Evolution Can't Go Backward

[Richard D]

I have no idea how they explain teabaggers.

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Evolution Can't Go Backward

Jeanna Bryner-Senior Writer
jeanna Bryner-senior Writer

Wed Sep 23, 4:36 pm ET

In a kind of evolutionary bridge-burning, once a gene has morphed into its current state, the road back gets blocked, new research suggests. So there's no easy way to turn back.

"Evolutionary biologists have long been fascinated by whether evolution can go backwards," said study researcher Joe Thornton of the University of Oregon's Center for Ecology and Evolutionary Biology and the Howard Hughes Medical Institute. "But the issue has remained unresolved, because we seldom know exactly what features our ancestors had, or the mechanisms by which they evolved into their modern forms."

Thornton's team solved this problem by looking at evolution at the molecular level, where they could figure out the steps taken between the ancestral form of a protein and its successor.

Their results, detailed in the Sept. 24 issue of the journal Nature, reveal that over long time scales certain genetic blockades arise that make it nearly impossible to transform a modern protein into its ancestral state, even if ancient environmental pressures were to exist.

"This is the best demonstration of the molecular foundations of evolutionary irreversibility that I have ever read," said Michael Rose, a professor of ecology and evolutionary biology at the University of California, Irvine, who was not involved in the current study.

http://news.yahoo.com/s/livescience/evolutioncantgobackward

[BlooInBloo]

1. Sigh. Evolution isn't goal-oriented. There's no such thing as forward/backward....

There are only people around who assign such terms in retrospect.

And if the environment changes sufficiently, there are no a priori limits on what the long-run results of evolution can be.

[MrModerate]

4. Good point. But what they seem to be saying is . . .

even if conditions return to the "environmental reverse" of what drove the original change (I know I'm oversimplifying grossly), adaptive mutations would not lead to recreation of a previous protein. Even if the form or function that was successful previously were to emerge, it wouldn't be the same biochemically. And in actual fact would probably be an entirely different solution to the problem.

[Johonny]

9. I think the language used in the article is correct

I think you are confusing it with higher and lower life forms. That is generally frowned upon.

You had ancestors back wards in the past and potentially forward in the future. They will all have molecular coding to make proteins. The authors are making an argument as the potential for a future form to regain the ability to make a previous version of a protein an ancestor had. Their argument is the mechanisms of evolution on the molecular level make this unlikely. The articles finding are arguing that on the molecular level there are a priori limits on the long run results of evolution. Their finding basically argue against your criticism.

[Evoman]

11. THANK YOU.

One of my biggest pet peeves. Even pisses me off when I see the term "reverse-evolution" in journal articles. It's sloppy. Use "ancestral" and "derived" if you must, but the sort of language we use is too important to get sloppy like that. It's one of the reasons there are so many ignorant ideas about evolution, even from people who profess to "believe in it."

[Johonny]

15. yeah cause I was only able to find 10 uses of the word ancestral

or ancestor in that article. I could see how someone might get confused reading that article what they meant by back wards. Did you even read it?
:eyes:

[lapfog_1]

2. The theory of Adaptation in Natural and Artificial Systems

environments select survival characteristics of presented individuals. Genetic mutation provides variation in the presented class. The environment can change dramatically from generation to generation and, thus, entire kingdoms of related species can be de-selected for survival.

There is no "forward" or "backward" or even preferred survival characteristics. What might have been selected for many generations (like intelligence) might be de-selected when presented with a different environment.

[Sebastian Doyle]

3. I disagree

Evolution CAN go backwards.........

[eShirl]

5. OK, but I won't ever give up my Devo!

http://www.youtube.com/watch?v=5cmZ62v0t-Q

They tell us that
We lost our tails
Evolving up
From little snails
I say it's all
Just wind in sails!
Are we not Men?
We are Devo!
Are we not Men?
D-E-V-O!

We're pinheads now
We are not whole
We're pinheads all
Jocko Homo
(etc)

[ejpoeta]

6. are you sure?? because there are a lot of idiots with signs that sure seem to be trying.

[caraher]

7. Are they trying if they don't believe in evolution?

But this finding suggests that, if they did not have apes as ancestors, their descendants stand a better chance of being apes themselves, right? ;)

As for the actual science, it makes a lot of sense to me. For the finding to be surprising there would have to be only a very tiny number of sets of genes that were adaptive for a given environment. I'd speculate that there would be many possible genetic codes that were well-adapted to a particular environment for an organism, and simply because an ancestor of an organism once used such a code doesn't make it especially likely that the chain of mutations that occurred in the interim would be "undone" (because one would not expect molecules to have "memories"). In fact, I'd be shocked by the opposite finding; I'd expect it to be possible to "reverse" evolution in the sense of having a series of historical mutations occurring again in reverse chronological order but incredibly improbable, with only a somewhat higher chance of all those "inverse mutations" happening in any order but within a short time.

I think of it this way - if one could calculate the "fitness" of a each set of genes for a given set of environmental conditions you'd have a function on a very high-dimensional space, where a species occupies some small volume of that space corresponding to high fitness. When conditions change, the function is different, and evolution results in a species whose genetic code occupies a different region of that same space. If conditions change back, there's no trail of metaphorical bread crumbs to follow back to exactly that same region; evolution only guarantees that the population will wind up in a region of high fitness, not necessarily the same one.

If there were truly only 1 workable way to adapt to a given environment the result may be different. Though that would also probably mean transformations into that kind of environment would likely lead to exctinctions rather than successful adaptations. My hunch is that most livable environments will have many "solutions" to choose from.

It does sound like the result of the research is saying something stronger, that the odds of retracing evolutionary steps are even lower than chance because there actually may be, in effect, a kind of organismal molecular memory that blocks return. That's a little surprising to me. But the "no backtracking" result is not.

[sofa king]

8. I guess that's why we can't grow gills.

I've always wondered about that: both dinosaurs and mammals had species that returned to the sea and eventually became entirely aquatic, but none have ever regained the ability to collect dissolved oxygen from water, as do fish. I guess because it's an entire system that has been since replaced by other entire systems.

Do I sound like I'm on the right track?

[Johonny]

10. Well there's an advantage to breathing air

The concentration of O2 in the air is much greater than water. Large air breathing animals have dominated the Ocean and shallow seas since the Triassic.

[sofa king]

13. So there's that, too.

An air-breather has higher energy levels and can sustain output longer, right?

[laconicsax]

14. Yes. n/t

[sspeilbergfan90]

12. I agree

[Jim__]

16. Interesting. The one argument that I thought IDers might make ...

... to justify their claims that microevolution exists but not macroevolution (I know the argument is bullshit) is that evolution was cyclical. Otherwise, the result of small changes over long periods of time will add up to a large change, e.g. macroevolution. Looks like that would be a tougher argument to make now.