So I've been thinking about the human body in terms of evolution and natural selection...
I believe in evolution to some degree - and some would say I've got my own distorted ideas about evolution and natural selection/survival of the
So this sums up Natural selection (according to Darwin), right?
Or in short Natural Selection is the differential reproduction of genotypes.
BUT for natural selection to occur, two requirements are essential:
There must be heritable variation for some trait. Examples: beak size, color pattern, thickness of skin, fleetness.
There must be differential survival and reproduction associated with the possession of that trait.
Unless both these requirements are met, adaptation by natural selection cannot occur.
If some individuals are fleeter than others because of differences in their genes, but the predator is so much faster that it does not matter, then no
evolution will occur (e.g. if cheetahs ate snails).
In addition, natural selection can only choose among existing varieties in a population. It might be very useful for polar bears to have white noses,
and then they wouldn't have to cover their noses with their paws when they stalk their prey. The panda could have a much nicer thumb than the clumsy
device that it does have.
When we incorporate genetics into our story, it becomes more obvious why the generation of new variations is a chance process. Variants do not arise
because they are needed. They arise by random processes governed by the laws of genetics. For today, the central point is the chance occurrence of
variation, some of which is adaptive, and the weeding out by natural selection of the best-adapted varieties.
So, the question is, is the human body really the "perfect design" to survive and to be the top of the food chain?
Don't get me wrong; the human body is really an extra-ordinary design with some amazing features. But there's so many "flaws".
For example why do we only have one set of teeth? Why not grow a new tooth when you loose a tooth like sharks? Back in the cavemen days they probably
had bad hygiene - so by 60 they probably had little teeth left meaning you could only eat soft food.
And while we're growing new stuff, why not the ability to grow a new limb like a lizard grows a new tail? If we came from the same gene pool -
millions of years ago - then we should have had genes like that? If you lost a limb back in "the old days", your chances of survival became even
The human body is extremely fragile, and our only defence against predators is brawn. Is that it? Was our ability to adapt and think creatively the
only thing that saved the human species? If we grew poisonous tails like a scorpion to survive would this mean that we wouldn't have been so
"smart"? And why are we so susceptible to diseases? Our immune system is quite weak compared to other animals - like dogs, crocodiles, roaches, etc.
How did we survive this long? The planet wouldn't have been this densely populated if it wasn't for modern medicine. Look at HIV/AIDS. Look at how
it's wiping out our species just because we can't find a cure. Back in "the old days" they didn't have any cures for illnesses like leprosy,
pocks, etc. It's an endless list. BUT we survived all of that somehow. Why wasn't that survival mechanism kept in our immune system?
And when we "mutate"/evolve, we evolve the "stupid ability" to digest milk into the adult years, i.e. some humans became lactose tolerant. We
don't need milk to survive! There are plenty of people making it on a day-to-day basis without milk.
Dolphins and primates are generally accepted to be quite intelligent with some sort of self-awareness. Yet their intelligence is not even comparable
to ours. They have other methods of survival... Would they some day be at the same level of humans?
So, is the human species really based on natural selection and/or evolution looking at its ability to survive - without looking at our ability to
[edit on 14-10-2005 by Gemwolf]