tend to be the dunces of the animal kingdom. If you live on a contintent where food is scarce, then you're unlikely to survive if you waste your energy on being smart. Koalas even have brains that are too small for their heads, and have the ability to nearly turn their brain off, save for basic functions, because they have become so energy-efficient.
There's also the fact that the advent of sapient life (ie. humans) also has a tendency to preclude other forms of sapient life. Of all the species of the genus
homo, only
homo sapiens is still around today. Now, I know that there are various other reasons for the decline of the other species of human, such as the ice age and the neanderthals overspecialisation, however our ancestors intelligence gave them an edge when competing with the other species of
homo. Now, I know that I've just been saying that intelligence isn't actually a good survival trait, however once you reach a certain critical level of intelligence, it actually becomes useful.
Especially if you have opposable thumbs with which to make tools. Without opposable thumbs, human-like intelligence is a bit useless, really. Can you imagine a pair of sabre-toothed tigers with human-like intellgence? I can think the conversation would go something like this:
Yugi: "So, what are you doing today, Kaiba?"
Kaiba: "Oh, nothing much, Kaiba. I had this fantastic idea, though, because I'm a child genius, and I would be a billionaire, but I still haven't figured out a way to pick up my wallet without biting holes in it."
Yugi: "Yeah, what's your idea?"
Kaiba: "Well, rather than leaping on things, which takes heaps of effort, we could get some pointy sticks and throw them at our prey. That way we'll use less effort, and won't have to worry about being injured as much as usual! I'm a freaking genius!"
Yugi: "That's really super special awesome, Kaiba! How do you propose we throw these pointed sticks without hands?"
Kaiba: "..."
Anyway, I digress. Amongst many animals, humans are actually detrimental to the species chances to become more intelligent. Sheep and cattle, for example, are bred for docility, amongst other things, which generally means to an extent we've been selectively breeding them to be docile. Some animals, such as dogs, we've probably been breeding to become more intelligent, so as to increase their usefulness to us, but at the moment, there's a limit on how intelligent we'd want them to be. Of course, there are other animals which are much closer to attaining human-like intelligence, such as the great apes and dolphins, however humanity's success has been rapidly destroying their habitats, thus limiting their chances to attain sapience. High intellince really seems to be an all or nothing proposition: either you die out, because you're devoting too much energy to your brain, or you become immensely successful due to your large brain allowing you to come up with things like agriculture, iron smelting and antibiotics.
... I hope that answers your question in some ways, because if it doesn't, then it's a bit of a waste of bandwith, really.
