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Does our recent work "prove evolution"?

Many aspects of evolution are already well understood. We have more data on recent events (the last 100 million years or so) than on ancient ones. For example, when was the last time anyone offered a detailed arguement that molecular data on humans and chimps are more consistent with independent creation than with evolution from a common ancestor? But we have much less information about the origin of life and (a billion or so years later), the evolution of multicellular life from unicellular ancestors.

There are thousands of papers on how natural selection and other processes change species over generations, and thousands more on how species split into more species, but far fewer on major transitions: genes uniting into chromosomes, the origin of eukaryotes, multicellularity, and so on. There are even fewer attempts to study such transitions under controlled, repeatable conditions. That's why our recent paper has generated so much interest -- not because it sheds any light on how life arose in the first place.

But some creationist is criticizing our recent paper, on You-Tube. He points out that we used centrifugation -- the lowest setting, but still much stronger than gravity -- to select for multicellularity. If such strong gravitational forces were the only way multicellularity could evolve by natural selection, then we would indeed have to look for other explanations. But regular gravity works, too; it just takes longer. (Longer settling time per selection cycle, not necessarily more cycles.) So does predation, as shown by Boraas et al. in 1998. Certain economies of scale might work, as suggested recently by Koschwanez et al. And resistance to stresses like UV might work, too, as I suggested in an earlier post.

We aren't so much asking what natural forces could select for multicellularity (protection from predators versus UV, say), but focusing on questions like:
* Given strong selection, how fast can multicellularity evolve? (fast! so why did it take billions of years?)
* What genetic changes are key to the initial transition -- are there multiple genetic routes to multicellularity? -- and what further changes occur early in multicellular evolution? (in progress)

To answer the latter sorts of questions, it helps to be able to apply exactly the same selection pressure to multiple replicate populations -- we've used ten -- and that's easier with centrifugation than with finicky predators.

Unlike us, Jesus isn't around to object that "that wasn't what I said." So I do want to point out an apparent misattribution in the You-Tube video:

"Jesus was right about creation, 2000 years ago. I wonder what else he was right about." -- creationist on U-tube

If Jesus said anything much about creation, I missed it, but there's this:
And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward. But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly. -- Matthew 6:5-6

And God supposedly said something about not bearing false witness. Surely attributing things to Jesus that he never said would qualify.

Comments

You can always count on the Kool-Aid drinkers for a good laugh. Though I have to say, that video is one of the more bizarre things I have ever seen.

Looks like you got another creationist's attention:

http://www.evolutionnews.org/2012/01/more_darwinian055511.html

Interesting, the authors of the yeast paper apparently believe that God, in the biggest miracle mankind has ever witnessed, raised Jesus from the dead (since they quote Jesus to defend their position!), yet they believe that processes that degrade preexisting cellular abilities are proof that God cannot create life in the first place?!?

If you want a higher-profile venue, I think I remember Carl Zimmer offering space on his blog The Loom for scientists to address creationist attacks on their work. See, for example, http://blogs.discovermagazine.com/loom/2009/10/15/the-blind-locksmith-continued-an-update-from-joe-thornton/

Jeff,
We will consider. Meanwhile, he's already hosted some thoughtful criticism by scientists, and our replies.
http://blogs.discovermagazine.com/loom/2012/01/18/evolving-bodies-a-storify-follow-up/

Phillip,

I rescued your comment from the spam filter, but cut off your lengthy rant after the first 5 logical errors.

1) Nothing Jesus supposedly said long BEFORE he died is evidence that he rose from the dead.
2) Coming to life after (apparently?) being dead could have various explanations, including Jesus's own alleged miraculous powers.
3) I quoted Jesus on a religious point that many self-professed Christians choose to ignore -- nothing to do with evolution.
4) A better understanding of how multicellular life can evolve from unicellular life tells us nothing about how life first arose.
5) Even if we had evolved life from nonlife, under conditions thought to have existed on the early Earth -- that would be much harder than what we did, but it might be possible -- that would only show that life COULD have evolved without an intelligent creator. It would not be proof that such a creator didn't exist.

You state in your article that you "...observed adaptation of multicellular traits, indicating a shift in selection from individual cells to multicellular individuals" in the clustering cells. However, were the clusters actually more viable opposed to the non clustered ones under the same conditions? This would be, of course, one of the most important requirements for evolution.

Yes. See Figure 2 in the paper.
http://www.pnas.org/content/early/2012/01/10/1115323109.abstract

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