First, Vega:
It comes down to statistics!! Depending on who you talk to, the universe is 12 to 15 billion years old. Humans have only been around for 40,000 years. We really are the new kids on the block. It would just be too tough a pill to swallow to believe that nothing else has evolved in all that time and space
My point is one that you touched on in your final paragraph in this post, but I'll humor myself and make the point anyway; the series of events that took place which allowed for us to be here are indeed quite extreme. Today's estimate puts the number of ELEs (Extinction-Level Events) at 5. That means that there have been five major events in history that have wiped out such a significant number of species on this planet that they make all other extinctions seem subtle. And some estimates put the number at six, while some say that we're in the middle of one right now.
360 million years ago, over what most scientist believe to be a course of as many as 20 million years, 70% of all species on Earth died. 251 million years ago, the worst Earth extinction took place, killing almost all (96%) of marine species, and 70% of all land species, including plants, insects, and animals. And the most famous one by mainstream standards happened 65 million years ago, when all the non-flying dinosaurs died.
So you have to think that our prehistoric ancestors had to survive these events, and evolve from them. The chances of that happening are staggering. I'm not going to say that it can't happen elsewhere, because it did in fact happen here, but I won't immediately say that it isn't a fair assumption to believe that every possible intelligent race in the universe is older than us.
Projects like the Kepler Mission and the new Allen Telescope Array, located near Mount Lassen, California, which will enable astronomers to survey 100,000 stars by 2015, should increase the odds of finding a radio signal broadcast by alien life.
I think that what's hampered our finding a radio broadcast from an alien species isn't technological inferiority, but the idea that if there are intelligent species out there, they aren't anywhere near us. I think the chances of finding a neighbor are small...very, very, very small.
Some believe that it takes very special conditions for intelligence to evolve. The late Stephen Jay Gould, the preeminent Harvard University evolutionary biologist and paleontologist, wrote that the creation of intelligence was a freak occurrence, requiring a number of specific events to occur that could never be replicated again.
I don't think it won't (or hasn't) happened again, I just think that we're looking at it backwards. We're these "new kids" in the cosmic block, as you put it, but the fact is that just look how long it took us to get here. I don't think it's fair to assume that just because our species is on 40,000 years old or so, that we're late bloomers, so to speak. Perhaps we're the exception, rather than the rule, or maybe we're one of only a few special cases in which a species managed to survive the cataclysmic event chain that killed off everything in their way. It's not, for me at least, hard to believe that we're special.
Now, Oniw17
Ok, other planets capable of sustaining life naturally, by our standards.
Yeah, well, that makes more sense.
Yes, I know what symmetry means. Please don't insult me. It's possible that, with all the variation to Earth that is likely on the seemingly infinite planets out there, symmetry woul be absent on at least a few of them
Well, I'm not so sure about that. The reason I freaked out about this comment was because symmetry doesn't seem to be one of those luck-of-the-draw things (such as our existance) but more of a thing that suits life as it's needed. Most animals are symmetrical in one way or another, even if the symmetry lies on the inside, and that says to me that symmetry isn't one of those rare occurances, but rather one of those things that happens because it helps. Like, in Humans, for instance, it is said that our facial symmetry is a good sign of freedom from disease, which would make us suitable for mating, thus it serves as an attractant to potential partners.
I just don't understand why you'd think something like symmetry would be absent. In the cases on Earth where there is no symmetry, such as the the Sea Sponge, it seems to be because there is no apparent need for it. They lack real tissue, and have no muscles or internal organs. They lack a circulitory system, and can reproduce both sexually and asexually. So, in every sense of the word, there is no use for symmetry in them.
It's easier to walk when you have two, four, six, eight, twelve legs on each side, rather than 10 legs on one side, and 2 on the other. That is why symmetry occurs, and that's why I would guess that it occurs anywhere there is life.
JD
