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| We came, we saw, we conquered natural selection. |
"We stopped natural selection as soon as we started being able to rear 90-95% of our babies that are born. We are the only species to have put a halt to natural selection, of its own free will, as it were," he tells this week's Radio Times. [source: The Guardian]I think a lot of these conversations come about because people like to ask people like David Attenborough (and even me!) what will happen to us in the future. And instead of saying that it's impossible to predict the future of evolution (because it depends on so many probabilistic, seemingly random, and maybe truly random events, big and small), many public intellectuals please the crowd by offering some kind of speculation. Often the questions are about whether we'll grow tails or larger brains; whether our brains will shrink because of computers; whether our wisdom teeth, pinky toes or appendix will completely disappear. And often the experts play along with tongue in cheek, or sometimes seriously, building future scenarios.
The problem with Attenborough's answer--which might be aimed at avoiding this sort of speculation about the future--is that natural selection cannot possibly actually stop, not even at the hands, the hearts, the minds of humans. We're pretty amazing, but not that amazing.
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| Jeepers. What are we even looking at here? (source) |
But natural selection also explains how we are here, alive and working well enough to be here, alive. In that sense, in its purifying sense, natural selection's at work, if you will, on practically everything about us and on practically everything about everything else that's alive now or that's ever been alive. Natural selection is always happening. Always. Culture or no culture... and because of culture!
Furthermore, even if we could consider all environments (and our cultural abilities to adapt to them) to be equal and constant, there will always be both new combinations of old genes and new mutations in each and every person (100+ brand new base changes to each person’s code compared to mom and dad)--some of which will cause human lives to end before they've passed on those combinations and those new mutations.
That each of us is unique, demonstrates that evolution is always occurring even though scientists prefer to think of it as change over time at the population level. Regardless, and this is very important, natural selection allows for most of this perpetual change in lineages and in populations, which is why so much life on the planet is humming and thrumming away, and has for the last 4 billion years.
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| http://evolutionpsa.tumblr.com/ |
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| Teddy Roosevelt conquering a moosevelt. (via @HistoryInPics) |
And it may be true that the odds are greater for any one human to produce offspring that go on to bear their own offspring than for an individual in another, and maybe many many other, species—those that are, arguably, more vulnerable to nature red in tooth and claw.
And it may be true that because we birth relatively few offspring--compared to, for example, octopuses that bear thousands and thousands at once--that there's not a whole lot of difference between Alex's fitness, having 3 kids and 3 grandkids, versus Alice's having 3 kids and 2 grandkids.
And furthermore, it may be true that compared to innumerable species, we have more lineage continuance and less lineage extinction due to fewer juvenile deaths per birth thanks to opposable thumbs, throwing ability, weapons, medicine, extended family, extended love, extended memory, food storage, food production, cooking, sanitation, and so much more that contributes to or falls under the “culture” umbrella.
Classic examples of recent and potentially currently occurring natural selection that people call on in discussions like this are lactose tolerance and malaria resistance. Both are usually used to argue that natural selection has not stopped. But leaning on them can give the impression that we know of only two ways humans are presently adapting. There are others, like amylase and immune system genes, which are potentially powerful too, but again, examples of human biological adaptation in present or near-present times are not exactly overwhelming us. No matter! Because there are, unfortunately, myriad mutations (individually rare, but not so rare in total), both de novo and inherited, that are selected against every day, all around us, too numerous to list. This is natural selection.
So it's just wrong to say that natural selection has stopped unless to "stop" is a relative term. And even then, saying natural selection has relatively stopped or has effectively stopped in humans is making an assumption about what's good for humanity (that will sadly never evolve) and what's bad (that we're so busy propagating). It's also making an assumption about the relative strength of selection for forming adaptations out there in the "wild"--one that isn't grounded in firm understanding or consensus among many thoughtful scientists.
If we're going to consider natural selection to be so strong an evolutionary mechanism, then we have to consider mutation and genetic drift to have the potential to be just as strong--depending on the snapshot in time/space/organism and there have been many of these snapshots, to put it mildly. Further, to ignore the potential for gene flow to spread and to create new combinations of genes with potential to create new phenotypes that fail or flourish (i.e. under natural selection and/or genetic drift) in different circumstances is to lack an imagination--and a guttery one at that.
And these assumptions about selection's great strength relative to other mechanisms of evolution illustrate our biases and fashions, as well as the limits of our observations, our methods, and Science. These major issues in evolutionary biology are real and they're certainly not respected by statements like " We stopped natural selection." For a public that often mistakenly equates evolution with natural selection, it’s just reinforcement. And, no, evolutionary understanding isn’t just about being academically correct; many of us strongly believe that how we understand or misunderstand evolution affects how we think about social inequality, race, other organisms, caring for the environment, etc and, therefore, how we behave regarding those issues.
I’ve written a few posts that speak to the importance of evolutionary understanding, like:
- Evolution is the only natural explanation. And it’s all we need.
- The F-words of Evolution
- Another F-word of Evolution
- Evolution’s got a P.R. problem
- Taking our (lovely lady) lumps
- Luck of the draw
- Please make us teach creationism
And, granted, Attenborough admits he’s privileged so this isn’t a comment aimed at him, but. … Isn’t it just a bit soon to be including the entire human species in such a healthy, well-nourished, low youth mortality, long life expectancy state of nature that has “stopped natural selection” on ourselves? I think we have a long way to go before such a definition of humanity can be granted to all of us. And even if or when we, as a whole, achieve such a comfy state, we still won’t be able to say that natural selection has stopped for the reasons I discussed above, and for others that I didn't.
What’s more, if we did achieve the kind of wizardrous skills that deem us impervious to natural selection, it couldn’t have occurred until recently. So it’s probably a bit premature, based on our limited observation, to conclude that’s where our species is.
I'm right there with Attenborough in sharing his astonishment at how we affect our own evolution, and that of other species, in ways that might not have unfolded if our cognition and culture had not evolved first. In fact, I think it's so fascinating that I'm writing a book about it right now. But if we claim that human cognition and culture have ended natural selection, we're denying our place in a universe that we cannot completely control. We are not immune to effects of the world around us, no matter how masterful we are at manipulating it. Climate, weather, geological processes, disasters, infectious diseases, parasites, symbionts (we're full of 'em and covered in 'em!)… these are just some of the things that affect our evolution through natural selection (and other means) as well as all the evolution of the species we depend on for food and all the species besides us that our food depends on. Evolution that's occurring just as constantly in everything around us and on us and inside us as it is in our own genomes will directly and indirectly affect our future evolution. There are few blanket rules in biology but here’s two: Evolution of an organism is always happening and always will. Evolution in one organism is affected by evolution in another.
What’s more, if we did achieve the kind of wizardrous skills that deem us impervious to natural selection, it couldn’t have occurred until recently. So it’s probably a bit premature, based on our limited observation, to conclude that’s where our species is.
I'm right there with Attenborough in sharing his astonishment at how we affect our own evolution, and that of other species, in ways that might not have unfolded if our cognition and culture had not evolved first. In fact, I think it's so fascinating that I'm writing a book about it right now. But if we claim that human cognition and culture have ended natural selection, we're denying our place in a universe that we cannot completely control. We are not immune to effects of the world around us, no matter how masterful we are at manipulating it. Climate, weather, geological processes, disasters, infectious diseases, parasites, symbionts (we're full of 'em and covered in 'em!)… these are just some of the things that affect our evolution through natural selection (and other means) as well as all the evolution of the species we depend on for food and all the species besides us that our food depends on. Evolution that's occurring just as constantly in everything around us and on us and inside us as it is in our own genomes will directly and indirectly affect our future evolution. There are few blanket rules in biology but here’s two: Evolution of an organism is always happening and always will. Evolution in one organism is affected by evolution in another.
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| Conquering a sperm whale. |
So, sure! I can speculate about our future just like anyone else. Here’s how natural selection will affect human evolution at some point in the future. It's not so much a tale of our interconnectedness with other species as a tale of our interconnectedness with the planet. Everyone knows that heat is bad for sperm production. It’s possible that the earth will eventually get so hot (thanks to our cognition and culture???) that sperm production ceases in many men living in the hottest parts of Earth and that it only persists in the men who live in cooler regions and in the men with mutations for overcoming the obstacle. As a result, we’ll lose lineages evolving in the tropics and maybe all lineages. And if the warming occurs quickly and uniformly, and if there are no mutants already alive who can make sperm in the heat, global warming will certainly cause human extinction. There. See how easy it is to speculate about future human evolution? You can’t prove me wrong.
And, like our speculation about the evolutionary future, many of our hypotheses for the evolutionary past are nearly as unpwnable as natural selection and evolution are.
*I don't know him, but like many of you, I have admiration and maybe even a little (or a lot of) affection for David Attenborough. So this isn't about reacting to a popularizer of science, as a person. These are just my thoughts about something he said about how evolution works. This isn't about Attenborough, it's about us.
Thanks to the folks at io9 for reposting this on their site! http://io9.com/we-are-not-the-boss-of-natural-selection-it-is-unpwnab-1325126849
And, like our speculation about the evolutionary future, many of our hypotheses for the evolutionary past are nearly as unpwnable as natural selection and evolution are.
***
Thanks to Barbara J. King for sparking me to think about these things. Her reflection, including some of my input, is up on her blog at NPR.
Thanks to the folks at io9 for reposting this on their site! http://io9.com/we-are-not-the-boss-of-natural-selection-it-is-unpwnab-1325126849
This is a great, cogent, and clear statement and reply to the kind of simplicity so often found on television by the 'experts'.
ReplyDeleteHumans have always controlled our evolution by social life, tool use, and so on, and we still affect it, but of course, as you say, in our own way.
Evolution is not all about survival, but at least as much about reproduction, and indeed there is more 'room' for selection by differential fertility these days than by differential mortality (that's been known for a very long time--it was a major aspect of my dissertation decades ago,and I didn't invent the idea). There is no reason to assume that differential fertility isn't still a substantial factor in our evolution.
A huge population usually evolves more slowly than small local ones, so we may have slowed down...until the next epidemic?
The media need simple stories. Dumbing down sells, and even the public 'experts' seem to get brain-numbed by doing this.
Maybe what the media needs are people like you, Holly, who can tell a more accurate story and still make it readable, understandable, and even enjoyable!
It was truth, not flattery.
ReplyDeleteActually, as some of your images suggested, if we were living in the past, we would probably have similar ideas: any 'present' will seem static, adaptive, and perfect.
Homo erectus would look at themselves and say the past had led them to rise to their wonderful state.
Chimps might feel proud of their accomplishments, too. And think of how fish, so remarkably skilled, might feel!
I'm right there with you. I was thinking all afternoon yesterday how to prove that dog vomit slime mold hadn't stopped natural selection on itself!!
ReplyDeleteP.S. whoever named it that is my hero
ReplyDeleteStrangely, the comment struck me more as a devil's advocate kind of statement: "If Natural Selection is the way organisms evolve, and the vast majority of our offspring are living to breed, then those competitive life-or-death means with which evolution selects traits are void." Simplistic, yes, but it strikes a note that Darwinism, as Darwin envisioned it, is not the same as "evolution" we know today. I have a hard time believing that EVERY maintained trait or groups of traits give inevitable advantage. How could that be? We as humans love to interpret every single trait in some beneficial sense. We've all seen it: some psychologist trying to explain why such-and-such detrimental behavior was somehow useful in more primitive situations, etc. But sometimes, I think things just happen because they happen or they are simply more probable. Otherwise, this evolution thing is far too eerily reminiscent of a clock maker determining each minute detail.
ReplyDeleteI'd say first that even 95% infant survival leaves some room for selection. Second, although slow, chance (genetic drift) will still be operating. This would apply to your comment about 'every' maintained trait: indeed, because most traits are polygenic, the trait could be maintained but there would be evolution in its underlying genetic basis.
DeleteYour idea about how we want to find a value-basis for every trait is nearly the same as a religious determinism, because it assumes selection is as all-seeing as a God would be, which is just manifestly false....as your clock maker reference indicates.
This just happen is another way to say genetic drift.
I would also say that we want to be able to 'explain' everything and that verges on saying that everything must have some reason, purpose, or meaning.
To reply to cuppa: I'm not sure I got my point across well if what you commented is a reaction to my post. When I say that nearly everything is experiencing selection that's coming from a p.o.v. that it's nearly impossible to know otherwise.
Delete"If we were living in the past, we would probably have similar ideas: any 'present' will seem static, adaptive, and perfect."
ReplyDeleteThat is an important concept that I fail to explain to most people including scientists. Someone living during the discovery of printing press (or sword or steam engine) was as fascinated and overwhelmed with new technology as we are today. So, to think of ourselves as superior or more creative than people inhabiting the world in the past is preposterous.
Then the question arises to Attenborough's remark - did human evolution stop in 1st century, 14th century, 19th century, or only today?
The problem now as ever is the usual glacial slowness of evolution. Actually, Lamarck was the first major figure to recognize this and try to explain how it could ultimately yield major change.
ReplyDeleteFor many reasons, scientists can be as blind to the obvious as anybody else!
I wonder if Attenborough was thinking of that paper in Human Biology that analyzed birthweight and survival in Italy and found a near absence of stabilizing and directional selection? But I also recall reading that the variance in birthweight increases (something that selection can act on) when infants are born to older mothers (something that is a relatively modern phenomenon). So there will always be variance birthweight due to a variety of factors such as maternal age, etc., no matter how much we technologically try to shape how much of that variance is available to selection.
ReplyDeleteBut you also hint at an important point: how much of differential reproductive success can we actually attribute to natural selection versus "random reproduction." There are a few recent demographic papers that attempt to develop null models of random reproduction, such that one can compare the expectation of random reproduction with actual patterns of reproduction in order to help us determine the role of natural selection versus other factors.
And here's some pointless trivia: Many Molly Hatchet album covers were designed by Frank Frazetta. Frank's cousin is Tom Frazzetta, who wrote one of the first books on Evo-Devo, back in 1975: Complex Adaptations in Evolving Populations. This book was among the first to merge population dynamics, development, and adaptation and it talked about things like "integration" and "quasi-independence" long before their current popularity.
Thanks so much for this comment Rich
Deletehttp://judgestarling.tumblr.com/post/61230958839/eugenics-the-right-genetics-and-the-right-political
ReplyDeleteI'm particularly fascinated by the evolution of innate human psychological traits, such as violence, intelligence, lust, cunning, religiosity and so on.
ReplyDeleteThe direction in which these may evolve will be determined, presumably, by any future changes in our social environment.
I would argue that the genetic basis for these traits are not human-specific. Instead, I think our ability for symbolic language and thinking--for culture--leads to expression of these of our mental abilities in a context-dependent way.
DeleteYes, I agree. With the exception of religiosity, all these psychological traits are applicable to many non-human species as well as to humans. In that sense, they are surely genetic rather than cultural in origin.
DeleteThe degree to which they are 'encouraged' or 'discouraged' will be determined by the social environment. Over a sufficiently long period of time, they will be subjected to the forces of natural selection.
Presumably, it is entirely possible for chimpanzees or dolphins to evolve much greater degrees of intelligence and self-awareness and, eventually, even a degree of religiosity. This would create problems for human religious institutions (whatever they may look like in 100,000 years' time!).
For a more in depth discussion on the nature of religiosity, see the comments section of http://www.richarddawkins.net/books/5377
Bruno Ditri
I'll happily talk about the genetics of "religiosity" when there's a gene identified ... and one that's not also explained just as well by its involvement in language and memory (and imagination if you think of it as memories of the future). Until then, I think it's premature, among other things, to talk about religious beliefs as if they require a special evolutionary, let alone genetic, explanation.
DeleteHello Holly.
DeleteThank you for your reply.
The inability of current technology to identify specific genes for religiosity does not, of course, negate the existence of them!
Genes for love, anger or lust cannot yet be identified, but most scientists would agree that these human psychological traits are innate and genetic - rather than cultural - in origin.
This logic is based upon the universality of these traits throughout all human societies. Religiosity has a similar degree of universality. Of course, individuals vary enormously in the degree to which they exhibit love, anger, lust and religiosity. However, it would be absurd for an individual with little or no anger to claim that anger is not an innate genetic trait in humans, or that it is cultural in origin.
Every single thing about humans involves genes.
DeleteEvery single thing about humans involves genes.
DeleteOMG. Gene duplication! That. Just. Happened.
Deletehow can natural selection explain a new biologic system like motion system? even we as intellegent designer can make a system like this in a small steps. so how can evolution can do this?
ReplyDeletei read a paper thatsaid that even for one protein we need 10*60 mutations. is a lot!:
http://www.ncbi.nlm.nih.gov/pubmed/15321723
It is always possible that there are fundamental aspects of life that have not yet been discovered. We can never be sure--this science, after all, and we have to find out about Nature (there are no 'sacred' texts that explain it perfectly for us).
DeleteBut based on what we know, the issue (I think) is largely in numbers we just can't really understand. Life (and its proteins) have been evolving for well over 3 billion years. The number of organisms is millions or more for each species, at any given time, and species exist for millions of years.
Not all possible mutations have arisen, perhaps, but there is usually not just one mutation that could enable something new to happen. There are millions of them. Chance and natural selection lead whatever works to proliferate. Of all the things that might have happened, which are essentially countless, what we see today (and what, as animals we ourselves are), is the array of those molecular mechanisms that passed through those screens.
That is the best theoretical understanding we have today. It has shown very high predictive power. That's why we accept evolutionary theory as generally true, even if we know that there are many aspects we do not yet understand.
ok. lets check this. for a one small protein of 100 amino acid there is 20^100 possible sequences. how many of them are functional? like the number of the atom in the universe?(somthing like 10^70) is nothing compare to the entire possiblle combinations. so again- its a huge problem to the evolution. even for 10^30 mutations in a complex animal like mammals we need bilions of year. not milions.and natural selection doesnt help because there is no function until the all 100 amino acid in the place.
DeleteThis kind of argument has been raised by a stream of other creationists, and has been answered just as many times by science with cogent materialistic as opposed to mystic reasoning. So no more of it on this blog, please. There are plenty of places to express your view.
DeleteVery interesting piece. I'm a great admirer of Attenborough, but I disagree with him on this. Steve Jones also made the same point a few years ago, though I have not heard him argue it more recently.
ReplyDeleteI do think it is naive to assume that, just because we have effectively conquered infant mortality (although not our low fecundity) in the developed world, that this rules out selection in other aspects or even for the rest of the world. It's interesting to think that, as our mobility increases and our effective population size increases, that selection is likely to become a more powerful force than drift.
Ed,
DeleteI think it's all much more subtle than this, and involves subjective ideas about what 'evolution' is, ideas that are inherently hyper-selectionistic. Every new person inherits about 150 new mutations in 'single-copy' DNA and countless more in repeat regions of various types. These and all existing variants (about 1 per 100 base pairs even in a small sample of people) change frequency every generation. That's evolution, and if anything there's more total genomic flux than every before (since our population is greater).
So maybe the Attenborough's (and Steve Jones's) of the world, who are glib varnishers of what evolution is about, are just referring to complex traits that are affected by natural selection. But, as you note, there's no reason at all to say those won't change, even if (unless due to horrific trauma) will take longer because our population is so huge.
And 5% infant mortality is not trivial if prenatal traits or traits related to fertility are affected by genetic variation. And if traits in the living affect their ability to find mates or reproduce, neither the infant mortality nor the long life expectancy figures that are tossed so facilely around, have anything relevance to how much evolution could occur in such traits.
Holly, I have a serious question.
ReplyDeleteI don’t think Attenborough was really saying that natural selection had stopped working so much as he meant that contemporary humans were outwitting it to the extent that we could say that humans were no longer evolving. That is, there will still be genetic change like mutation and genetic drift (as you say). But as a species as a whole, we’re not under the kind of selection pressure that we were in past centuries and past millennia.
I guess one of the most recent adaptive changes among humans is that natural selection made northern communities lighter skinned to help with vitamin D production from sunlight, but made equatorial communities darker skinned to help protect from skin cancer. But given all the migration that happened in modernity – that is, roughly, the last 500 years – there are now lots of light skinned people in equatorial places and dark skinned people in northern places. Natural selection is unlikely to weed these people out because of increased clothing, indoor jobs, sunscreen, and cancer fighting technology (for the light skinned folks) and vitamin D supplements and vitamin D rich foods in supermarkets (for the dark skinned folks). In that sense, it’s not that natural selection has stopped operating as that human culture has generally outwitted the selection pressure that otherwise would have prevented the people whose ancestors have migrated from passing on their genetic heritage to future generations.
I’m not a scientist and I have only a lay understanding of evolution. I see your point about the danger of thinking we now control the process – as you point out, catastrophic events like global warming could quickly cause selection pressure to pick up. But isn’t the key here natural selection?
In the Evolution textbook by Nicholas H. Barton, et. al. (Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press, 2007), they write that natural selection is “the most important evolutionary process” because it “is the only process that leads to adaptation” (458, 457). They continue: “Although many processes shape evolution, natural selection is special because it alone creates complex, functioning organisms. All other processes tend to degrade what has been built up by natural selection, simply because these processes act at random with respect to function. Mutation makes random changes in DNA sequence that, if they have any effect at all, tend to disrupt function. Migration introduces genes from elsewhere, which tend not to be adapted to their new environment. Similarly, recombination and random drift will, on average, disrupt genotype frequencies that have been built up by selection so as to increase fitness” (463).
I’m not sure what exactly Attenborough meant to say, but isn’t it correct to understand that the most important evolutionary process of natural selection is currently and widely being thwarted by human culture and technology?
I addressed many if not most of your points and answered your questions already in my essay.
DeleteAlso, that view of evolution you quote from that book is not shared by me or all.
DeleteI encourage everyone to go out there and try to falsify their natural selection and adaptation stories/hypotheses or those of their friends and then re-join this conversation and tell us how that panned out.
DeleteSorry if I seem grumpy but given the exposure this essay's received on io9, by now I'm feeling pretty awkward about all the talk of Attenborough (I never wanted to make this personal or about mind-reading) and I'm also pretty tired of arguing over points I've already made (I guess poorly) in my essay and the links I've provided in it. There are a couple paragraphs in that essay about how one could describe natural selection being slower or weaker in us, especially now, than in the past so... sure! The point is to say it stopped is wrong and has negative ramifications for how we continue to misunderstand evolutionary processes and assume evolutionary knowledge. That's what I was trying to get across up there. I'll keep trying to do better at it with writings to come.
DeleteI've stayed mostly out of this long set of exchanges, because this was Holly's post and she wrote it very well and (I think) clearly and correctly.
DeleteToo many people, including those in various life sciences not to mention the media, have very confused ideas about what 'evolution' means--as a word or concept to them, and as its scientific reality.
Not only is there the tendency to view the discussions in terms of Disneyfied concepts of evolution, conceptually transforming thousands of generations' worth of creepingly slow change to a speeded-up thrilling melodrama. It makes could imagery, good TV, and it's easy to think that way.
Even if it were true that we're evolving very slowly--and that is debatable and depends on what one means by 'evolving' and 'slowly'--we have no way to know what might come along in the future.
One might say that future evolution, say, to change things so we could see better in the dark or do calculus faster, or develop more functionally powerful big toes, would take forever so even were that to happen we're not really evolving the way we used to and the way other species do.
But such changes usually take thousands of generations, and are basically imperceptible at any given time. It is this slowness that perhaps more than anything now, or were we to observe it in the past, that makes adaptive evolution seem so perpelxing--easy to invoke, hard to prove in specific individual cases. Easy to demonstrate in terms of patterns of genomic variation, but then rather abstract in terms of what the genes are doing and why they evolved.
Ken, you're always welcome to jump in any time. You know how bad I am at comment threads... so do I. Which is partly why I usually don't elaborate in them. The other reason is that usually I've said all I have to say in my post, for the time being at least.
DeleteYes, and maybe it's time to close this discussion. In any case, grasping these aspects of evolution is harder than catching an oiled eel, and seems to have been elusive for the 150 years since Darwin.
DeleteAt least one final thought for people who are reading this far before we do leave it be...
DeleteFor us to have a present to bias and even trick us into seeing perfection everywhere (especially in ourselves, but also in long nectar-licking bat tongues, e.g.) requires that past conditions were just as adaptive, just as perfect at any given snapshot of observation! And there were innumerable and still are. Now, with that in mind, let's try to make sense of natural selection as more than the fairy tale (grim or whim) that we've been fed and instead as something much more complex, nuanced, and maybe sometimes extreme, but also often subtle and certainly not necessarily "the" "most" "important" process in evolution as if it can stand alone and all-mighty without others (which it requires like mutation) that lend themselves to non-selective evolutionary processes too.
I’m sorry I framed my questions in terms of Attenborough whom I really don’t know much about. And anyway, like you say, there’s no point in trying to guess what was on his mind.
DeleteI didn’t realize that natural selection was no longer seen by all as the cornerstone of evolution. I’m not a scientist at all and have only read some books, but am keenly interested.
My questions were honest because I had been having a similar conversation about whether evolution was still occurring when Attenborough made his comment and you wrote your essay. I realize with the older example of lactose tolerance and the newer one of amylase that these are examples of recent evolution. But both these examples are thousands of years old at least, so they can’t really function as examples of evolution still occurring today, within the modernity that has taken shape in the last 500 years or so.
I take Ken’s point that evolution occurs very slowly and would be imperceptible to the present. I don’t mean to be disputatious – like I said, I’m interested but untutored in the science of evolution. But it’s difficult for me to imagine a scenario in which the ability to do calculus faster or to see in the dark better gives a survival and reproductive advantage to those who have such genes – at least under current modern conditions. Of course, a global catastrophe could change that – global warming leading to increased cloud cover and global darkness, wherein the ability to see in the dark does confer an advantage? But under those conditions (of no sunlight) we all would have much bigger problems. (As Cormac McCarthy’s The Road suggests.)
As you can see from my counter-story, I am stuck in a rut in terms of thinking that natural selection is the key. Can you recommend a book or books that, contra to the evolution textbook I mentioned, puts natural selection in its place, as it were, among the other evolutionary processes?
My and Anne's book The Mermaid's Tale should still be in print. We discuss these things,of course, since we care a lot about them. I would say books by Richard Lewontin (e.g., It Ain't Necessarily So, or The Triple Helix) do that. Michael Lynch has a paper in PNAS about 2007 or a book of about that time (The Origins of Genome Architecture), or Masatosh Nei's new book (Mutation-driven Evolution). Of these, Nei and Lynch are more technical.
DeleteThere are countless other places for similar views, that are not just propaganda for the view. Articles and books at all levels. The point is not that selection doesn't occur, nor that it's unimportant, but that there is (we think) too widespread a view of its precision and ubiquity, not just as something always possible but something always the major explanation for evolutionary change.
Apologies to Holly, I know this thread is closed but I've really enjoyed reading it. I'm reading Lynch's book at the moment - I should have probably read it earlier given my line of work - but its a really nice synthesis. I will look forward to getting Nei's book from the library.
DeleteIt's difficult to avoid thinking along adaptationist lines sometimes - I see students do it, and I do it as well before mentally pulling myself out from an adaptationist crevice. It also relates to the burden of evidence required before we can say that natural selection has operated. I think the lactase story has enough evidence now, but the amylase story is not quite there yet (although I think its probably right...)
I've also strayed somewhat off-topic...
If we really want to understand nature, rather than just make up stories or claim that we do, selection and adaptation often remain the most elusive of topics, I think. It is too easy to think of simple competition with winners and losers, than of more subtle--if demonstrably more obvious--nuances of life.
DeleteNei's book will be less helpful, probably, though interesting and worth reading just to see such a prominent thinker ruminate about things. Lynch raises some very interesting, almost mystical questions: how can something that is 'deleterious' rise to fixation? We can of course write statistical/mathematical models, but the meaning is rather weird!