Re: The meaning of "convergence" in paleo.
Phil Nicholls (firstname.lastname@example.org)
24 Dec 1994 14:55:05 GMT
In article <email@example.com>,
Pat Dooley <firstname.lastname@example.org> wrote:
>>Convergence is defined as a
>>similarity of characters between two species that _already_ share a
>>habitat or way of life.
>I give up. I thought I understood Dawkins explanation
>of convergent evolution but apparently I have missed
>some mysterious temporal dimension that specifically rules out human
>hairlessness as having any relationship with any other examples of
Consider the examples that Dawkin's used. The adaptive radiation of
marsupials took about 70 million years to reach its present condition.
The evolution of the eye in the octopus and vertebrates took hundreds
of millions of years.
The "aquatic phase" of hominid evolution took, what, 2 million years?
Consider that each case cited by Dawkins had (a) contemporary animals
with observable morphology (b) contemporary common environments.
>Convergence is the end result. When it has occurred, the two species
>will share a common habitat. Then they will most likely diverge, carrying
>some of their convergent evolutionary baggage with them.
All you have is morphology and physiology and the interesting thing
about soft tissues and physiology, at least in mammals, is that they
show considerable phenotypic plasticity. You insulate your hypothesis
from fossil evidence or any other kind of disproving evidence.
Philip "Chris" Nicholls Department of Anthropology
Institute for Hydrohominoid Studies SUNY Albany
University of Ediacara email@example.com