Razib at Gene Expression has called for a followup to the "evolution in ten words or less" post he previously had and which I responded to (linked in his post above) with a call for "ten assertions about evolution". So I just saw this, and of course I rise to the challenge...
1. All progress in evolution is local. Any longer term trends are either responses to long term environmental changes or stochastic.
2. Natural selection is not evolution (as Fisher said in his Genetical Theory in 1930. Evolution also covers taxonomic diversity, random processes, sexual selection, and so forth.
3. Selection is the general category. "Natural" selection is whatever isn't sexual selection, artificial selection, kin selection, organism selection or group selection...
4. All species are intermediates, either on the way to extinction or new species. There are no "missing links", because all species are adequate to the conditions in which they evolved.
5. All species, including humans, are still evolving. "Evolution" involves both stasis and change. If a taxon is stable over time, that is evolution, because the default is that things will change unless acted upon by stabilising forces.
6. Macroevolution (evolution above the species level) really is just the effect of microevolution (evolution at the population level). But it is skewed in ways we can't predict from populational evolution because we can't predict the topography and parameters of the environment of species over time.
7. Genes are only one element of evolution, and there are other forms of heredity, including locale, that affect evolutionary change. Evolution is not all about the genes, but about the lifecycles of organisms.
8. Human cognition is an evolved trait, but it is not something that evolved once int he "environment of evolutionary adaptation", but is still evolving. We are in our "natural environment" and always have been.
9. Species are "tolerably well defined" as Darwin said, but there is no rank of being a species that is natural. Instead, species are where organismic and genetic lineages tend to coincide, and that is unique in each case.
10. The only natural way to group higher taxa is genealogical. Or, in cladistic terms, taxa above the species level are monophyletic.
That should be enough to call down the wrath of the gods upon me... but I must also make an 11th claim:
11. Biology is about more than evolution.
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I do not disagree with the others' responses, but I like yours the best - where you placed the emphasis.
Yes., I liked yours better too...
But where's Larry? I set out the bait, he has to come and tackle me on the micor-macro thing...
I disagree with parts of point 3. For me, sexual selection, kin selection, organism selection and [trait] group selection are all natural selection, they're just different types of natural selection.
I guess this is just a case of where you want to draw the line. But we all know my way is RIGHT.
Bob
Nice list, John.
Bob, yes, we know "my way is RIGHT", but you're misplacing the indexical here :-)
10 words or less!! Anyway, good job.
5b. "If a taxon is stable over time, that is evolution, because the default is that things will change unless acted upon by stabilising forces."
There's also the point that stable periods allow accumulation of diversity, which will become important the next time things go pear-shaped.
And I'm with Bob O'H: With your definition, "natural selection" gets reduced to an et cetera. The common thread among sexual, kin selection, organism, and group selection (as well as others), is simply that selection pressures "feed back" upon themselves at multiple levels of description. The presence of one's conspecifics (and their behavior) is part of the environment, and if nothing else, Malthusian considerations will come into play. Much the same applies to creatures modifying their environment.
A few minor comment. I am not sure that evolution does not haeve longer term trends. For example, is it reasonable to say that there is a long term trend to building up responses? That is, organism tend to accumlate, sometimes with deactivated genes, mechanisms for responding to some environmental condition.
For 2, how about "evolution is not just Natural Selection"?
For 3, why did Darwin call it "Natural"?
For 7, great point. We look at genes because they are the easiest thing to compare, but some forget that.
John Wilkins asked,
Macroevolution
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I would like you to dig into your #7 in a next post. I am not sure I understand it (well, I 'm sure I rather under stand it).
On #7: There are resources and extragenetic inheritances that are crucial to the development and survival of organisms. For example, ask how fit a gene would be if you move the organism to low earth orbit without a spacesuit. Genes play a crucial role, but they are only part of the wider developmental system, and things like methylation, cytological components (remember the famous Plasmodium experiment in which the cilia were surgically reversed and inherited?), maternal resources like the egg and womb, environmental constructs like beaver dams, elephant paths), and cultural transmits like birdsong, hunting skills, and even distribution all play critical roles in the lifecycles of the organisms.
There is a theory called "niche construction" in which organisms systematically modify their environment to suit them, which is also passed on to descendents, such as the way elephants in savannah conditions keep trees down (literally, by pushing them over) to make the conditions useful. They don't do this intentionally, of course, but the result is that the conditions better suit them.
If you think of the famous Weismann diagram, with somatic properties developing independently of the "germ cells", you might add arrows at all levels above the germ cells to indicate these lines of inheritance.
10 words or less!! Anyway, good job.
Ten words, schmen words! Besides, I leave it as an exercise to the reader to reduce all these to a ten word format...
I like your list John, but I have a few small disagreements.
"The difference between micro & macroevolution is semantic."
To say that you must rule out higher sorting patterns that can make substantial reductions in variation. If something like clade selection exist it would be a factor of a different sort than natural selection. Natural selection must always work locally, and for the here and now. It is reduction of genetic information at a very fine scale. But sorting patterns which wipe out entire groups is a reduction in genetic information at a different
tire. Both are important, but they work together to form the patterns we see in deep geological time. Because this phenomenon has not been ruled out, and is attractive to many evolutionists to explain the trends they observed in the fossil record, it is a little premature to say the differences between micro- and macroevolution is semantic.
And it might also be wrong.
"Selection occurs mostly on the level of the individual."
This is true, but it doesn't inform us how powerful natural selection is compared to other processes of selection. To some people this is important.
"Humans are still evolving."
But in an appreciable way?
Also, organism selection isn't natural selection? Please explain. Best,
Sorry John. My first post should have been directed to Razib. Best,
That's OK. I was going to do a long reply when I realised that I hadn't said these things.
And organism selection is, in my view, natural selection only because in my view all selection processes are "natural". Darwin was trying to draw a distinction between artifical and antural selection, but at different times different thinkers have included or excluded all these things under that rubric. I think artificial selection is as natural as the rest, and it all goes by the same concept of selection processes.
Ugh. How embarrassing. But regarding natural selection, I've always believed that the term was never intended to encompass all selective processes that are natural, but rather was termed so because it was the first process discovered which offered a counter solution to argument from supernatural designthe antithesis. Given this context, I think it is only appropriate that we are not to literal in our reading of the word "natural," and use the phrase only to describe differential reproductive success, based exclusively upon relative fitness, by the nonrandom death of individual organisms. Or something close to that. Umbrellas that are too big don't seem to work very well. Not for me anyway.
No, Darwin explicitly said that he called it natural seleciton in contrast to artifical selection by breeders (such as pigeon fanciers, farmers, and horse breeders). It was not in contrast to supernatural anything, except that it offered a natural "mechanism" that produced the appearance of design.
Wallace hated the term, believing it had voluntaristic implications ("what does the selecting?"), and insisted that Darwin use the phrase "survival of the fittest" (where "fit" meant something like "apt"), a phrase taken from Herbert Spencer's writings.
Language was not devised to deal with agentless design, and both terms were unfortunate. Darwin originally had another phrase ""natural preservation" that he later wished he had used. (Michael Ruse, The Darwinian Revolution, 1979, p208, cf. Darwin's letter on p116 of this link)
John, I must say this is a great post. I really enjoy your thiking here. I am, however with the crowd that says sexual selection, et al is really natural selection in a different wrapper. If you mean, as you did in your last comment about language not being user friendly towards agentless actions and that 'natural' was just a term for 'not artificial' then great.
I would also like to ask a question of Larry.
So, exactly, what did you accomplish with your excerpt that you linked previously? I'm afraid I must admit that my opinion is not swayed by your excerpt. I don't mean this disrespectfully; but I have this sinking feeling that you are trying to get us to buy into the idea that coining the term macroevolution to involve the [incomplete] fossil record is truly unfair and your post offers no alternative explanation to traditional interpretations that macroevolution is just microevolution stretched out over a longer period. Perhaps if you wouldn't have invoked the great Stephan Jay Gould to your rescue you would have been onto something but I find his interpretation that puncuated equilibria is an alternative to natural selection is just too full of holes. Should we not expect that there will be leaps and bounds due to environmental factors? Is this in any way inconsistent with what the neo-Darwinist view is? What could possibly be another solution? Shall we honestly look into saltation? Should we believe Lamarck was correct? Can we invoke GOD? The idea that organisms are vehicles for genes to reproduce accurate copies of themselves is not very flattering. I realize this, but unless you have a better idea (which I'd love to hear), then it is the most accurate description we have thus far.
How stupid of me not to have thought of that! Best,
For Jason. How is puncuated equilibrium an alternative to natural selection? As for Larry, boy, he needs no rescue. Not by Gould, and not by me. He knows what he's talking about. All the best,
Miguel, that is my point
Who ever argued that PE was ever an "alternative" to natural selection? Not Gould, and not anyone else I can recall. PE is a theory about rates, the cohesiveness of species, their stability through time, and possibly their differential success. Other theories such as clade selection, which is supported by PE, are supplemental to lower level selection on organisms. Not in contradiction. No one (except creationists) denies that lower level selection is happening and is fundamentally important. Best,