When I watched Avatar for the first time I was amazed, along with the rest of the audience, by the fantastical world that was created on the screen. I saw it twice, and both times after the show I said something about how ridiculously far fetched it was for life to come about in a way so similar to our own, most notably I laughed out loud when the first navi woman came on screen and she had breasts, wearing a bra. But when I expressed my amusement at this fact afterward, both times I saw the movie, I got the same response- "Well of course they would have boobs, why wouldnt they?" Well why would they? Breasts are for mammals, they are mammary glands, so you are telling me that life formed totally separate from ours, evolution followed the same path through random mutations to the genetic code and ended up with virtually the same creature, only blue, that feeds its young through 2 mammary glands on its chest. Well of course, right? Evolution creates the perfect organism through its workings, so ending up like a human is the only way to go, humans are the pinnacle of evolutionary perfection right? Right? NO WAY! Evolution is far far far from perfect, and I dont think I am disagreeing with anyone when I say that humans are also quite far from perfect (except the millions who believe that we are created in the image of god and we are actually what perfection looks like... what a disappointment). Evolution does not always give you the best possible outcome, it can only do so much to make progress. One good example is a nerve in the giraffe, the laryngeal which travels from the brain, all the way down its neck to the heart, around an artery, and then all the way back up the neck to connect to the larynx, without serving a single function anywhere besides the start in the brain and the end at the larynx. This pathway works perfectly fine for our distant ancestors, but the wasted energy and space that the mammalian neck, especially the giraffe, exhibits is an astounding example of the imperfection of evolution. For the record I tried to see if James Cameron, the director of Avatar, had anything to say on the subject, and when he was asked why the Navi had boobs, he said it was because it will be humans that are watching the movie and thats what humans want to see. I am so glad he didnt try to justify it any further than that.
Now I dont want to go on too long about that, I think everyone knows that Avatar was far fetched, I wont even get into the fact that they were relying on the DNA of the Navi to be of the same construction as our own, you know, our inefficient system of ATGC, all coding the same proteins through the same mechanisms... just ridiculous... so ya, I wont get into that. But this did lead me into a more interesting train of thought. When contemplating the imperfection/incompletion of human evolution, I tried to think of a way that the human population was still evolving. My brother said that he thought there was much evolution to still occur, that we will soon overpopulate the planet and bring ourselves to a point where we will be competing for resources and there will actually be a fitness curve for various traits allowing success in such a society. I disagree, first I think that humans posses the intelligence to keep ourselves from getting to that point, and even if we were to reach that point, I think that genetic traits would have nothing to do with our ability to survive. With human politics and such advanced social networks, it is the situation that one is born into that often has the most to do with how their life is lived. Just because one boy is born in a third world country and another is born to an upper class family, does not mean that the genetics of the upper class boy are more "fit" but he will have a better chance at survival.
Could we still be evolving? When looking at the evolutionary fitness of a human individual, ultimately it is the rate of reproduction which determines fitness. You only have to look at: can they have lots of babies. And tell me in todays society who cannot have babies... everyones doin it. I thought for a while trying to think of a trait that still could be evolving, its not like people who are taller reproduce more, or smarter, or better vision, or better athletes, or have better backs... We have all kinds of problems that seem like they would be selected against in a primal kind of society, but with the complex society that we have developed, well, everybody is having babies, we have reached what seems to be a self imposed evolutionary standstill.
There is one factor that I think may be acting on the human population today. Going as much as I can to the heart if the matter, I think there may be one trait that would lead to a better reproduction rate for humans, and that is the ability to reproduce later in life. The human population has extended its lifetime well beyond what we are made to live, like I said, evolutionary standstill, we were made to die in what we now call our middle aged years, and yet the life expectancy is on a constant rise. This changes the oh-so-important reproductive habits as well, as we are now educating ourselves and being taught abstinence and birth control all through high school and college, which, physically, are really our prime baby makin years. The social norm for having children has been climbing right along with the age expectancy as the human body's age of fertility stays relatively even. Now improved health definitely plays a factor in how old a man or woman maintain fertility, but there has got to be a genetic factor as well. This trait, I think, would be selected for in todays society. If one woman can have a child at 47 and the next at 48, it may be a small difference, but thats all it takes to change the presence of a trait in a population, and I think that is a conceivable possibility. So, I guess it doesnt look like anything is going to happen with our not quite fully evolved bipedal anatomy, male pattern baldness is not going anywhere, we are not evolving into a super intelligent race, and sadly the women of the world are not evolving into (i dont know where this idea just came from, but its awesome) a perfect blend of the Jessicas (You know-Alba, Simpson, Biel(,Rabbit?)), but hey, in the future, women could be popping babies out when they are 70 years old, so there is that to look forward to. You know, by that time we will probably be artificially altering the human genome so maybe all of those things can happen... and you know what that means- Jessicas everywhere.