Evolution is not Random

[tongodeon]

Twice in the last two weeks, smart people have told me that evolution cannot explain the structure and variation of the natural world because evolution is "random", "chance", or created by "accident", and that complex structure cannot spontaneously arise from random disorder. I think this is not only a pretty common misconception but is the most

Comments

[occlupanid]

i'm glad you're attempting to explain evolutionary concepts, but saying that the effects of an evolutionary pressure are "predictable" is untrue. Same with "directed and ordered", which btw are [=nopleasenosoundsandsobs=] awful buzzwords to use when discussing evolution, especially with people who have to deal with Intelligent Design proponents. Allow me to throw a quick reference to Stephen J Gould's "Wonderful Life" into your direction, it's written better than any rant i can come up with. Evolutionary Pressures are not measurable or predictable, at least not in the way you might measure salinity in an ocean, or even predict a weather pattern.

[tongodeon]

saying that the effects of an evolutionary pressure are "predictable" is untrue

Huh? People are predicting the outcomes of adaptive pressure all the time. "Bees are going extinct because of cell phones." "Raccoons are becoming less afraid of humans and getting better at opening trash cans." Now maybe some of those predictions aren't actually true, but the actual outcomes aren't "unpredictable". People predict stuff like that all the time, and you can verify that kind of prediction with experiment or observation.

Evolutionary Pressures are not measurable or predictable, at least not in the way you might measure salinity in an ocean, or even predict a weather pattern.

I think you mean that the results of evolutionary pressure are empirical, but not always objectively quantifiable. The peppered moth becoming "darker" is an empirical observation, but it's not objectively quantifiable the way that "5% less salinity" is.

[occlupanid]

yes, you can predict stuff. go ahead, be my guest. But no way in hell can you predict the evolutionary outcome of any selective pressure. It's the kind of thinking that assumes that humans are going to have bigger brains because 'smarter' humans are more fit, because that's the "direction" of our evolution. There is no direction, obviously, but that means it is not "ordered" and "predictable".

[swingland]

actually, if anything, the dumber of our species are encouraged to produce more frequently than the classified intelligent ones

[chemicalpilate]

Twice in the last two weeks, smart people have told me that evolution cannot explain the structure and variation of the natural world because evolution is "random", "chance", or created by "accident", and that complex structure cannot spontaneously arise from random disorder.

Those people need to read more about emergent behavior.

[deeptape]

I'm thinking of making video games to teach it.

[spiritualmonkey]

I forget the reference, but someone once pointed out that there seemed not to be cases of evolution moving from more-complex to less-complex beings.

And if evolution could be said to "have a direction", that it was from less-complex to more-complex entities, using the mechanism of natural selection & mutation.

[tongodeon]

someone once pointed out that there seemed not to be cases of evolution moving from more-complex to less-complex beings.

I think it's hard to objectively define what "more complex" or "less complex" means. Even if you take a subjective definition you could still argue that every major extinction event is an evolution from "more complex" to "less complex". And extinction events aside I'm not sure whether life on earth today is significantly "more complex" than it was, say, in the Permian period when oxygen levels were very high and we had dragonflies the size of dogs.

That being said, every year is another year with an opportunity for speciation. If you measure "complexity" as a tally of the number of species on earth then that number is trending up in the long term.

[swingland]

i think more complex towards less complex in terms of cellular structure. a turtle, for instance, is much more complex at the cellular level while a euglena, a far distant predecessor (at least theoretically) is much more simple at the molecular level.

a human may not come up with another opposible thumb, but it will surely not degenerate into a pile of slime mold.

[occlupanid]

no extra thumb, sure. but give any organism enough time, it can neotonize into a blob of jelly.

[occlupanid]

i think the main problem is this false dichotomy you've created:

In all cases the selection is consequential and nonrandom, the exact *opposite* of "chance", "happenstance", or "accident". The selection phase of evolution is based on fitness for survival to breeding age, which is completely nonrandom.actually, they're observable, but they're not the "opposite" of random in the same way that peanut butter is not necessarily the "opposite" of jelly. You can observe selective pressure, but say you're studying plumage-selection in birds. The ones with better plumage mate, and have more kids. You can predict that the brighter ones are "more fit" and therefore 'destined' to take over the island. Except that not all birds are selecting for that. some like ones with not the brightest plumage, but simply are bored and want to fuck. Or they are scamming for other mates. Don't stop there, keep adding selection pressures! Because now the ones with large plumage also have weaker sperm, and are getting the short end of the birthing stick. Then

[swingland]

they do. if all the birds on the island die because of a volcano, then other species move in to fill those birds' roles in the ecosystem

[epileptikitty]

Except for a 'species ring'. If there's a bug living on the shore of, say, Lake Tahoe, genetic drift can happen such that bugs from across the lake cannot breed while all bugs can breed with their neighbors.

It is the exception to the 'tree of life' genetic splitting phenomenon. Doot dooooo-de-doo-doot.

[tongodeon]

Don't worry about species rings just yet. If you've got your knickers in a twist about this, I've got an upcoming post about (among other things) species rings that's going to totally set you off. :)

[madbodger]

Actually, natural selection does include a fair amount of luck. It's more random than is comfortable to think about. We'll end up at various local maxima, but can easily miss bigger/better maxima. And, as the environment changes, the less-adapted creatures will slide around and continue (cf horseshoe crabs), while the most finely adapted ones will perish.