dennis780 writes:
Since Apes have brown eyes, their alleles code for AA (A or a being dominant or recessive traits respectively). Since brown eyes are dominant, and apes are homogenius dominant A, it's not possible for humans to have any recessive colors of eyes, such as blue or green. Even if by random mutation, one member of a primative species (that led to humaniods today) did get a recessive (a), the odds of the offspring recieving that trait is still 0%, as the mate would be AA, and the other would be Aa, leaving only the possibility of AA (50%), or Aa (50%). The offspring (if coded for Aa from the respective mate) would have the same odds, 50/50, but eye colour would still be brown as 2 recessive genes are required (aa).
I don't believe you have thought this through at all. Either that or you are severely lacking in logical skills. You've forgotten to go one generation further.
1. In your hypothetical situation ALL apes have brown eyes and the allele combination AA.
2. You state that if ONE ape has a genetic mutation resulting in a recessive "a" allele that the probability of this genetic variation persisting is 0%. This is not only wrong its HORRIBLY wrong.
EX:
Generation 1: All AA except one mutant Aa
Generation 2: All AA parent pairs produce AA offspring. However, Aa parent produces 50% Aa offspring.
Generation 3: All AA parent pairs produce AA offspring. AA/Aa parent pairs produce 50% Aa offspring. However, if two of the Aa offspring from Generation 2 reproduce together they produce 25% AA, 50% Aa and 25% aa offspring.
So, the 3rd Generation is the first in which a recessive allele mutation could possibly show up. Granted it is more likely that it won't show up in the 3rd Generation but it is inevitable that it will show up. As long as Aa parents continue to reproduce they will produce 50% Aa offspring and so sooner or later the population will have enough Aa offspring for these to reproduce together, resulting in an "aa" offspring.
So, the probability of a recessive gene holding in a population and being expressed is not 0%. As long as Aa parents reproduce the probability of producing an "aa" offspring is close to 100%.
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