I've been struggling with this question for some time now. A member of my family and I recently got into a debate about what is natural and what is unnatural. They are Christian so their opinion was "naturally" a warped one, but it got me thinking nonetheless.
I think that what separates us from other animals is fairly straightforward from a cognitive and technological perspective, but no one, not even the omniscient Google, has been able to give me an answer as to WHY this is the case.
Why are humans more technologically and cognitively advanced than other animals? Why are we the dominant species on this planet? Are we more evolved than other animals? If so, why have we seemed to evolve further (and faster?) than others?
On a less scientific note, do you envision a world where humans de-evolve or stagnate in their evolution allowing a new dominant species to take over?
And yet, we are everywhere, the most widely-distributed mammal on the planet.
It's not proper to say that a species can "de-evolve". Every species around today is the best at surviving in the niche that it survives in. We could not have survived in the niche where our Neanderthal ancestors were rocking out. They could not survive in the niche that we live in today. Natural selection does not select for what is better over all time, it just selects for what is better at the moment.
I see no reason why another species could not arise as "dominant" (fuzzy on what this means?). I think it's pretty feasible for our species to suicide out with religious fights, especially with the increasing power in weapons. (totally made up that term!)
regarding cognition, there are a billion theories. Read Ellen Dissanayake. She rules.
One (poorly communicated here) idea says that if you're too weak to fight a bear directly, it helps to be able to plan a trap ahead of time, which requires thinking.
With regards to the "de-evolve" comment, what I meant was "to re-evolve previously lost traits," something along the lines of frogs which have re-evolved lost lower-teeth.
A lot of people have pointed out the problem with the semantics of my question, and I wholeheartedly agree with all of the points raised. I slapped the post together haphazardly because I'm at work and don't have internet access at home at the moment, but if it's any consolation I cringed as I typed words like "dominant," "re-evolved," and "advanced."
HowÂ is probably a more useful word thanÂ why, but most people still understand the question. Â It's also unscientific to infer value judgments wrt what's supposedlyÂ betterÂ orÂ more advanced, orÂ more evolved, etc, which I've seen in a lot of responses. Technologically and culturally we beat other species to the punch, for several reasons. (I'm not sayingÂ the punchÂ isÂ good. I'm just saying our species beat all other species to it.)
In any case, in answer to your question, I think there is too much to explain simply. You'll see a lot of people giving a lot of reasons, or you'll see them arguing over which is most important or which adaptations or behaviors came first. So I think that getting an overview first might be more helpful than parsing through "expert" opinion about the perfection/imperfection of our knowledge about human history. Ha, there is more than one way to get an overview, too.
So this overview is just one suggestion, from me.
Here is an interactive, graphical timeline.
Also, in spite of some people's "we humans (or at least those Deists) are lower than pond scum" cynicism, perhaps we can aim more for I'm OK, You're OK and consider more positive approaches? Here is an interesting view of civilization's history, and possible future. (Direct link here, in case of problem with following embed code.) The whole 11 minute video is very good, but perhaps from about the 5-1/2 to about the 8 minute mark is the most pertinent.
One thing that should be made clear is that we are not 'more evolved' than any other living species. We are exactly as evolved as every other type of organism, since we have been around exactly as long as them, which follows from the fact that we share a common ancestor, the first replicator. Consequently, there is no such thing as 'de-evolution', only evolution divergent from our parochial notion of what constitutes advanced life. If we develop into husks of bodies with gigantic brains, diverting resources from our superfluous physical bodies in order to feed our more powerful brains, then we won't have 'de-evolved', though it would seem so to our recent ancestors who had to hunt for survival. We would rather have evolved to better suit our new environment, which presumbaly would include a lot of technology to do the heavy lifting for us.
However, it is more or less accurate to say, as you do, that we are 'more cognitively advanced' than other animals. You must understand, however, that evolution is not a process driven by an end goal. It is easy for us to imagine that the 'goal' of evolution is to produce intellegent life capable of radio communication, space-travel, mental existance unburdened by a body etc. However, evolution must always be seen as a blind, undirected process which operates on the logic that replicators which are well-suited to reproducing in their environment will come to dominate that environment. One could better say that the life forms that we think of as 'primitive', such as the prokaryotes, are actually more evolutionarily advanced, since they found such an effective form of replication so early in their evolutionary history that they have changed very little while we have changed dramatically over the same period of time.
An element of game theory is at play here, which will be familiar to anyone who knows the prisoners' dilema. Consider the trees in a rainforest; it is advantagous to an individual tree to be slightly taller than its neighbours in order to collect the most sunshine and rainwater. Thus, trees in a rainforrest engage in an arms race that ends in all the trees in the forest using the maximum amount of their resources physically possible to add to their height. A more advantageous arrangement would be for all trees to be uniformly short so that fewer resources are wasted on competition and more on whatever it is trees would like to spend their resources on (I honestly am not sure what this would be). In the case of human evolution, the physical imperfection of our distant ancestors led to competitive adaptations such as the ability to move, mechanisms of self-defense and predation, cognitive function and, eventually, the ability to conceptualize contingencies rather than just comprehending reality. Our dense, advanced brains are the result of an evolutionary history in which the ability to out-think your competition meant the difference between life and death, or between mating and not mating. Thus, our bodies eventually approximated the ideal ratio between a big, smart brain and a body capable of responding to that brain's directions. In terms of sheer replication, though, it would have been more efficient if everyone had 'agreed' to maintain a certain level of sameness, a maximum variation from the mean, so that everyone could put all of their energy into reproducing instead of having to worry about competing with each other. Of course, this would mean that there'd only be single-celled organisms, or something even more primitive, but we can immagine what it'd be like if it happened to our barely pre-human ancestors (in fact, the Neandrathals are probably just our evolutionary brothers who didn't 'deviate from the mean' enough, and were thus overtaken by a more sucessful population descended from those who did). Our evolution may have progressed in any number of directions (better night vision, stronger running muscles, more weapon-like nails) without necessarily giving us a bigger brain, but we became locked into an evolutionary arms race when intelligence became a powerful enough survival/reproductive tool for natural selection to make use of.
As should be clear by now, those who suggest that eating cooked food led to bigger brains have cause and effect reversed, although the change in diet undoubtedly facilitated a further 'growth' of the collective human brain that would not otherwise have been possible. Cooking, agriculture and even 'animal' behaviour like pack-hunting cannot occur, however, without a certain level of higher brain function, and evolutionary logic only allows for the possiblity a smarter diet came about as a result of an already-advanced brain. No creature who can't control a fire could ever hope to improve his or his tribe's diet enough to facilitate a dramatic expansion of brain function. Instead, brain function advanced as a direct evolutionary (survival, reproductive) advantage, and things like hunting, fire, cooking and agriculture emerged only as by-products of a brain that could put more and more things together. The answer which cites the article on bone marrow actually proves this point-- the invention of stone tools was a necessary precursor to the addition of bone marrow to the diet; we can see in the animal kingdom today that it takes a brain almost as advanced as ours to use stone tools.
Because we're better at what we do.
Seriously, what does "advanced" mean? Does it mean survival value? Amoebas and cockroaches are more advanced in that regard.
Other creatures are faster, can fly, can swim long distances, are stronger.
Our #1 talent seems to be to fuck up the planet.
So, if God made us, we have to count as a mistake, don't we?
As previously mentioned, the question "why us" from philosophical standpoint is as difficult to answer as any. I think the answer is obviously a result of mutations along the evolutionary chain and an article from Time magizne may shed some light on the "why" and "when" aspect from a scientific standpoint. A team lead by a genetist by the name of Paabo announced that a human version of a gene called FOXP2, which plays a role in our ability to develop speech and language, evolved within the past 200,000 years-after anatomically modern humans first appeared. By comparing the protien coded by the human FOXP2 gene with the same protien in the various great apes and in mice they discovered that the amino acid sequence that makes up the human variant differs from that of the chimp in just two locations out of a total of 715 - an extrodonarly small change that nevertheless may explain the emergenance of all aspects of human speech. It was also discovered that humans with a defective FOXP2 gene have trouble articulating words and understanding grammar.
That we are more advanced than other animals is just an opinion, and to make matters worse, it's an opinion held by those who can be expected to have a speciesist bias.