Question about the Theory of Natural Selection and Theory of Evolution

[bunny]

I think its because the bad fruits die (often before being born) and the good fruits live. So there is an inherent bias in the changes that we observe.

[MidGe]

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that's a good point, however i'd still expect to see a lot of crippled organisms walking around from all the negative mutations. Why is that we only really see the good fruits of evolution and not more of the bad fruits if negative mutations are more common?

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Go and spend some time in the maternity ward of a large gynelogocal hospital. I think the number of unliveable monsters being born will help with your blindness or lack of sight.

[pilliwinks]

I wouldn't get too carried away with that list of observed speciation events. None of them show more than a modest level of reproductive isolation as far as I am aware.

If someone does do an experiment in which they claom to have shown clear speciation, I would examine it very carefully indeed, since the numbers of individuals and generations you would expect to require (if nature is any guide), is prohibitively large for multicellular organisms.

Don't get me wrong, every step in the process of speciation, from mild sexual preferences through to complete incompatibility, can be observed. Just not in the lab, and not from start to finish. My recommendation is not to provide more ammunition for the nay-sayers by over-interpreting results.

[tolbiny]

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that's a good point, however i'd still expect to see a lot of crippled organisms walking around from all the negative mutations. Why is that we only really see the good fruits of evolution and not more of the bad fruits if negative mutations are more common?

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1. There are more bad mutations than good mutations, but there are far more Non-mutations than either (or both put together)
2. Animals that reproduce sexually get 2 copies of each gene, if you get a bad copy fairly often the good copy can take over.
3. Hemophelia, siemese twins, tay sach's, albinos- there are tons of humans born with mutations all the time, mutations which would mark them for death in the animal kingdom but you may be able to survive with for years (or even a regular lifetie) as a human.

[tolbiny]

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that's a good point, however i'd still expect to see a lot of crippled organisms walking around from all the negative mutations. Why is that we only really see the good fruits of evolution and not more of the bad fruits if negative mutations are more common?

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1. There are more bad mutations than good mutations, but there are far more Non-mutations than either (or both put together)
2. Animals that reproduce sexually get 2 copies of each gene, if you get a bad copy fairly often the good copy can take over.
3. Hemophelia, siemese twins, tay sach's, albinos- there are tons of humans born with mutations all the time, mutations which would mark them for death in the animal kingdom but you may be able to survive with for years (or even a regular lifetie) as a human.

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I need to fire in a few edits.
1. there are also "neutral" mutations- those which neither provide a benefit nor a detriment under current conditions.
3. I don't know the genetivc basis (if there is one) for siemese twins, just an example of reproduction gone wrong that clearly wouldn't survive outside of humans.

Extra stuff- any major mutation that effects either a sperms abilty to fertilize an egg (or an eggs to be fertilized) or will cause a miscarige will never be seen.

[godBoy]

ok i'm pretty satisfied with those answers tolbiny, just one more..

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Animals that reproduce sexually get 2 copies of each gene, if you get a bad copy fairly often the good copy can take over.

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If this is true, then it explains how an organism with defective genes can reproduce and not pass them on, the other parent would pass on it's uneffected gene.
Has this been witnessed? - how does the child aquire the good gene 'fairly often'.. more often than not?

[tolbiny]

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If this is true, then it explains how an organism with defective genes can reproduce and not pass them on, the other parent would pass on it's uneffected gene.
Has this been witnessed? - how does the child aquire the good gene 'fairly often'.. more often than not?


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You have 2 copies of every gene, one you got from your mother and one from your father. Each of your children will get one of those two copies at random, and thier other copy will come from thier mother (assuming your male)- so if you have 1 defective copy out of your two genes then each of your children have a 50/50 shot at inheriting that particular copy.