From: hartley@maths.uwa.oz.au (Mike Hartley)
Newsgroups: talk.origins
Subject: Re: Evolution implied by the Bible
Date: 9 Jan 1993 11:27:19 GMT
Organization: The University of Western Australia
NNTP-Posting-Host: madvax.maths.uwa.oz.au

mam@jcnpc.cmhnet.org (Mike A. McAngus) writes:

>[ Article crossposted from alt.atheism,talk.religion.misc ]
>[ Author was Martin Dougiamas ]
>[ Posted on Sun, 3 Jan 1993 07:57:20 GMT ]

>Christians among you: explain this.

>If Man was created only thousands of years ago, and we are all
>descended from common stock... why is there such a wide variety
>in our genetic pool today?

I'll present the theory first, and then an example of how the theory
has been applied in modern human endeavour.

The amount of genetic information `inside' an individual can not
be directly inferred from the individual's external appearence.
A person may `have' genes for producing brown hair, blonde hair and
red hair, but that doesn't mean their hair will be stripy.

Now consider an individual who possesses a wide variety of genes
for most of their characteristics - perhaps from the wild. It may
be possible to take this individual, and by selective breeding, produce
a number of other individuals - eg Great Danes and Poodles. How might
one do this?

Say we want to produce a poodle. Take the original dog, and begin to
breed it up. Select those of its offspring which are more `poodle-like'.
So we consistently pick the smaller dogs of the litters. We do this for
several generations, and our `proto-poodles' are getting smaller and
smaller. Suddenly, a dog is born with curly hair. "Wow!" you exclaim.
I'll keep that one! Fairly soon, all of your dogs have curly hair,
and so you continue.

Where did the curly hair come from? The study of genetics tells us that
it was there all the time in the `mongrelised' individuals, but being
a recessive gene, only became manifest under certain (rare) conditions.

Where did the straight hair go? Well, since it's a dominant gene, it's
obviously not present at all in the poodle. (NB - I do not know for
certain if straight hair is dominant or curly hair recessive in dogs.
Nonetheless, the general principles still apply). 

So, we see that the poodle `contains' a lot less genetic information
than our initial dog. Although it is possible, by selective breeding
to so reduce the genetic variation of an individual, it is not possible
to increase the individuals `mongrelisation'. So, if you wanted to
produce a great dane, you should go back to the original stock,
and forget about the poodles. The poodles, so `purebred', may simply
be utterly useless as a breeding stock for great danes, as they may
not have the genetic information for producing (for example) the right
kind of ears, or even for producing the correct size! 

This fact is known amongst biologists. Agricultural Technologists,
when trying to produce "new" species of wheat (for example if the
commonly used ones are suddenly found to be susceptible to 
particular diseases), don't bother with the (readily available) 
`purebred' wheat which is on the general market, but instead
search high and low for the wild (less purebred) varieties, which
are more likely to have the genetic information needed to provide 
resistance to the disease.

Now consider the original stock of a species. It may have a high
degree of genetic variation, but natural selection will tend to
reduce this with time, possibly almost eliminating some of the
dominant alleles and allowing the recessive ones to manifest, 
producing what appear to be new characteristics (Eg - the Galapagos 
finches).

Now if two populations of the same species are separated geographically
(or culturally), then different recessive alleles may become evident
in the different populations, producing two distinct sub-species.
This, it has been shown, can happen quite quickly, and this is how
the different races of man could have occurred.

In the next article, I address the other question asked - what would
happen if the process of natural selection was carried on for millions
of years.

Yours, Mike H...
--
Michael Hartley 		    _-_|\  | "All things works for good to
hartley@madvax.maths.uwa.oz.au     /	 \ |  them that love God - them that
University of WA ----------------> *_.-._/ |  are the called according to His
					v  |  purpose" - Romans 8:28