What is the most widely accepted theory for why human beings developed their supposed superior intellect, whereas the billions of other creatures on this planet did not?
There are some obvious costs to this process. The larger brain means that they have larger heads at birth, making their delivery much more dangerous. They must also be born more prematurely than other animals, before their heads become too large. Also, large brains expend large quantities of energy, even when they are not being used. Why did these large brains evolve? And why only in humans??
My quick guess is that the competitive benefits to being smarter outweighed the disadvantages you stated. Smart proto-humans survived more than dumb proto-humans. Also, smart male proto-humans may have been more successful at getting the proto-ladies than dumber proto-males.
One theory why it occurred only in humans is because of those opposable thumbs. Being able to manipulate objects as well as we can made intelligence have a huge payoff.
Given the relative slowness and weakness of the species, I would imagine predatory pressure had something to do with it as well. Can’t outrun or outfight a leopard? Better be able to outsmart it.
We had thumbs and we could talk, or at least form lots of consonants and vowels.
The key with the thumbs it that, being opposable, they allowed us to grasp objects and manipulate them much more easily and any ape before us. With this ability came the selective pressure towards proto-humans who could make better use of this gift. Because of our thumbs’ existance, the brain slowly evolved to be able to take more advantage of them.
With speach, or at least the capacity for it, we began to rely on communication to survive, and the better you understood verbal communication and could speak it, the better chance that you had.
Basicly ‘I think therefore I am’ is made possible by a rearrangement of finger bones and an upright stance (which shaped the throat such that we could make all manner of sounds).
Are you sure there is any intelligence in the world?
At any rate, I think it is safe to say that there are as many theories on the subject as theorists. So for what it’s worth, my theory is that at some point, the guy with the biggest mouth, rather than the one with the biggest muscles, became king of the hill and it all went downhill from there.
Human intelligence, most likely, evolved as a result of intraspecies competition among humans, not simply as a survival mechanism to deal with the external environment. After all, millions of other species deal with the physical environment and with predators and competitors perfectly well without the need for intelligence.
Humans are social animals, and those individuals intelligent enough to manipulate ocial situations to their own benefit had a high selective advantage within the group. And those groups that had high social cohesion had an advantage in competion with other human groups.
On major cognitive ability of humans is the ability for empathy, that is, the ability to identify the motivations of other individuals even when they seek to conceal them. This requires a great deal of intelligence, as does the ability to conceal one’s own real motivations for others.
I think that the unique hypertrophy of human cognitive abilities was driven by this kind of competion within and between human groups, a kind of evolutionary “arms-race” in a way similar to those that lead to the evolution of the giant antlers of the Irish Elk or the tail of the Peacock.
I agree with Colibri that these probably were not the sort of egghead skills that people think of, pure logical analysis which we are really quite bad at in reality. Rather cognitive skills that allowed better, more efficient group function, as well as moderately higher individual survival.
I don’t know that intra-Homo competition would be the driver for that. It probably was among them, though. Above all as we get around to the Erectus to early Sapiens stage.
And as cited in some recent threads on race etc., some recent but perhaps shakey research suggests a single mutation, in Africa, leading to full speech ability. Spread rapidly.
As to “why” and “why not” – the only answer science can give is, well a nice combination of chance mutations got us to this point, in combination with appropriate selection pressure. Why no other species to date, well that’s an impossible question to answer other than the combination of the right chain of mutations to get there and the right selective pressures to ensure the benefit of those mutations outweighed the cost just did not occur. To date.
Further speculation goes beyond GQ and into GD or IMHO territory.
(In answering of course I have adopted the implicit definition of intelligence as one focused on tool-using, socially complex society-building intelligence resembling our own mode, that would create a object based society.)
If a mutation caused an ability to communicate better and this caused a push for a larger brain and intelligence, then if we could genetically introduce the same type of mutation into an animal, such as dogs, and turn them loose for a million years, would they develop intelligence?
Probably not. There’s a constant evolutionary interplay among body design, environment, and brain capacity that makes it hard to consider factors in isolation.
An outsider looking at Earth ten million years ago would have noted a wide range of intelligence among warm-blooded animals, and probably would have had no trouble placing rodents at one end of the spectrum and apes at the other. At that time, however, it would not have been obvious that intelligence conferred clear advantages; it was more of a “niche strategy” for a few species of primates, with relatively low populations, in selected environments.
Some time over the last ten million years, obviously, something changed. As previous posts suggest, it may have been that the evolution of upright posture combined with intelligence to redouble its survival advantages. Or it may have been the pure happenstance that our ancestors evolved a “critical mass” of intelligence that finally outweighed its disadvantages, such as prolonged infant dependency. By Neanderthal times humans were much more numerous and widespread than any previous species of ape.
The final piece of the puzzle, of course, was the development of speech. This didn’t necessarily make humans any more intelligent, it simply allowed us to pool our intelligence and achieve more than we could have in isolation.
When looking at intelligence as a survival trait, it’s best to see it as the trait of “on the fly” adaptability. When the change in ecology (like the one from jungle to savannah) occurs faster than hardwired adaptations can keep up with, it’s more important to be able to rewrite the software.
I would also argue that intelligence was selected for on a intra and interspecies level as well as an intra-tribal level. More intelligent people can make better weapon to fight lions, better weapons to fight enemy tribes, and better decisions to negotiate a more powerful position within the tribe to get the heartiest females.