Evolution by accident

[T'ai Chi]

http://bioinfo.med.utoronto.ca/Evolution_by_Accident/Evolution_by_Accident.html

An interesting article.

 

[Ducky]

Nothing you've ever posted under the "Interesting" heading has ever actually been interesting. Perhaps you should look the word up.

 

[T'ai Chi]

Very interesting, IMO.

 

[Mercutio]

From the article:

The "problem" is that writers like Richard Dawkins have made such a big deal about the non-randomness of natural selection that they risk throwing out the baby with the bathwater. A superficial reading of any Dawkins' book would lead you to the conclusion that evolution is an algorithmic process and that chance and accident have been banished. That's not exactly what he says but it sure is the dominant impression you take away from his work.

So, the position being argued against is a strawman, requiring a superficial reading, and even then "not exactly what he says".

Very interesting, to collectors of strawman arguments, IMO.

 

[fishbob]

Very interesting, IMO.

Yeah, your MO is obvious.

 

[Soapy Sam]

Moderately. Nothing new there.

 

[wollery]

I agree with T'ai Chi, I've always thought that "an" is a more interesting article than "a" or "the".

 

[Tsukasa Buddha]

My psychic powers are telling me that this has something to do with the Dawkins part. In that case, I believe the most intelligent thing the author said was:

Perhaps that's what he's thinking. I dunno.

How insightful, .

 

[Hawk one]

Fowl: It was better than the creationist stuff Justin usually links to. Still, what I get here is that the author seems to misunderstand Dawkins quite a bit. Let's take a look at one particular part near the end, where he refers to Gould's "rewind" thought experiment:

I'm one of those who think that the tape will be different every time it's replayed because there are so many accidents and contingencies. This is Gould's point as well, recognizing of course that the experiment can never be performed. Others disagree. Simon Conway Morris (2003), for example, claims that something similar to humans will evolve whenever the tape is replayed. And Richard Dawkins (2004) is, as you might imagine, sympathetic to the idea that many similar things will reappear each time.

Italics are mine.

Basically, what needs to be cleared up here is that there's a difference between similar and same. If I've read my evolution papers correctly, Dawkins (and Wilkins, and most others I've seen) argues not that the same species will arrive a second time. However, they will fill pretty much the same functions as long as the enviroment remains the same too, thus being similar of nature (even while potentially looking vastly different). So, if we were to do that Gould thing, and rewind the tape on sharks (to make one example), starting about 350 million years ago (before any actual shark would have arrived; but their fairly distant ancestors were around at this time) we'd most likely not end up with sharks as we know them today. But we'd quite likely have something that would be a relentless hunter of the sea, built for speed, muscle, and swift killing of most other things it would come across. Perhaps they'd even look quite alike to the actual sharks living in our oceans, but would nevertheless be so far removed in the genetic makeup that they couldn't even begin to think of crossmating. Or perhaps another potential ancestor would get better at it first, and then -that- species' decendants would get to the top position as sea predator.

It seems to me that the author's not realising this distinct difference between "similar" and "same", and also not realising there's more than one way to fill the same niché in nature. And thus, I simply cannot take his conclusions at face value.

 

[Roboramma]

Fair enough, but what other possible pathways could have been followed? If the actual pathway is only one of several million possibilities then why was that one particular design selected? Is there no possibility that it could have been accidental and selected? Isn't it possible that the actual end-product is as much due to the random mutations that occurred as it is due to natural selection?

Dawkins seems to ignore this possibility when he draws attention to the non-randomness of evolution.

Except that he doesn't. For example, here's a quote from The Ancestor's Tale:

The American theoretical biologist Stuart Kauffman put the question well in a 1985 article

One way to underline our current ignorance is to ask, if evolution were to recur from the Precambrian when early eukaryotic cells had already been formed, what organisms in one or two billion years might be like. And, if the experiment were repeated myriads of times, what properties of organisms would arise repeatedly, what properties would be rare, which properties were easy for evolution to happen upon, which were hard? A central failure of our current thinking about evolution is that it has not led us to pose such questions, although the answers might in fact yield insight into the expected character of organisms.

So far, very good. The Kauffman quote asks this question far better than "does evolution happen by accident?" which is almost a meaningless question. Now we have something to talk about.
So let's see what Dawkins has to say. (I'll leave out a lot because it's a whole chapter, and there are of course copyright issues. But I feel it's important that we see what Dawkins actually has to say about this.

How shall we set about answering the Kauffman question? What would life be like if the 'tape' were rerun a statistical number of times? Immediately we can recognise a whole family of Kauffman questions, of steadily increasing difficulty. Kauffman chose to reset the clock at the moment when the eukaryotic cell was assembled from its bacterial components. But we could imagine restarting the process two or three eons earlier, with the origin of life itself. Or, at the other extreme, we can restart the clock much later, say, at Concestor 1, our split from chimpanzees, and ask whether the hominids would, in a statistically significant number of reruns given what life had reached at Concestor 1, have evolved bipedality, brain enlargement, language, civilisation, and baseball. In between, there is Kauffman question for the origin of the mammals, for the origin of the vertebrates, and any number of other Kauffman questions.

He goes on to suggest that such reruns have actually occurred when landmasses separated populations of animals for millions of years. The ways in which marsupials on Australia (and South America) and placental mammals elsewhere did and did not converge give us some answers to these questions.

When I look at these natural experiments, mostly I am impressed by how similarly evolution turns out when it is allowed to run twice... The differences are instructive too. Kangaroos are hopping antelope-substitutes. Bipedal hopping, when perfected at the end of a line of evolutionary progression, may be as impressively fast as quadrupedal galloping. But the two gaits are radically different from each other, in ways that have wrought major changes in the whole anatomy. Presumably, at some ancestral parting of ways, either of the two 'experimental' lineages could have followed the route of perfecting bipedal hopping, and either could have perfected quadrupedal galloping. As it happens - possibly for almost accidental reasons originally - the kangaroos hopped one way and the antelopes galloped the other.

Bolding is mine.

I have a hunch that the parallelism of mammal radiations in Australia, Madagascar, South America, Africa, and Asia may provide a sort of template for answering Kauffman questions for much older starting points, such as the one he chose, the origin of the eukaryotic cell. Earlier than that landmark event, confidence evaporates. My colleague, Mark Ridley, in Mendel's Demon, suspects that the origin of eukaryotic complexity was a massively improbable event, perhaps even more improbable than the origin of life itself. Influenced by Ridley, my bet is that most rerun thought experiments that start with the origin of life will not make it into the eukaryocracy.

Through all of this Dawkins seems well aware (and even to point out to those unaware) there there is contingency in evolution. Some outcomes, some aspects of outcomes, are dependent upon accident and chance. In this way, Kangaroos are not Antelope.
But far more interesting is the ways in which the process drives in the same direction in different trials - convergence (which is talks about a lot in that chapter).

Any typos in the above are of course mine. I apologize for all the quoting. I just feel that it's important to actually look at what a person is saying, rather than attributing ideas to him that he doesn't put forth.

 

[joobz]

I agree with T'ai Chi, I've always thought that "an" is a more interesting article than "a" or "the".

Thank you for the chuckle.

 

[Spindrift]

Very interesting, IMO.

Nearly 10,000 posts and not once do you ever clearly state what is interesting and why it is interesting.

"You keep using that word. I do not think it means what you think it means." - Inigo Montoya, The Princess Bride.

 

[athon]

Nicely argued, Roborama. I'm cursing the fact that my copy of TAT is still in the UK; reading your post only upset me more. There's so much of it I still haven't read. But I also thought the propositions made by the author in the article were somewhat of a misrepresentation of Dawkin's opinion.

Athon

 

[Schneibster]

And, to take Kauffman's question from the other end, I like to speculate about the genetic code, either in terms of using a different set of nucleic acids, or having the trios code for different amino acids (and by "different," I don't just mean rearranging them, I also mean to speculate about using a different set of them). After all, as Kauffman points out in At Home in the Universe, all you really need is a "toolkit" of a certain complexity, and 32 possible codons using 20 possible amino acids is "just about right."

 

[Paul C. Anagnostopoulos]

The "problem" is that writers like Richard Dawkins have made such a big deal about the non-randomness of natural selection that they risk throwing out the baby with the bathwater. A superficial reading of any Dawkins' book would lead you to the conclusion that evolution is an algorithmic process and that chance and accident have been banished. That's not exactly what he says but it sure is the dominant impression you take away from his work.

Oh wait, Merc already said it:

So, the position being argued against is a strawman, requiring a superficial reading, and even then "not exactly what he says".

And Roborama gave an analysis.

~~ Paul

 

[Dark Jaguar]

Interesting Ian, for once could you get to the bloody point instead of just saying "gee this is... interesting... wink wink, nudge nudge". Why do you think it's interesting? There's a start.

 

[Foster Zygote]

I've always been fascinated by the evolution of these two creatures. The ichthyosaur and the dolphin both evolved from terrestrial vertebrates so, of course, they had a very similar starting point even though the former evolved from a reptile and the later from a mammal. But the fact that they evolved such a similar form despite being separated by tens of millions of years apart is quite amazing if you ask me.

 

[Jeff Corey]

Interesting Ian, for once could you get to the bloody point instead of just saying "gee this is... interesting... wink wink, nudge nudge". Why do you think it's interesting? There's a start.

Actually, it's not II. They are two different species that evolved in a convergent fashion to produce about the same level of mentation.

 

[Zygar]

Speaking of convergent evolution, I actually find this article quite interesting.

Although no one would mistake them for dogs, the Siberian foxes appear to be on the same overall evolutionary path—a route that other domesticated animals also may have followed while coming in from the wild.