[b said:
Quote[/b] ]We have PROVEN evolution? How? When?
Oh, years and years ago, long before any of us were even born.
Evolution = change in allele frequency over time. This has been observed many, many, many times in the lab and in the wild, to the point that doubting it occurs is just stupid.
Natural selection = unequal propagation of genotypes. Once again, this has been observed so many times that claiming it does not exist is ridiculous.
Speciation = the separation of gene pools. Not as frequently observed, but still common; scientific discoveries of new species evoling from existing ones are now so common they're relegated to 3rd rate journals. It's so common it's boring.
Adaptation (noun) = a variant of a trait which confers a fitness advantage over alternative forms of the trait. Again, so common as to be dull.
Adaptation (verb) = the spread of an adaptation by natural selection. Again, dirt common.
What all of this boils down to is Gould's famous elaboration that evolution is both a fact
and theory.
The fact of evolution is the process we see going on around us in nature and in the lab. The theory of evolution is the mechanisms we use to explain what we see (heritable fitness variations spreading through a population). The fact of evolution is "The allele for such-and-such disease resistance has spread through frog population A...", while the theory is "...because the allele conferred a heritable fitness benefit and thus was acted upon by natural selection".
It's like gravity. There's the fact of gravity (I drop things and they fall according to certain equations) and then there's the *theory* of gravity (gravity is caused by deformations in the space-time continuum / by gravitons / by superstrings). One is the fact, the observable occurence, the other is the explanation, why that occurence happens in the first place.
I would like to note, with no small degree of satisfaction, that due to the failure to produce a Unified Field Theory and the impending demise of M-theory, we actually have a better understanding of the theory of evolution than we do the theory of gravity.
To repeat: we are more sure of the mechanisms by which species evolve than we are of the mechanisms that keep you from simply floating away.
[b said:
Quote[/b] ]Since we do not know the full workings of how DNA functions, we cannot fully understand the minute workings on evolution. Like Mokele said manipulating one gene can affect manydifferent things. Since one singel gene can affect expression on one or more different genes, and different combinations can affect many different aspects of developement. So realy all a mutaion had to do was change one gene and Bam everything falls into place for the cilia motor to be formed. Then that gene is kept because it helps the species like natural selection says.
While that is possible, actual empirical evidence points to a different mechanism: exaptation.
Exaptation is the process by which a trait, formerly selected for one reason, becomes 'co-opted' into a new task and is selected and modifed to those ends.
The bacterial flagella is actually an excellent example of that: we have an intermediate, and it's not a flagella - it's a toxin-injecting device. These devices are built with *mostly* the same genes, in *mostly* the same pattern as the bacterial flagella, but serve a totally different purpose, boring into other cells to kill them, so the bacteria may feast on the remains. there are numerous stages of this toxin pump. It appears that what happened was that bacteria evolved a boring needle, but then mutations allowed it to become a propulsion device.
[b said:
Quote[/b] ] It makes sence that the neadertals didn't die out like previously expected. They were stronger and taller than other humanoids of the time, and just as smart. There brain sizes and the fact that they also used tools points to that. It never made sence that they would have just died out. According to a show on cavemen scientist now believe they didn't die out, but intigrated with homo erectus ( I sure hope that was the correct species. Anyway I think you get the jist of what I am saying)
Actually, it's throught they merged with our own species, Homo sapiens. Also, their intelligence is still up for debate: the total brain volume was larger, but they had a smaller frontal lobe (thinking) and larger occipital lobe (vision). Better hunters, perhaps, but unlikely much smarter.
[b said:
Quote[/b] ]ALso there is a difference between apes and monkeys too. Just FYI We are not related to the spider monkey and other monkeys. We are related to the great apes like erangatang(sp) and gorrillas. They just took a different road on the evolutionary path.
Technically speaking, all life on earth is related; it's just a matter of how closely. But you're mostly right.
Humans are most closely related to chimps & bonobos, then next gorillas, then orangutans, then gibbons (the 'lesser' apes). The apes as a whole, including us, are most closely related to Old-World monkeys, and the combined group of Apes & Old World monkeys is most closely related to New-World monkeys. From there on it's the various prosimians such as lemurs, aye-ayes, potos, and that lot.
That was annoying to type; one of these days, I'll invent some sort of Java code or something that can automatically generate phylogenetic trees that can be posted in this manner.
Anyhow, if you want to prove evolution yourself, send away for two sets of fruit flies; white eyed and red-eyed. Start with an equal mix. Every generation, kill half the red-eyes. After many generations (which, in fruit-fly terms, is about 2-3 months), you'll have only white-eyed flies. Even if you start with 100 red-eyes to 1 white-eye, the result will be the same, though it'll take longer. That's all evolution is; the animals with genes that promote survival (or avoid death) breed more, and become an every-increasing part of the population.
Mokele