Paul Smith amended Stephen Black's excellent "evolution forest" as follows:
I would add to the end of Stephen's list a conclusion - something on
the order of
6) and therefore the characteristics of populations change over generations.
I'd also amend #5 to read
5) those which do are therefore able to pass their genes down to the next
generation, and with those genes, some of those variations.
I would like to reduce the list, to get more forest. I would
eliminate (1) below, since it does not seem essential (it gets large
numbers working for selection, but selection can work with small
numbers, it is just more risky).
I would also eliminate reference to genes in (5). Genes provide the
biological mechanism for inheritance of characteristics, but Darwin
did not need then to get to selection.
To me, the forest is really two points, putting them together (among
other things) was Darwin's genius:
1) Organisms vary in many ways that can be inherited.
2) These variations can be selected to produce large changes over time.
This is why Darwin's beginning with selective breeding in "Origin"
works so well rhetorically. Asking HOW selection works gets more to
trees, and thus to Stephen's list.
But then, philosophically I am a "lumper" rather than a "splitter."
-Chuck
Stephen Black's initial list:
1) Organisms produce offspring in large numbers over time
2) The offspring vary in many ways, including (of particular relevance to
psychology), behaviour
3) There is competition within and across species for survival in a particular
evironment
4) Certain of the variations increase the effectiveness of
reproduction in that
environment
5) those which do are therefore able to pass their genes down to the next
generation.
--
- Chuck Huff 1520 St. Olaf Avenue
- Psychology & Computer Science St.Olaf College
- Tel: 507.646.3169 Northfield, MN 55057-1098
- Fax: 507.646.3774 http://www.stolaf.edu/people/huff
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