I agree that there is such an appearance but I am not sure if this is a necessity for the theory of evolution.
Tim: <<Now, John and most other biologists think that life did develop "naturally"
via evolution. They also think that the complexity of some lineages of
organisms have increased. Thus it is legitimate to say that evolutionary thought does
embrace changes in biological complexity. How this occurs or whether is in an
intrinsic "drive" of life remains an open question. This is also complicated
by the fact that one can't look at a newt, a human or a lungfish and make any
sort of a case for which is the most "complex". Much of evolution does not
seem to have involved sustained increases in complexity.>>
A good point
Tim: <<I do agree with you that it is wrong to say "evolution predicts all species
_must therefore_ display individual increases in complexity over time." That
would be a bogus statement.>>
We agree here.
Responding to Andrew
> Andrew: <<Sick-cell anemia is caused by a loss of genetic information that
> instruct blood cells how to form.>>
>
> Please explain what genetic information was lost? Perhaps you are trying
> to say that "information was changed"? [...]
Tim: <<Well, now that's three times in the last month I've heard sickle-cell anemia
associated with complexity loss -- But it doesn't really count because someone
said it twice... Unfortunately the biochemical details still aren't there,
are they?>>
I would love to see those details as well.
Tim: <<This is for Andrew: The HbS mutation produces a change in the way hemoglobin molecules associate in the red blood cell. It sometimes "stacks" or "crystallizes", leading to the sickled shape of the RBCs. Given that this is a "new" or novel thing for hemoglobin to do, couldn't we likewise make a case that this is a positive increase in complexity? How do we quantitate the change in overall complexity here?>>
Again very good questions that deserve an answer if one is to make the argument that complexity has decreased.
Tim: <<Let's try this from another angle: In malaria-prone environments, there is actually positive selection for maintaining the HbS allele in human populations. In fact, the selection balances in such a way that both the "wild-type" and HbS alleles are maintained in the population. Thus _two_
distinct alleles are retained whereas in normal populations there would mostly be the one wild-type. Which is more complex; an organism with the same copies of a gene or an organism with two different alleles?>>
Ouch, that is a good question.
Tim: <<If you can answer any of these questions, please respond with some details
-- Because I certainly don't have a clue.>>
And neither do I. But given the fact that Andrew's argument is based on understanding this in further detail I am hoping that he has some answers.
Pim