What bothers me about the evolution of Man

This was a puzzling question to me as well when I first learned about evolution. I recall an old High School biology teacher telling the class that humans evolved bigger brains "to use our hands," which is patently ridiculous - spiders have miniscule brains but are somehow able to control eight seven-jointed limbs plus pedipalps and spinnerets.The real answer is that evolution doesn;t have a goal, and while it's tempting, you can;t look for a goal like "to use tools better." You need to look for a relative selection advantage, something that makes a more intelligent person more likely to survive and mate and have more offspring that relatively less intelligent competitors.We don't need huge brains to fill an environmental niche. You're right - we're astoundingly smarter than any other animal on Earth. Something like 20% of our metabolic energy goes to our brains alone! So how did we get so smart? Typically we'd be talking about slightly more intelligent individuals better surviving some selective pressure, but that just results in a plateau as the immediate selective pressure is overcome.But there's one possibility that involves an intellectual arms race without limit.Competition with each other.The smarter we get, the smarter the competition, and so even smarter individuals still have a selection advantage. It's an evolutionary spiral. Each increment is small, but the selective pressure is never actually overcome because there are always more humans to compete with.There's a book called Chimpanzee Politics by Desmond Morris that contains an interesting story observed in a group of chimps.One chimp was attempting to challenge the current dominant of the group. A third chimp gave him assistance - not directly, but by interfering with the current dominant's "allies" in the group and distracting them. The challenger won and became the new dominant. The third chimp then double-crossed the new dominant by joining up with the recently-defeated dominant...and the third chimp became the new dominant of the group. Chimps engage in that level of political intrigue. Humans take social maneuvering to an entirely different level.It really is an arms race without limit. From our ape cousins to modern man, higher intelligence relative to the rest of the group has retained a selection advantage. It's not the only pressure, certainly - evolution isn't a single-issue voter. But humans play complex games of intrigue, deception, and struggles for dominance competing with each other than have thus far outstripped the intellectual challenge of any environmental selective pressure.

You vastly underestimate the difference in intelligence shown between humans and other species.Some birds have been shown to be sufficiently intelligent to recognize the patterns in stop lights and drop nuts in front of cars that are stopped so that they'll crack the shells when the lights turn green.Humans have been shown to sufficiently understand the basic workings of the Universe to transmit information on a global scale nearly instantly, calculate the motion of planetary bodies, and escape the gravity well of the planet.Various species of ape participate in complex social hierarchies.Humans do that, too - with social groups many orders of magnitude larger.Many animals make "nests" of one sort or another for shelter.Humans build skyscrapers. We're thinking about orbital habitats and permanent bases on the moon, and we have the intelligence to actually pull it off.The level of disparity in adaptive intelligence is so large that there lacks a sufficient scale. Our brains are like supercomputers while the most intelligent animals are basic calculators. Our closest competition isn't close at all.And yet human intelligence requires major sacrifices. We spend far more energy on our brains than other animals, around 20% of our total metabolism goes to fuel our brains instead of our muscles. We would starve to death more rapidly than a similar organism that only devoted 5-10% of its metabolic energy to its brain, and that's a major disadvantage. Others have pointed out the sacrifices made in reproduction, that human babies are born significantly early because the cranium is so large that it has to finish development outside the womb. This is another huge disadvantage.The only reasonable solution that accoutns for how we could establish such intellectual disparity in the face of such significant evolutionary disadvantages is a self-perpetuating cycle where greater intelligence compared to the group provides a continual reproductive and survival advantage one generation after another. The best example of this is social competition, where the individuals of our species compete with each other for social dominance, where such dominance leads to both advantages in survival and in reproduction. The offspring then compete with each other, and so on, in a cycle that never ends.

1) I realize that others are including extinct species, specifically extinct hominids that are closer relatives to humans than extant apes, but I'm not. It's rather tough to gauge the relative intelligence of an extinct species, especially since we'd also be talking about our own extinct ancestors rather than modern man in the comparison. I'm only comparing modern Homo Sapiens Sapiens to other extant species.2) Our ability to share information with other members of our social groups on an abstract, as opposed to demonstrative level is part of what sets us apart intellectually. Human beings don't have to learn everything solo, or even mimic what we see other individuals doing - we can communicate abstract concepts through language rather than demonstration. Other species can't do that. They learn alone, and some of them are capable of mimicking behavior they see in others, but you can't give a team of macaws all the tools and material and blueprints necessary for building a skyscraper and expect them to understand the plans.

Reread my posts. I never claimed or agreed that human-level intelligence "only evolved once." I've only pointed out that human-level intelligence is vastly out of proportion with extant species, and specifically is absurd overkill for "normal" environmental challenges in terms of selection pressure, particularly with the downsides of growing and fueling a human brain. I've been talking about the specific, likely selective pressure that would cause human-level intelligence to evolve. You're confusing my arguments for other people's statements. Not really. It's the ability to acquire and process knowledge that provide advantages, not knowledge itself. 3-year-old human brains aren't fully grown yet. The human brain finishes it's primary development around 20 years after birth.Comparing immature humans to animal intelligence is patently absurd. One could argue that a 1-week-old horse is smarter than a 1-week-old human child because the human child doesn't even have full control of its limbs yet, while the horse will be walking. Insects are mobile from birth, while newborn humans can't even crawl.An adult human is incredibly more intelligent than an adult chimp. It's not even a close comparison, despite them being some of our closest extant relatives.