What's not working yet in the Theory of Natural Selection?

November 6, 2009 5:13 PM

When current/recent SCIENCE challenges Darwin, what does it say? I'm a layman interested to hear what not-Creationist, not-ID, not-paranormal challengers (or boundary-pushers) to natural selection might be exploring these days, explained for general readers…

"13 Things that Don't Make Sense: The Darwin Version!" would be perfect. Failing that, are there any book/lecture summaries, web-sites, authors, etc. out there trying to let the person on the street know what some or any serious-science folk might feel is resisting explanation by, or still not quite fitting into, natural selection as the sole mechanism for the shaping of life forms and the building of symbiotic relationships?

There appear to be plenty of "How it all works" writings; are there any "Here's what doesn't quite work yet" books, chapters, footnotes, etc., either from within the ranks, or from other mainstream scientific disciplines?

Or perhaps: What are the still-unsolved, bleeding-edge aspects of the theory?

Or even: How has the theory had to stretch lately to keep pace with new findings?

Thanks!

posted by dpcoffin to science & nature (18 comments total)

Talk Origins FAQs about evolution has some good starting points on topics like genetic drift, punctuated equilibrium, and a brief history of modifications to the theory after Darwin. (This is not exactly what you are asking for, but a useful adjunct, addressing some common misunderstandings about the supposed controversies within the scientific community.)
posted by LobsterMitten at 5:37 PM on November 6, 2009 [2 favorites]

It sound like you're kind of starting from bad assumptions, or woolly terms. Not sure. Natural selection is not the sole mechanism of Darwin's theory (see artificial selection or sexual selection, for example), and more mechanisms have been found to be significant since Darwin's time, and more are being explored to this day (horizontal gene transfer, for example)

Darwinian evolution is basically a 200 year old understanding of evolution, so there is no shortage of things that were not known back then (DNA for example), but your question sounds like you consider "Darwin" to mean "evolution" and that you're looking for examples of... something (evolution?) for which we don't yet understand a mechanism that would make it possible?

Perhaps start with Horizontal gene transfer? It's a mechanism still being uncovered that explains a bunch of stuff that the selection of heredity traits alone, does not, and Darwinian (ie 200 year old) evolutionary theory was based on hereditary traits. So explains a lot of forms of evolution that Darwin would predict would not happen, but which do happen.
posted by -harlequin- at 5:41 PM on November 6, 2009 [3 favorites]

I thought this talk on TED about the aquatic ape theory was interesting.
I dont think there are any problems for evolution in the sense that- "Heres what doesnt quite work yet". It seems to be more a case of "We dont know exactly how this bit works yet, but there are plenty of possibilities"
posted by phyle at 5:44 PM on November 6, 2009

Or even: How has the theory had to stretch lately to keep pace with new findings?

The theory (or any theory) is constantly changing, being refined, as new evidence comes in. For instance, we've come to realize that evolution isn't a steady process, but rather a punctuated equilibrium in which organisms stay roughly the same until a new selection pressure comes into play, at which point they evolve very rapidly. There are also a number of other factors that play into the origin of species besides natural selection.

There is lots of technical argument in the scientific community about how natural selection works, especially in specific contexts. You can follow these arguments by reading papers in evolutionary biology. LobsterMitten's links are a great place to start, though.

However, the basic idea of natural selection isn't really being challenged. The fundamental idea that species evolve to better adapt to selection pressures is not being seriously challenged by any evolutionary biologist I've ever read. I'm having trouble imagining what the alternative would even be. Natural selection is at the heart of modern biology; you can literally run experiments that show its existence. Your question is a little like asking which mathematicians are challenging the fundamental theorem of calculus. They aren't; they're merely adding to it with new theorems.

If you're interested in historical controversy, there's a whole host of systems that once competed with natural selection, but have since been disproven and supplanted by natural selection and its friends. For instance, Lamarckian evolution, which holds that organisms pass on acquired traits to their offspring--like the just-so story in which the elephant got his trunk after having his nose stretched by a crocodile, which was then passed on to his children.

The only modern challengers to natural selection are from the various magic-based camps you mention in your question (IDers, creationists, etc.).
posted by Netzapper at 5:46 PM on November 6, 2009 [1 favorite]

Just saw this article the other day about sexual selection.
posted by dilettante at 5:53 PM on November 6, 2009

First off, I think there are some false assumptions that you've folded into the basic framework of your question. The theory of evolution starts with Darwin and the foundations he laid down, but our body of knowledge about evolution is much, much, much bigger than existed in Darwin's time. Our understanding of evolution is continually confirmed but it is also expanded and refined by literally too many pieces of evidence to count. Often, new evidence is startling and challenging, and may prompt competing ideas to explain its signficance. Science, by its very nature, accommodates these challenges; it's built into the scientific method.

The most exciting recent news in evolution was the announcement of the discovery of Ardipithecus ramidus, which dates to more than a million years before Australopithecus afarensis (aka Lucy).

Ardi has definitely challenged science's understanding of what came before Lucy. For example, Ardi walked fully upright (without knuckle-dragging), but also had an opposable big toe -- two factors that were not previously expected to coexist in one species at that time. Ardi also had a very small canine tooth (comparable to a modern human canine), rather than the larger, more chimpanzee-like canine that had been expected. These findings were shocking because they indicate that the species was a biped on the ground and a quadruped in trees and that females were evidently selecting for less aggressive males. This is radical for a whole host of reasons, from having to reassess when apes and humans may have shared a common ancestor (it pushes that date back another few million years) to reexamining what the physical geography of Ethiopia looked like at the time (it had been assumed to have been grassland, but evidently it was more arboreal) to reconsidering what social structures may have been like.

None of this, as mentioned upthread, was available in Darwin's time or is mentioned anywhere in anything he wrote. But that doesn't mean that it actually "challenges Darwin" by calling the basic theory of natural selection into question.
posted by scody at 5:55 PM on November 6, 2009 [2 favorites]

I'll certainly cop to wooly terminology, and more than that: I've never struggled so much over framing a question for the green! Finally decided it would make more sense to sort through a bunch of answers than to keep massaging the question, and just let it fly…

"Challenge" seems now a particularly poor choice, since I'm primarily looking for all the ways folks excited by the theory have felt moved or compelled to stretch it, rather than for any more on those who have been and are moved to derail it. But I am also trying to sort out which objections from the challengers have the most force, if any do, so LobsterMitten's first link looks very useful; thanks!

And of course my sense of what "the theory" actually is, is as rudimentary as you might expect from someone who last had it seriously explained to them in mid-20th-Century high school, so I'm certainly not seeking to support or defend any assumptions I may have about the accepted mechanisms of evolution; I simply chose "Darwin" and "natural selection" by default as the best shorthand for my area of interest.

But, anyway; great stuff—thanks! All existing and future comments very much appreciated!
posted by dpcoffin at 6:27 PM on November 6, 2009

Oh, yeah: Bonus points for any audio material; I much prefer to read with my ears these days—the hands and eyes are just too busy elsewhere.
posted by dpcoffin at 6:39 PM on November 6, 2009

Understanding Evolution is a great general resource if you want to brush up on "the theory". As for your original question, you might want to look into epigenetics. Scientists are just starting to explore the link between epigenetic changes and evolution.
posted by jenne at 6:43 PM on November 6, 2009

Well, Darwin was really smart, but he didn't know any genetics, or exactly how heredity worked.

When Mendels stuff got rediscovered, genetics was often seen as being in opposition to natural selection, it took a bunch of people to get them back in alignment in what is now known as the modern synthesis, or Neo-Darwinism. Lots of this stuff eg population genetics, would be quite alien to Darwin, but is still considered Darwinism.

Much of current research concerns specifics - eg how did this specific species form, what is the mutation rate of trait x, how much migration occurs? However, there are still a bunch of unsolved big/philosophical/mechanistic problems in Evolutionary Biology. I've stuck a quick list below, some are reasonably controversial, some are regarded by many as solved, and some are genuinely unknown:

Speciation - How exactly does a species split in two? Can it occur in sympatry, and if so how often and what goes on in the splitting populations? How much gene flow stops it?

Sexual Reproduction- Why does the vast majority of Eukaryotic life use sex to reproduce instead of asex? We have some answers, but they don't make up for the disadvantages at the moment.

Macroevolution - Is macroevolution simply microevolution plus time? If not, what is different?

Punctuation/Tempo and mode - How fast, and how regularly does evolution act over time?

Structuralism - Are organsims constrained in their mutations and response to selection? If they are, does this matter?

Levels of Selection - Does selection occur at the level of individuals, genes, species or populations? Is it a combination?

Co-operation - How does cooperation and symbiosis arise?

Evolvability - Are some organisms evolving to become more evolvable?

Neutrality v selection - what percentage of traits are caused by natural selection versus chance? Is drift a significant evolutionary force?
posted by scodger at 8:25 PM on November 6, 2009 [4 favorites]

Wow, each reply so far has sent me off in fascinating directions and will support weeks of further reading, thanks again. But scodger, you've hit the bulls-eye in terms of my specific question, which I now see should have simply been: "What are the most interesting questions and most persistent puzzles occupying evolutionary theorists these days?" Looking up each of the terms you've used will be exactly the starting point I've been looking for. Any chance you could label your list items Many Think Solved, Controversial, Unknown? And are there any recent lay books that summarize these issues?
posted by dpcoffin at 11:04 PM on November 6, 2009

I'll give it a shot, but won't expect everyone else to agree with me....

Speciation - We have lots of empirical data, here the let down is the lack of workable theory. I think most of it is solved, the big question is the sympatric/allopatric split. I don't know of any lay books in this area.

Sex - The opposite, heaps of theories, little actual data. This is "The queen of problems in evolutionary biology", and unsolved. There are a couple of lay books - The Red Queen by Ridley and Tatianas sex advice to all creation by Judson.

Macroevolution - controversial, little data, very weak theory. Stephen Jay Gould popular writing will have a bit.

Punctuation - Controversial, getting less so. The speed is no problem now, the question is how common stasis is. Again, Gould writes on this.

Structualism - Controversial, and has been getting a big push recently by several groups. Gould again.

Levels of selection - Controversial, consensus is individual and gene only (see Dawkins), with very weak group. There are more than a few who would disagree.

Co-operation - Probably solved in general - see Axelrod for writing.

Evolvability - A little controversial, kind of new field. Not much data either way. Maybe see "mendels demon" by Ridley (skip the last few chapters, they are a bit out there).

Selection/Neutrality - This was long the most controversial field, I am mostly a selectionist and would regard the matter pretty much settled in that court. I know many disagree. Dawkins takes selectionism for granted, a bunch of the Gould/Dawkins stuff was about this question.
posted by scodger at 1:00 AM on November 7, 2009 [1 favorite]

Something I've been interested in of late is the question of just how mitochondria became part of the cell; look into the endosymbiotic hypothesis vs the CoRR hypothesis; fascinating!
posted by nonspecialist at 2:22 AM on November 7, 2009

seconding endosymbiosis (and the work of Lynn Margulis). She's not anti-Darwin or anything, but she opposes the evolution = selfish competition that sometimes gets passed as Darwin's view.
posted by nangua at 6:16 AM on November 7, 2009

You might enjoy The Fossil Trail by Ian Tattersall. It is a history of the science of evolution, so its chronology is derived from the discovery of various fossils and such. It focuses on human evolution, but it covers about 150 years of discoveries, and Tattersall is a good writer and a good scientist, so in general, it makes a great starting point.
posted by carmen at 6:44 AM on November 7, 2009

Now that the selection pressures for physical structure (why mammals have fur, why this species has a longer tail or sharper beak, etc.) have been determined for the large part in a large number of species, a research emphasis is being placed on how human behavior evolved. Cooperativity, reciprocity, fairness, etc. are fairly big hot topics in primatology right now, too. So, how does being nice to a fellow monkey benefit you in the future? Were you better able to make alliances against rivals or superiors in the hierarchy? Do monkeys remember your past good deeds towards them and reward you with better food or better mate choice in the future? Will you be punished if you don't meet expectations of sharing that your fellow monkeys already have? Or is it better to keep that juicy leaf for yourself since sharing will curry you no future favor and everyone else is looking out for themselves, too.

Also, cognition studies on how intelligence evolved are pretty fascinating, especially on dogs. Since they were domesticated by humans and share a long evolutionary history together, they actually understand some things (e.g. visual cues such as pointing) better than the primates that are genetically more closely related. It brings new questions and new light to the nature vs. nurture arguments.
posted by alygator at 6:47 AM on November 7, 2009

Chaos, by John Gleick.
posted by Area Control at 9:07 AM on November 7, 2009

[All answers marked Best]
posted by dpcoffin at 9:52 AM on November 7, 2009