Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum The Evolution of Evolution

That is the title of a post by Sean Carroll. Actually that is a part of the title. The whole title is "The Evolution of Evolution: Gradualism, or Punctuated Equilibrium?" And the last part of that title is wrong. The article does not discuss the differences between gradualism and punctuated equilibrium. Sean's article can be found on Sean's blog. The article discusses an article posted on Nature Does evolutionary theory need a rethink?. The Nature article is a viewpoint article with discussions between 2 evolutionary scientists who have different viewpoints as to where the theory of evolution needs to go. One viewpoint is that there needs to be an almost complete revision of the theory to take in new points of view. The other viewpoint is that current evolutionary theory already includes them, so there is no reason to make any drastic revisions.

Sean agrees with the second viewpoint although he does admit that he knows almost nothing about evolutionary theory. Having read through the Nature article I agree with Sean. What I know about evolutionary theory says that everything that the first viewpoint is already being researched.

I don't know where Sean got the idea that this is a contest between gradualism and punctuated equilibrium. Those terms are never used in the Nature article and the discussions do not in any way address that argument.

And please everybody. Don't respond if somebody tries to turn this thread into a discussion of Creationism. Just ignore any such replies so that we can carry on a rational discussion if there is anybody who is interested.

Bill Gill

If you want to get wilder try reading works by Wojciech Zurek, that gets right out on the edge

This situation is reminiscent of the “lumper/splitter” divide which is nowhere more evident than in the biological disciplines. “Are these species the same?” has become “Are these processes the same thing?” My guess is that the only way for the two sides to work together would be to agree to differ on terminology.

I’m with Sean and Bill on this one, but that fits with my usual approach to the lumper/splitter situation, which is that I tend to be a lumper, but always want to know why the splitters think as they do.

I'm more of a splitter. That may be influenced by the fact that the author that I have followed the most is Ian Tattersall, who is a splitter.

The thing is that there has been a strong tendency for various species of hominin to develop in relative isolation. I think that the biggest example of this is the difference between Homo Erectus in Asia and Homo Ergaster in Africa. Some people consider them to be the same species and some people refer to Ergaster as an African Erectus. However I don't think they are the same species. It appears to me that some ancestor of both of them, possibly Homo Habilis, migrated out of Africa and made it all the way to Asia. Then that branch developed into Erectus while the branch that stayed in Africa developed into Ergaster. Thus they would have been 2 different species because of the distance between them. That distance would provide a very effective isolation, which is one of the things that is required for speciation.

Within Africa there was plenty of room for speciation as a relatively small population settled in isolated areas where conditions were quite different and could lead to speciation even in the relatively small area of Africa. There are after all a lot of different climatic conditions in Africa. You can expect that members of a given species that move into a different environment would adapt to that environment and eventually become a different species.

Of course as time progressed there was some interbreeding between the various species. This is not unusual. For example it has been some time now since it was discovered that wolves and coyotes occasionally interbred. We haven't lumped wolves and coyotes together into one species yet.

Bill Gill

Lumpers and splitters? However you define it, there is just the one reality. We need quantum definitions, where both views contribute to our understanding of those 'Endless Forms Most Beautiful.'

In the Spring of 2007, I enjoyed Sean's HHMI (Howard Hughes Medical Institute) "Holiday Lecture" on our local 'university channel' as my back recovered from too much fun in the snow.

http://media.hhmi.org/hl/05Lect1.html

Evolution: Constant Change and Common Threads
by Sean B. Carroll, PhD

“What can fossils, butterflies, and stickleback fish tell us about evolution?”

Lecture 1 – Endless Forms Most Beautiful
through
Lecture 4 – From Butterflies to Humans
===

“Welcome to the Howard Hughes Medical Institute; and to our 2005 Holiday Lectures on Science....”


http://www.hhmi.org/biointeractive/explore-holiday-lectures
He's an enjoyable speaker....

~

Thanks for the links. I will need to check out the one on evolution.

Bill Gill

Ok, I watched the first video from the lecture series and it was quite interesting. Fortunately I can take longer breaks between the videos than what the audience got when they were there in person.

I liked Sean's explanation of the differences between the light and dark mice and how quickly the light ones could have developed into the dark ones, even though the odds against any one of the white ones having the mutation that gave them the dark coats was enormous. A very good example of how effective natural selection is in evolving new traits.

Bill Gill