Because mutations are random. This is so, because nobody knows what future holds and which feature may be an advantage in different tomorrow's environment. May be climat gets colder - then more feathers become advantageous feature. But may be warmer - then vice versa, the mutation with less feathers will survive more. This, by the way, rules out any divine intervention with mutations - no "directional" mutation is beneficial for survival because of unknown future.

Now, because mutations are random, from time to time they produce wierd organisms, organs, anatomy, wierd brain or shifted sexual orientations. Human brain is especially voulnerable to mutation changes because it is controlled by about 5x10^4 genes - more than any other organ of any other organism - just because it is a complex organ. So, low probability of mutation in one gene is multiplied by number of genes. Thus, brains can be very different, and some of them may have very wierd set of priorities. Thus lesbians, gays, killers, alcoholics, poligamists, etc

Blindness of evolution is seen in many wierd features among animals and even primitive life. Harmafrodite is one example, spider mates eating each other after mate (thus eliminating future matings and thus decreasing amount of offspring) is another. Viruses or bacteria killing their host and thus killing themselves is one more example of blind evolution.

Basicly, evolution does not care - it is completely random process.

• Maybe you can help me, Alex - stormcrow - July 9, 2001 - 18:44 UTC
  • Throwing paint on almost perfect Mona Lisa portrait. - alexander - July 9, 2001 - 19:15 UTC
    • Pollock's paintings evolved - yanniru - July 9, 2001 - 23:22 UTC
    • Clarification - harvey1 - July 10, 2001 - 19:22 UTC
      • Thanks a lot for correction. - alexander - July 10, 2001 - 20:18 UTC
  • We don't know - harvey1 - July 9, 2001 - 22:06 UTC