s11002144  wrote:

> Like Darwin had written "evolution is an on going process
> and animals that are better adapted to the environment tend
> to survive
>  and reproduce under some favorable conditions".
> Humans have evolved and now are at the peak of complexity
> does this mean that human evolution has sized or that we
> have
> changed the environment so much that we no longer need the
> environment to make the decisions for us.

This is an old and debated topic. My view is that humans are the result
of a natural process, and what we do is a natural process, and so we are
still subject to natural processes. Granted, we may be subjecting
ourselves to *new* natural processes, like exposure to industrial
chemicals, or incubation of disease reservoirs in overcrowded cities
with rapid communication between them, but this is nothing unusual -
*every* adaptation is to new circumstances for that line. There is, for
example, a number of species which are adapting to the results of *our*
activities - we say they evolve, so why don't we say *we* do when we
adapt to our activities?

There is also no guarantee that we can control our fate, evolutionarily
or otherwise. Unintended outcomes mean that we have to adapt or evolve
just like any other species. So calling on our cognitive abilities is no
reason to think our evolution has stopped.

I would take issue with your claim that we are "at the peak of
complexity" for several reasons - first, there is no obvious
*biological* sense in which we are automatically the most complex
species that does not beg the question. If you start by choosing things
one species does better than any other, then that species is of course
going to be "the most complex" - hummingbirds might beat us to all
get-out on metabolic complexity, for example.

Second, there is no sense in which we are now doing what has not been
done by other species before (except culturally, which does not itself
mean we are not evolving, and might even mean we are evolving *faster*
as a result of it). So I am not sure what "peak of complexity" could
mean here. We have around the same number of cells, cell types, genes,
and other measures of many other mammalian species and some frogs, for
example, have many more genes than we do.

Third, there is a persistent but flawed assumption that evolution is
driving ever upwards towards complexity. This idea predates Darwin by
centuries, and is, in the end, a hangover from religious and
philosophical ideas of the middle ages and earlier. There is no final
goal that, once reached, means no further progress can be made, and no
reason to think that species will, for some measure, continue to get
more complex. In fact, Darwin himself first noted many species in which
complexity has been *lost* to increase the fitness of the organisms
(such as parasites and commensals).

Fourth, evolution does not apply evenly to an entire species except in
rare conditions. Local populations adapt to local conditions, and if
there are local environmental challenges, then some populations will
evolve while others remain stable. So a "better" human may right now be
evolving in the deserts of the Kalahari or Gobi, and we will not know
that until their genes take over the human population, or until they
out-compete us for living space and resources.

Fifth, much, if not most, evolution is not at all adaptive, but the
result of random processes known collectively as "drift". This may
increase complexity or it may decrease it without their being any
"reason" for it otherwise. So we should not expect that we will remain
on any plateau we may have attained so far.

Taken all together I must therefore say: that humans *are* still
evolving; that what we do *is* part of the environment (a lot of human
evolution, by the way, is adaptation to the behaviours of other humans);
that only part of the species can be expected to change, based on what
we know of evolution; and that a lot of it is not adaptive anyway and
hence we should not assume there is a trend to increase any trait.
-- 
John Wilkins
"Listen to your heart, not the voices in your head" - Marge Simpson
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