16 Feb '13 23:39>
Originally posted by OdBodThe evolution of the human eye serves a useful sensory function. But consider that
I believe it involved slow incremental changes similar to the development of a complex eye .
the building of such a complex mechanism could inevitably influence the generation
and formation of other organs.
We tend to think of genetics as compartmentalised. The eye evolved like this, fingers
and thumbs evolved like that. However.
We now know that neighbouring genes are able to regulate each other and indeed
local, non-coding sequences can also have extensive influence during
transcription.
For examples sake, people who have folds in their ear lobes are more likely to
suffer from heart disease as the genes are co-located.
Slow, incremental changes may weadle down the alterations made by positive
selection or, if they are of no consequence, they may remain.
Considering this scenario. On the one hand an increase in the number of sweat
glands may serve a directly useful function (greater cooling
ability) which may have been selected for.
On the other hand stronger, thicker hair may have been positively selected for
by sexual preference or social trend and an increase in sweat glands having either
an additionally useful purpose or not making enough of a difference for negative
selection to occur.