Tom Sawyer

I just finished reading Richard Dawkin's book The Blind Watchmaker. In it, he made a good argument about how macroevoultion is nothing more than large amounts of microevolutionary steps. He said that if an embryo is too different from the parent, it probably wouldn't develop and even if it was born, it probably wouldn't be able to reproduce (it was a lot more involved than that, but that's the basic argument).

He was saying that the opposing view of puctuated evolution, which has large changes happening quickly as opposed to small changes happening slowly was a competing theory of evolution that a lot of people in the field were arguing for. Now, he wrote the book in 1986 and I was wondering if this is still a popular theory (in the view of scientists, not people who don't understand evolution).

Does anyone know what the current state of this idea is?

[ October 15, 2002: Message edited by: peteyh ]</p>

Philosoft

I thought I remembered a chapter in The Blind Watchmaker wherein Dawkins argued that the dichotomy between gradualism and PE was basically illusory; he called the common strawman of gradualism "constant-speedism" and also mentioned the 'short' evolutionary times of PE were much longer than commonly thought.

pz

I have no problems with the general principle of macroevolution as microevolution writ large, but Dawkins is a gene-centric adaptationist extremist who over-emphasizes the role of selection, and focuses overmuch on one level of activity, at the gene.

He mischaracterizes punctuated equilibrium, which is not the "hopeful monster"-style of single-generation transformation described above. PE describes the evolution of populations, not individuals.

I really like Dawkins writing, and I sympathize strongly with his scientific attitudes, but I disagree with much of his perspective on evolution.

Uzzah

pz, to jump off topic real quick..

As a young guy who's now jumping into the finer points and evidence of the more main stream evolution theories, which would you recommend that I pick up? (please, anything but The Structure of Evolutionary Theory ) I'm reading through "The Blind Watchmaker" right now and I can already see, without reading any opposing books, how fellow biologist could oppose some of Dawkin's ideas. Or at least offer equal/better alternatives.


Uzzah

Tom Sawyer

pz,

Could you explain this a bit more, or point me to a good resource that does so?

It seems to me that any change in populations is no more than changes to individuals within those populations. Any mutation that develops would still have to be close enough to the mother so as not to have her spontaneously abort it (when my wife was pregnant, some of the medical articles I read said that that the body recognizing deformities in the fetus was one of the causes of miscarriages). Then there's the whole problem of actually becoming a member of the society and being able to mate and reproduce if it did develop.

Maybe I just misunderstand what the whole idea of punctuated evolution is all about.


Wouldn't any changes have to be on the genetic level? If they weren't, how could they be carried onto the next generation?

pz

Why not? Are you some kind of dilettante?
There is no shortcut. You've got to read a lot of stuff to get the big picture -- this is a complicated subject!

The textbooks by Futuyma or Ridley are good places to start.

If those seem too heavy to start with, you can read some of the more popular texts, like Dawkins. You have to realize, though, that every single one of them is offering a very slanted view, and you really need to read several of them. If you are looking for something to specifically counter Dawkins, I recommend Lewontin. Not only is he a brilliant writer, but he champions a much more pluralistic view of biology. _The Triple Helix_ is a short and easy read, and you can guess what _Not in Our Genes_ is about.

Anything by Mayr is good, but be warned: he is really myopic, and goes beyond just ignoring everything he disagrees with to claiming that he invented it all first.

Gould is also great, but as you've noticed, his magnum opus is this huge, bloated, turgid, horribly written thing. There really is some good stuff in there (especially if you want to get into levels of evolutionary change), but its not very approachable.

Personally, I like some rather radical stuff that emphasizes developmental perspectives on evolution...Raff, Goodwin, Oyama. To be honest, I don't think it's the place to start a study of evolution, though. It'll warp your brain in odd ways and everyone will look at you funny.

For just plain fun reading in the subject, everyone ought to read Zimmer's _At the Water's Edge_ and Weiner's _Beak of the Finch_.

MrDarwin

Our library at work just got in this new book by Ernst Mayr:

<a href="http://www.amazon.com/exec/obidos/ASIN/0465044263/qid=1034710050/sr=2-1/ref=sr_2_1/102-7703683-0041741" target="_blank">What Evolution Is</a>

I've just skimmed it so far. Opinionated, sure, with some stuff I don't entirely agree with, but overall it's gotten good reviews and it looks like a much easier read than Gould's "Structure of Evolutionary Theory", in which I haven't gotten past the first few pages! I'm glad I'm not the only one who thinks it is poorly written; his brilliance could have benefited from a whole lot of editing but I suppose that would have been blasphemy!

Albion

Yes, I agree about Mayr's book. Niles Eldredge also has some good stuff in his book "The Triumph of Evolution and the Failure of Creationism." Glad I'm not the only one finding Gould's doorstop hard going. Bit of a surprise after his other books.

wade-w

Peteyh;

In general, evolution is about populations, not individuals. Even the standard definition is in terms of populations: A change in allele frequencies in a population over time.

The gradualist postition is that enough of these changes in allele frequencies over enough time is all that is needed to explain speciation. On the other hand, PE says that as long as a population remains in a stable environment, we should expect to see few if any major changes. However, when that environment does change, we will then see rapid evolution of the population, or exctinction. Note that "rapid" here is still not meant to imply a speciation event in just one or two generations.

The idea is that if there are suddenly (in geological terms) several new niches available, mutations that may have been detrimental in the old environment may be advantageous in the new, giving rise to new species in what appears from our perspective to be "over night".

Personally, I don't really see a big dichotomy between the two ideas.

RufusAtticus

Peteyh,

There is no debate in the biological community that gradual accumulation of minor differences can account for the major differences between groups of organisms. In the last ten years there has been alot of work on the genetics of adaptation, but it is elaborating on the above statement mpt challenging it.