Humans are driven towards
diversity.
The trend of all physical and biological evolution has been towards greater diversity. The cosmic egg split apart with the Big Bang has diversified into a hundred types of atoms and over three hundred particles, and humans are even finds ways to make new ones. And consider biological development since the origin of life, most likely simple chemical soups in the oceans, to the almost unimaginable complexity of life today. Complexity is basically a function of the number of parts in the system, of the number of types of parts in the system and, most importantly, of the number of relationships between the parts. As the physical universe evolves, complexity increases.
So it is as well with the mind. Consciousness has evolved along with the complexity both of the nervous system of animals and of the animals interactions amongst themselves. We may say that the complex functioning of brains gives rise to the mind. What is mind? Mind is actually a process rather than a thing. A great analogy for the mind is that it is like a sentence: it has a noun and a verb. The noun is memory and the verb is consciousness. This verb's particular action is of focusing attention on internal and external memes (memories and perceptions, respectively) and resolving the system. A resolved, or harmonious system (mind) means a mind that is sane, happy and intelligent. Happiness comes from the gratification of values, some of which are inborn (genetic) but the vast majority of which are environmentally-acquired. An example of the former has to do with my ideal-comfort body temperature and an example of later would be me smiling as I hug my fast, cute iMac. Values are memes, which will be dealt with under memory, below. Concsiousness, the verb, is the holy grail of cognitive science, something which has eluded the explanations of millenia of philosophers and psychologists. The best way that I could put it is that mind attends to perceptions and memory, seeking to resolve impediments to the organism's complete and total gratification (full belly, finding God, you name it). Since consciousness is harder, I'll start with memory first.
Memory is a repository for memes. My head is festering with probably from twenty-five to fifty thousand memes, each vying for my conscious attention. They all bubble in the background of my consciousness, each vying for attention ("vying to be attended to") and wanting to be 'completed'. A meme is complete when it is a coherent thought and it is 'happy'--that is to say, it is at home with the particular environment of memes in that given mind (non-sequitur links: plays well with others, found a happy home), by which I mean it 'makes sense to you'. Memes in any given mind are subject to natural selection (via a slashdot or E2 kind of ranking system) as the organism interacts with others via linguistic behavior, or with the environment through simple perception and action. If enough people tell me that '2+2=5' is a bad idea, eventually this becomes deselected and that particular meme dies in my mind. It ceases to have any influence upon the community of ideas currently residing in my mind. The '2+2=5' meme might find some small econiche in which to dwell, namely in the minds of mathematicians who can imagined curved spaces in which such a proposition might seem plausible and therefore be very fit. Other memes may be extremely fit and enjoy great reproductive success; the meme-complex of monotheism might even be properly considered a virus. If this doesn't make sense, check out Richard Dawkins or Daniel Dennett, who both do a much better job of explaining this than me, and of course start with the node on meme if you haven't done so already. (Here's a The Matrix-type spin: the concept of memes is itself a meme subject to natural selection. If it is to survive, someone must use it to build a complete theory of consciousness. If someone builds a complete theory of consciousness that does not contain the concept of 'memes', it will die.)
So now that we know how ideas can reproduce themselves, what are they? Ideas are conceived in either figure/ground or polar-continuum dualities: self/other, man/woman, light/dark, life/death, space/time and even mind/matter. I believe I can hazard a primitive explanation for this. The fundamental distinction of mind is between the self and the other. The self is more or less the motor cortex and the other is more or less the sensory cortex (I'm thinking more eyes and ears, rather than bellyache). This is a crude oversimplification, like the concept of the triumverate brain, but it may prove to be an accurate fuzzy outline of what's going on. Intelligence progresses as we acquire the ability to make discriminations. As we gain depth perception, we learn to make figure/ground discriminations. Even as this is happening, the neonate is doing 'face dances' with its mother, gaining the first self/other discrimination. As we mature, we ultimately progress to vastly more complex discriminations, such as "Rush Limbaugh is a Big, Fat Idiot." Discrimination is not intended in the sense of racism (although that is such a meme, however noxious), but in the sense of rationality, a ratio. An icon for the essence of rationality would be a person standing, holding an apple in one hand and a lemon in the other. Memes compete for control of our value systems, which in turn guide attention.
As you get more intelligent, acquiring more memes and integrating them into a more functional whole, the capacity for happiness also increases. Dumb people can only enjoy a football game on the most basic level. A guy like John Holland can also enjoy it on the levels of game theory, adaptive strategies, territorial politics and perhaps also as a metaphor for certain social relationships. It's kind of like the old Murphy's Law: "A pipe gives a wise man time to think, and a fool something to stick in his mouth." Smarter people have more potential for happiness, in the sense of potential energy.
So it is with individuals, so it is in macrocosm with evolution. We are being pulled towards greater diversity, increased novelty and hetereogeneity. Perhaps the end of time is a strange attractor towards change. Perhaps human social evolution is on a rugged-fitness landscape that is presently favoring an increase in the number of types of players in the game, consequently increasing the number of possible interactions between players (strategies and executions) exponentially.