I am with Rahven in this one, I think intra-specific competition (i.e. both sexual and social selection) is what ultimately drove us to have the brain we have today. This is true for almost all "extravagant" organs in nature, do silverback gorillas "need" all that muscle? Do caribous need those huge antlers? Do birds of paradise need such extravagant feathers? All of those are are under selection by competition either between males or between individuals.
One thing to remember is that what we see today are only the nearest relatives left, those that did not pose a serious threat to modern humans.
That's completely true and often missed, when you say "our brain is much more powerful than our close relatives", you have to remember that there are many other lineages of humans that went extinct (think Neanderthal), not to mention the "close" relationship between us and apes dates at least 3 million years.
You guys are confusing things again. You have to remember that natural selection (and therefore brain evolution) stopped in humans thousands of years ago, but the brain that we have today is the same that Homo sapiens had hundreds of thousands of years ago, note the different time scales. So brain power came way before technology (which seems to be at least part of your measure of intelligence).
Now, the appearance that we are light years ahead of every animal out there in terms of intelligence is completely due to technology and cultural evolution (and not brain power). So, if you compare a hominid hundreds of thousands of years ago (but with the exact same brain that we have today) to a Gorila or Chimp you won't find that much difference in "intelligence".
What sets us apart is that we learned to store and share information like no other species. It is a simple behavioral character that revolutionized the course of our species evolution.
Now here is some food for thought, we understand very little about our brain. Some people with mental "disorders" like autism sometimes demonstrate extraordinary math skills to a point where they resolved extremely advanced math tasks without ever being taught how to.
Just thousands, to be precise the last two thousand.
The population increase that humans went through in the last 2-3 thousand years has few parallels in nature, and there is plenty of evidence showing that selection does not operate in expanding populations, I can dig up refs if you want. But to put it simply, natural selection operates under the premise that some of your progeny will die (and with it presumably your "weak" genes), so in order for natural selection to operate, a certain percentage of the population has to perish. But in today's society this is not happening anymore, or in other words, both the fittest and the weakest are surviving. If both are surviving there is no selection.
Don't take me wrong, this is not a bad thing, as it allow us (as a species) to have anomalies like Einstein or Hawking, but I assure you a person with a much lower IQ left many more descendants than those two individuals somewhere else in the planet.
You are absolutely correct here, and we agree, I am measuring "evolution" here in the present. We know it is acting in many species as we speak, and it is not on humans now (because we are all reproducing before we die). It might very well start again in the very near future, but for now it seems not to be acting, and that is my point... Our raw "brain power" is not different from that of a cave man
I'm sorry I have yet to learn how to properly quote and respond messages. I meant to direct my post to Tangle
This seems to be as flawed as the 'technology' argument. In fact, the way we store and share information is mainly by using technology. But for most of mankind's existence we have taught our young in exactly the same way that other animals do. We may currently have very clever ways to store information, but those methods are very recent compared to the existence of humans.
So, we agree here, and this is exactly what I meant by "cultural evolution", it's a snowball effect, the better we get at transferring and storing information, the better our technology gets (and vice-versa).
Going back to Tangle's point, an interesting question would be if those aliens that he mentions arrived here not today, but 50 thousand years ago. We, as species, would have virtually the same brain (50k year old skulls are anatomically identical to ours), but would the aliens consider us any more intelligent than Gorillas and Chimps?