By Massimo Pigliucci
You’ve heard the claims: men are inclined to cheat on women because natural selection favors multiple offspring from multiple mates, especially if you don’t have to pay child support. Even rape has been suggested to be the result of natural selection in favor of “secondary mating strategies” when the primary ones fail. And of course we all know that men prefer the same waist-to-hip ratio across times and cultures because it is the one that is most highly correlated with female fertility, no?
Welcome to evolutionary psychology, a discipline curiously situated at the interface between evolutionary science and pop psychology, where both wild and reasonable claims seem to clash against the wall of an incredible scarcity of pertinent data. It will be the topic of an upcoming Rationally Speaking podcast.
To be fair, most evolutionary psychologists are careful to separate “is” from “ought” — in pure philosophical fashion, one might add — and clearly state that just because rape is natural it doesn’t mean that it is moral. Still, the evolutionary study of human behavior is controversial for a variety of reasons, not just because feminists take exception to the way women are thought of by researchers in the field.
Take for instance, the waist-to-hip ratio hypothesis. The idea was first proposed by Devendra Singh in 1993 and a Google Scholar search easily shows how frequently the claim has been repeated and re-investigated. But the idea that a particular waist-to-hip ratio is a universal indicator of sexual preference by human males across cultures and times is simply false, as several studies have clearly shown (for instance, here and here).
The issue that we will explore in the podcast is not whether it makes sense to apply evolutionary principles to the study of human behavior. Of course it does, human beings are no exception to evolution. But the devil is in the details, and the details deal with the complexities and nuances of how exactly evolutionary biologists test adaptive hypotheses, as well as with the nature of historical science itself.
One frequent claim against EvPsic is that you cannot prove the argument that some trait evolved in our evolutionary past, because there is no fossil evidence of that. However, this particular objection could also be raised against a multitude of other evolutionary claims, such as the link of fairer skin and lactose tolerance with living at high latitudes where sunlight is weaker, or the claim that cheetahs and gazelles have co-evolved in their ability (and velocity) to hunt and escape the hunters respectively: nobody has witnessed the slow increase in cheetahs' speed and the corresponding increase in gazelles' spped: we only have the situation today, with both animals having a definite set of abilities to hunt and escape hunters. But in all cases there are valid arguments to derive an evolutionary explanation.
ReplyDeleteMay be, of course, that some supposedly transcultural trait (like the hip-waist ratio) is not actually universal. That would be one hypothesis to discard, a common occurrence in science. But suppose you actually find some transcultural trait, that you can link to some evolutionary mechanism of natural selection enhancing reproductive fitness (it does not need to be a controversial trait like anything related to gender roles; just think of more mundane things like the ability to recognize faces or to tell friend from foe from afar, or the mental abilites needed to make some specific kind of tool.
I am far from being a "believer" in EvPsic (or for that matter a "believer" in anything). I just think that science is not a collection of propositions about reality, but a method or approach to the growth of knowledge. If scientists working with EvPsic theory are able to predict novel facts, and get these predictions corroborated by facts, so --as Darwin said-- we'd have at least a theory on which to work.
As a general advice, I would recommend not starting the analysis with controversial subjects (like gender or religion). Start with more prosaic things like eating, feeling physical disgust, visual perception, counting, making simple additions and subtractions, and so on. Research on the behaviour of very young infants (only weeks or a few months old), for example, show they have certain unlearned mathematical abilities, and this seems to be truly transcultural. The same with the ability to recognize that others have a mind, and to figure out what they know or do not know as compared what the subject does know, thus enabling the subject to cheat. In humans this is achieved by preschool children, and is also achieved by apes. The said abilities can also be easily explained by natural selection processes (apes have the same abilities, albeit somewhat less developed than we H.Sapiens).
We cannot go on in this subject without a serious attempt at actually taking on board the relevant literature. I recommend Mithen, The prehistory of mind; Barrow et al The Adapted Mind; Geary The Origin of Mind; Pinker, The Blank Slate; Barrett et al, Human Evolutionary Psychology; Humphrey, A History of the Mind, and several others.
Admittedly, this branch of science is still young, and many hypotheses are still unproven, or have been refuted, whilst many other have stood scrutiny rather well.
Allowing sex or religion early in the debate would be misleading, just as introducing religion in a debate on the theory of evolution or on the origin of the universe. Concerns about how the science may clash with our ideas about religion, morality or gender roles may be safely left for later, once we have understood what the science is about and how much we know about this matter.
I'd like to add that 'transcultural' does not mean that a behaviour is universally engaged, regarded as legitimate and morally approved in all cultures. It means it is often observed in all or most cultures, and that the urge or desire to behave in that way is quite common in all or most cultures studied, even if some cultures tend to deligitimize, look askance or punish that behaviour.
ReplyDeleteIf one finds, for instance, that in all cultures it is observed that swallowing your own saliva or nasal mucus is acceptable and routinely done without complaint as long as the stuff is still in your mouth or nose, but causes disgust and rejection when it has already left your mouth or nose, that may be a good candidate for a transcultural trait (for instance, spit some of your saliva or nose content in a previously sterilized container, then try to drink it in the case of saliva, or to send it back down your airways in the case of the content of your nose). You would not do it easily (after early infancy), whether you're a British aristocrat, a Chinese, a Tasmanian native, a Brahmin or untouchable from India, a snail-eating Frenchman (or woman), or an ant-eating native from an Amazonian tribe. You would put an ugly face and reject the stuff.
This kind of thing, which has been empirically in multitude of observations or experiments all over the world, is the primary stuff of evolutionary psychology. Then other matters are built on those primary discoveries.
There are also some other traits that could be traced to natural selection in more recent times (not in our distant hunter-gatherer phase), such as some specific (high) mental abilities and (high) testosterone and sperm count levels in European (Askenazi)Jews (a controversial subject if there is one more controversial than gender and religion). See Cochran, The 10,000 year explosion, to find out about this and many other recent evolutionary trends in human physical and psychological traits, all evolved after the agricultural revolution in the early Holocene, and thus much later than the usual "common evolutionary environment" discussed in EvPsyc in which traits are primarily supposed to have evolved when we were hunters and gatherers in West Africa during the latest few million years.
Quite an interesting subject, not to be waved away with a few remarks about determinism or suchlike. Philosophy in this matter cannot help but being scientifically informed to proceed further than ideology or after-dinner small talk.
Hector M. said..."Allowing sex or religion early in the debate would be misleading, just as introducing religion in a debate on the theory of evolution or on the origin of the universe. "
ReplyDeleteInvestigating religion empirically isn't remotely equivalent to investigating science theologically. Science isn't the reciprocal of the Spanish Inquisition.
I don't want to grant religious apologists the status of culture war martyrs, but at the risk of throwing fuel on the pyre:
Evolutionary Religious Studies
Evolutionary Religious Studies (ERS): A Beginner’s Guide
Explaining Religion (EXREL)
Institute for the Biocultural Study of Religion
Evolution of Religion Blog
Poor Richard
Poor Richard's Almanack 2010
I think the problem with the field of evo psych is the types of people who are drawn to it. Lazy, attention seeking, insecure. Many seem to have agendas or preconceived notions (often of a 1950s America vintage) they want to support with "science", always with a jumble of inferences and assertions, never with evidence. Or, as in your example, never with evidence that bears scrutiny (remember "athletes wearing red are more likely to win?" I don't know which was stupider--the patently false "observation" or the evo psych "explanation").
ReplyDeleteI keep a casual eye on it, because it's the most ridiculous, bad-news-bears fringe of the life sciences, yet has somehow attained a veneer of unearned credibility in places that should know better, probably due to its immense popular appeal and headline-friendliness. It is light years away from the conceptual or methodological rigor of evolutionary biology or psychology. Or basket weaving.
Great topic :) I am glad you are devoting a podcast to the topic. Regarding wais to hip ration I would like to point out that claims might be more subtle than the original claim proposed by Singh (that died just a few months ago). There are dozen of studies and articles written on the subject and it's important to look at the whole picture. Here is, for instance, a recent study that found the same preference in blind men: http://www.ehbonline.org/article/S1090-5138(09)00109-3/abstract
ReplyDeleteand here is another aricle by Frank Marlow (more recent one that you brought) that shows that actually the WHR is more similar when it's actually measure on real women rather than just at looking at picture, and that there is possibly different ways to measure it.
Let also remember that universality (or lack of) does not prove that a trait is adapative. It is possible that societies respond differently because there are different environments. We could possibly identigy what are the key variable that prompt adaptive responds as there is much plasticity in human behavior. A simple example from are own history: in the 19th century, thicker women were considered more attractive probably because food was scarce and people that were well fed were usually of higher status. Today, thin women are more attractive as it's a good cue for one's health and obeses people are considered unhealthy. The point is that there is always an interaction between environments and adaptive responds.
It's also important in my opinion to distinguish between adaptations and by products. In their famous book on rape, Randy Thornhill and Craig Palmer disagreed whetner rape is an adaptation (as Thornhill thought) or is it a by product, an extreme and perhaps maladaptive behavior that is part of our range of sexual behavior (as Palmer thinks and I agree).
I am not saying that all the research in the field is good, but it's important to remember that the field exist really around 20-25 years, and methods are improving over time. A lot of early research was naive with really understanding the nuances of evolution and the complex interactions with culture. But overall, the field is producing more and more high quality studies that stem from evolutionary basis. As I mentioned in an earlier comment, we can weight the evidence for or against evolutionary explanations based on the available data. Just because we can't "prove" anything doesn't mean that all explanations are equally likely.
Regarding the issue of ev psych in the media, it is important to report the findings in a more balance and less sensational way. Most evolutionary psychologists are very carefull in what they say but the media doesn't reflect this. They also sometimes tend to pick up the more provoactive studies that are heavily criticized among evolutionary psychologists.
I'm under the impression that behavior is tied to biology through the observation of statistically significant trends among groups. Is the the basis of most findings?
ReplyDeleteIn the case of human behavior, I would expect that the complexity of behavioral factors would seriously reduce the likelihood of yielding significant correlations between biology and behavior. What are the effects of behavioral complexity within a species on the statistical significance of observations?
Side Note: I love the juxtaposition of "men are cheaters" and "men are rapists by nature" with "feminists take exception to the way women are thought of." I'm sure it wasn't intentional, but it just sounds so eye-rollingly familiar.
Miko said..."Lazy, attention seeking, insecure ... always with a jumble of inferences and assertions, never with evidence ... the most ridiculous, bad-news-bears fringe of the life sciences ... veneer of unearned credibility ... light years away from the conceptual or methodological rigor of...basket weaving.
ReplyDeleteHmm. Young scientific fields deserve just as much skepticism as anything else, but your attack seems more akin to vandalism than skepticism.
PR
Poor Richard's Almanack 2010
They are psychological neo Darwinists who aren't allowed to believe that heritable traits were at one time learned experiences, and developed as biological strategies long before the Paleolithic age of man. Dawkins came up with the silly idea of memes to get around that natural selection problem, and the evo psychos replaced that with the even sillier idea of domain specified learning mechanisms that spit out thousands of behavioral modules.
ReplyDeletePR,
ReplyDeleteI don't think all ideas (or fields) deserve equal consideration. I'm not skeptical, just dismissive and disgusted by evo psych. It isn't even wrong... it's a parlor game of assumptions and plausibility, and is offensive to scientists who do the hard work of trying to understand either evolution or psychology. It's also not young, it just has a new name and some effective popularizers.
Point me to any biological evidence for evo psych claims that exceeds the evidentiary standards of, say, homeopathy.
The negative reaction people have to evolutionary psychology would go away the moment people realise that descriptive doesn't mean prescriptive. Then the discipline can be judged on its own merits.
ReplyDeleteI would like to also point out that the media and the lay people usually tend to concentrate on a very samll portion of the research in the field. Evolutionary psychologist Gad Saad listed a year ago several research finding that stem from evolutionary psychology hypotheses: http://www.psychologytoday.com/blog/homo-consumericus/200906/evolutionary-psychology-yields-fascinating-and-unexpected-findings
ReplyDeleteAlso, I don't see how the field is different than other psychological sub-fields. If you read research in social psychology for example, you will find less agreements among researchers and same amount of methodological problems as in ev psych. Most of the subjected discussed there are less "sexy" than the one evolutionary psychologists study (or others picking the studies) and thus, don't cause any controversy among non-experts.
Miko said... "[Evo psych is] not young, it just has a new name and some effective popularizers....Point me to any biological evidence for evo psych claims that exceeds the evidentiary standards of, say, homeopathy.
ReplyDeleteImmature may be a better term than young. Psychology of any kind hasn't had high evidentiary standards for long.
However, IMHO there is compelling evidence that 1) genes affect the brain, 2) the brain affects behavior, and 3) behavior affects fitness.
So evo psych has a credible premise and legitimate domain, but it may well have the least amount of hard data to work with of any science.
I'm skeptical, but I don't care for the kind of ad hominid attack that you wage. I like it when science is held to evidentiary account, but I hate it when it is bullied and demonized.
PR
Poor Richard's Almanack 2010
The idea that studying the brain might be helped by considering the process which built it (where relevant and possible) seems pretty reasonable to me.
ReplyDeleteI get the impression that evolutionary psychology (EP) is unfairly maligned. It seems to me that many of its flaws are shared by many other areas of (eg) evolutionary biology but, for example, few people seem to have a problem with the idea that heart evolved to pump blood.
One criticism is that many lay-people spout a great deal of dodgy nonsense about EP, but then that's true of evolutionary biology and I don't think that makes either less valid.
Another is that there seems to be quite a lot of bad (eg poorly evidenced) EP research but then, again, I think this is true in lots of other areas of evolutionary biology and it just means we should ignore the dross and focus on the good stuff.
Another is that quite a lot of things that we might want to know in EP are hard to find evidence for but then this is a common problem in evolutionary biology (such as with organs that don't fossilise) and I don't think it invalidates work that does find relevant evidence.
I suspect that at least some of the hostility comes from the phenomenon described in Steve Pinker's "The Blank Slate" whereby many people are instinctively hostile to the idea that evolution may have left them with anything other than a blank slate for a mind.
I think some sections of some of Pinker's books provide syntheses of reasonable-sounding EP work. For example, I think his section on fear in "How The Mind Works" describes a sensible (if morally questionable) line of research.
All this said, I greatly respect Steve Jones (who clearly knows a great deal about evolution) and I think he has reservations about EP.
The problem is not so much with their observations of behavioral traits, it's with their theories as to how those traits supposedly evolved, which lead to erroneous assumptions as to therapeutic methods, educational methods, preventive measures, loads of cockamamie research presentations, gullible students led down their garden paths, etc., etc.
ReplyDeleteExcerpt from http://www.personalityresearch.org/papers/seltin.html
ReplyDelete"The first aspect of evolutionary psychology refers to its reliance upon natural selection. This specific theory is rarely debated and is so widely accepted that the very domain of biology is reliant upon it. Buss (1991) states that evolutionary psychology also stresses that there is no such thing as a "purely environmental or situational cause of behavior" (p. 461). This aspect refers to hormonal and other physical causes or mechanisms of behavior. It is hypothesized that such mechanisms have evolved because they have behavioral consequences."
Of course the neo-Darwinists here will have no trouble with the idea that traits are randomly selected by assessment of their consequences instead of being shaped though expectations and experiences over eons.
Except the uncanny resemblance that these present day traits are said to have with those acquired (accidentally?) by our ancient ancestors nevertheless belies the notion that experiences were not directly and causally involved. And in such great and specific detail that ancient accidents were really working overtime here humans where concerned.
Thank for doing this Massimo. I wasn't sure whether your disdain for evolutionary psychology was simply reflexive or not. I believe there remains for some a grudge against psychology as simply an interloper amongst the 'legitimate' sciences.
ReplyDeleteMaybe Evolutionary Psychology is unfairly maligned, I don't know it in enough detail to really judge it. What I do know, however, is that much would be gained if more of my fellow biologists were carefully introduced to the is-ought problem, for I have actually encountered arguments on the level of: see, young male and female monkeys or humans show these or those behavioural differences, therefore all policies aimed at gender equality should be scrapped.
ReplyDeleteIt does seem hard not to blame the current ubiquity of the naturalistic fallacy on an unholy alliance of some PR-savvy evolutionary psychologists or socio-biologists and a dimwitted science journalism pouncing on every study finding slight differences between male and female and then running off into lala land with their conclusions.
Miko says evo psych is not young but it IS young (maybe pre natal) in its empirical incarnation.
ReplyDeleteIt seems to me that only with the ability to distinguish genotype variations between members of a species do we have any significant basis for correlating genetic variations and behavior variations within a population.
A huge handicap for evo psych is the lack of pre-modern genetic material.
On the other hand, it seems to me that all human artifacts (we have lots of that junk) are fossils of behavior.
Of course the problem of teasing apart the contributions of nature and nurture is even harder in the evo context than in other areas of psychology. I sure don't envy them.
PR
Poor Richard's Almanack 2010
Alex SL (formerly Mintman) said... "It does seem hard not to blame the current ubiquity of the naturalistic fallacy on an unholy alliance of some PR-savvy evolutionary psychologists or socio-biologists and a dimwitted science journalism..."
ReplyDeleteIs the problem that some psychologists, socio-biologists, etc. are too media savvy or that more aren't?
Isn't it naive to leave anything you really care about too much in the hands of third parties? A business wouldn't depend on journalists to communicate with its customers.
As science becomes more interdisciplinary maybe it should internalize more PR and education capability, too.
PR
Poor Richard's Almanack 2010
I am intrigued by Baron P.'s idea that "heritable traits were at one time learned experiences". May I have please an explanation of how this could possibly happen? Any experience you may have during your lifetime fails to be transmitted into the DNA of your descendants.
ReplyDeleteOf course, if I happen to have some experiences or learn something that led me to survive better than my peers, I may possibly be leaving more descendants, but those descendants would not inherit those experiences. They would only inherit my DNA (along with the DNA of their other parent), and my DNA was just inherited from my parents.
I expected to see many a participant with hands on familiarity with Evpsych literature, but up to know I see little of that.
ReplyDeleteAnd I see much insistence on the emotionally charged examples of the rape instinct or the waist to hip ratio, which are likely to elicit emotional more than rational responses.
The best approach is to stick to simple things. And there are plenty in the corpus of Ev Psych literature.
Of course, many people (especially in what may be called PopEvPsych) have made absurd claims based on the flimsiest pieces of evidence, if any. And those weird claims attract of course the most furious counterattacks. But one does not need to rely on them, does one?
One useful introduction is the book by Mithen, The Prehistory of Mind. Anybody read it? Or any of the other books I mentioned in my initial comment on this thread? Any educated comment, please?
PR said "However, IMHO there is compelling evidence that 1) genes affect the brain, 2) the brain affects behavior, and 3) behavior affects fitness."
ReplyDeleteI'm a behavioral neuroscientist in an evolutionary biology department, so I'm inclined to agree. But these are not the assumptions that frame most evo-psych... they consider specific modern human behavioral and cognitive traits to be the result of selection FOR THOSE TRAITS during and since around the pleistocene. I don't know of any biological evidence for any specific cases of this, and I have never seen biological evidence for this in an evo psych article.
That said, your point is taken about tone. I find evo psych odious because of its frequent is/ought conflation and sloppy rationalizations for social/cultural issues and problems. I feel like its claims, particularly those that get media attention, are the ones that play to our laziest assumptions. I'm sure there are examples of solid reasoning and honest effort within the field, but they are certainly not the ones getting the attention.
I am excited about the fact that there are real advances being made in behavioral genetics in many animals, including humans. Just none of it, as far as I can tell, by evo psych.
Poor Richard:
ReplyDeleteI did not intend to say that being media-savvy is a bad thing, but that some scientists may be guilty of simplifying or sensationalizing their results themselves, even before the science journalists have their chance to mess things up. "We proved scientifically that women should stay at home with the kids" just generates so much more interest than "there are certain chemical differences between the male and female brain, but who know how that plays into the myriad of factors both genetic and cultural influencing our personality".
Hector, I could be wrong, but I interpreted Baron P.'s statement ("heritable traits were at one time learned experiences") to be a reference to the Baldwin effect.
ReplyDeleteIn any case, it seems to me that the Baldwin effect (if it's real) would be a boost to evolutionary psychology (EP), insofar as it provides a mechanism for the heredity of learned behavior - particularly during the EEA (Environment of Evolutionary Adaptedness), when (according to EP) human behavioral instincts developed as "psychological adaptations."
JCM,
ReplyDeleteyour charitable presumption about Baron P.'s meaning may be true, but the ancient Baldwin suggestion (1896) has been out of favor for at least seven decades now. Moreover, for a learned skill to become heritable, according to the said Baldwin effect, it must be later embodied in some selected genes that are then passed to posterity. It is not the learned trait or behaviour that gets transmitted to posterity, but some genes evolved in association with it. At that point, either the genes condition the behaviour without any need of further cultural transmission, or further cultural transmission is still needed. In any case, the hypothetical Baldwin effect would no be relevant: in one case it is a behaviour associated only to genes; in the other, it is a behaviour associated only to culture (not inherited, even if it may be adopted only by those genetically fit for it, just as aspiring to become Miss Universe or a star in the NFL is only for those who have the physical endowment to make that aspiration credible, but the aspiration is entirely cultural.
I guess Baron P. was not thinking along these lines. His thinking was more likely Lamarckian in some vague way, and thus scientifically meaningless. But let's hope he explains his ideas himself.
I was aware that the Baldwin effect has been a subject of controversy over the years, but (at least to my layman's eyes) it still has its advocates.
ReplyDeleteFor example, I recall that anthropologist/neuroscientist Terrence Deacon invoked it in support of his theory of brain-language coevolution (see The Symbolic Species).
And, specifically with respect to EP, a quote in the Wikipedia entry clams that "Baldwin boosters":
'are typically evolutionary psychologists who are searching for scenarios in which a population can get itself by behavioral trial and error onto a "hard to find" part of the fitness landscape in which human brain, language, and mind can rapidly coevolve. They are searching for what Daniel Dennett, himself a Baldwin booster, calls an "evolutionary crane," an instrument to do some heavy lifting fast.'
- from David J. Depew (2003), "Baldwin Boosters, Baldwin Skeptics" in: Weber, Bruce H.; David J. Depew (2003). Evolution and learning: The Baldwin effect reconsidered. Cambridge, Mass.: MIT Press. p. 3-31. ISBN 0262232294.
I'm just saying (and not taking sides).
Yes, if you have to think in labels, I'm referring to something like the Baldwin effect, and how I expect it may well work is best described in the following paper: Social Learning and the Baldwin Effect, David Papineau http://www.kcl.ac.uk/ip/davidpapineau/Staff/Papineau/OnlinePapers/SocLearnBald.htm
ReplyDeleteAn then there's stuff like this to ponder: Was Lamarck Just a Little Bit Right? Lamarckhttp://experiment.iitalia.com/librarysplit2/Was%20Lamarck%20Just%20a%20Little%20Bit%20Right.doc
Hector writes: "Any experience you may have during your lifetime fails to be transmitted into the DNA of your descendants." Any? Wrong, kemosabe. Can you say epigenetics?
Let me add that all life forms develop instincts from trial and error experience, and arguably there were no "first instincts" that preceded biological experience.
ReplyDeleteAnd note also that all social species from microorganisms on up engage in cultural communication. Which is another way they acquire experience.
And they evolve accordingly, whether you like it or not. And conversely, or counterfactually, without experience, nothing evolves.
And all biological evolution is behavioral.
Epigenetics regards mostly differential activation of genes during embrionic development. For grown ups like you and me, no epigenetics in the world can make us bequeath a learned behavioural trait (say, liking Mozart, speaking Chinese as a second language, or rooting for the Leakers) to our descendants without the intervention of cultural transmission.
ReplyDeleteHector M,
ReplyDeleteBehavioral traits are essentially strategic. Those items cited are not examples of heritable behavioral traits, those are examples, as you have somewhat ingenuously confirmed, of how culture gives us the advantage of our experience with communicative strategies.
"Without experience, nothing evolves". More precisely, without biological variation plus differential experience, nothing evolves. But that is not the point. The point is whether a learned or acquired trait can be inherited. It cannot. Period.
ReplyDeleteWhat actually happens is that faced with a given environmental change (say, a changed climate, or a new predator), which one may call a new experience, some organisms in a given species survive and reproduce better than others. If they do so because of some acquired trait (say, because they had learned from their peers a trick to fool that particular predator), their reproductive success will not last: their children (barring cultural transmission) will not have that ability, and would succumb to the new predator. Instead, if they do so because of some genetically inheritable trait (say, longer legs and stronger muscles enabling faster flight), as these traits are (at least partially) inheritable, their children (or at least some of them)will have them too.
This guy Baldwin was writing not only before Watson and Crick: he was writing before the Mendel papers were rediscovered around 1900. Now we know better, even if some use may be found for some aspects of his theory if adequately translated into modern language (I cannot tell about this, but some papers do exist to that effect).
Some genetic traits may be inherited as a by product of cultural transmission, sure. If a band of monkeys learns some trick to get more termites, and this increases their fitness, whatever other genetic traits they may have (say, a characteristic colour in their fur) will enjoy that fitness and expand their share of the population, and their frequency in the gene pool. But I doubt anyone can argue that this is a common occurrence, let alone the general law governing evolution.
If you concede that inheritance of learned strategies occurs at all, then you will have conceded that if it's an efficient way to enhance fitness, it will become common in direct relation to that efficiency. Common in nature doesn't mean frequent, as most all these mechanisms of inheritance work more slowly than we can readily observe, at least in the higher animal kingdom. In the world of bacteria, however, it seems to be a much different story.
ReplyDelete"If you concede that inheritance of learned strategies occurs at all", says Baron P. But that is the crux: does it occur? If a discussion on evolution becomes a discussion about the inheritance of acquired or learned characteristics, then we are in a different debate, one that for all practical purposes has been settled since 1859, and reburied again several times ever since.
ReplyDeleteRegarding behaviours, EvPsych does not say that behaviours as such are inherited. What is inherited is a genetic make up that favours or enables the adoption of certain behaviours. Those individuals genetically more predisposed to fitness-enhancing behaviours may on average survive and reproduce better, and thus those genes would increase their frequency in that population's gene pool.
ReplyDeleteIndividuals possessing those genes will be predisposed to certain behaviours, e.g. by having the necessary mental ability, or the required muscular strength, or the visual acuity required to perceive a threat earlier and thus be able to react in time, or the neurological mechanism provoking a certain response, or whatever it is.
This does not mean that each individual is necessarily committed to behave in that manner. Some will, some will not. Many factors may be at play in individual cases (genetic, epigenetic, developmental, cultural, environmental, biographical, whatever). All this is about population genetics, concerning averages, distributions and frequencies, not individuals.
Except that it was you, Hector, who conceded that monkeys have acquired instinctive strategies for the manual use of tools. And which came first, the opposable thumbs of primates or the strategies that contributed to their evolution? Did primate cultures not contribute to the eventual development of human anatomical advantages?
ReplyDeleteThose such as you who refuse to accept that inheritance of acquired strategies occurs across the biological board are the dinosaurs of evolutionary studies.
I don't have time to get sucked into a debate over the Baldwin effect, but, since I invoked Terrence Deacon earlier, here's a relevant excerpt from The Symbolic Species (pp. 322-3):
ReplyDeleteThis variation on Darwinism is now often called "Baldwinian evolution", though there is nothing non-Darwinian about the process. Baldwin suggested that learning and behavioral flexibility can plan a role in amplifying and biasing natural selection because these abilities enable individuals to modify the context of natural selection that affect their future kin. Behavioral flexibility enables organisms to move into niches that differ from those their ancestors occupied, with the consequence that succeeding generations will face a new set of selection pressures. For example, an ability to utilize resources from colder environments may initially be facilitated by seasonal migratory patterns, but if adaptation to this new niche becomes increasingly important, it will favor the preservation of any traits in subsequent generations that increase tolerance to cold, such as the deposition of subcutaneous fat, the growth of insulating hair, or the ability to hibernate during part of the year. In summary, Baldwin's theory explains how behaviors can affect evolution, but without the necessity of claiming that responses to environmental demands acquired during one's lifetime could be passed directly on to one's offspring (a discredited mechanism for evolutionary change proposed by the early nineteenth-century French naturalist Jean Baptiste Lamarck). Baldwin proposed that by temporarily adjusting behaviors or physiological responses during its lifespan in response to novel conditions, an animal could produce irreversible changes in the adaptive context of future generations. Though no new genetic change is immediately produced in the process, the change in conditions will alter which among the existing or subsequently modified genetic predispositions will be favored in the future.
Hector opines. "Regarding behaviours, EvPsych does not say that behaviours as such are inherited."
ReplyDeleteBut that's exactly what its adherents do say. To quote my earlier remarks, they claim, without any biological evidence, that these are "domain specified learning mechanisms that spit out thousands of behavioral modules."
Not just algorithmic strategies inherited, but specific behaviors that don't require cultural transmission - only cultural fine tuning.
Nobody so far knows how those modules were imprinted so precisely or where they are located in the DNA or RNA, if to be found there at all, but they have faith that the day will come when all will be revealed.
"All this is about population genetics, concerning averages, distributions and frequencies, not individuals."
ReplyDeleteA regurgitation of the central shibboleth of neo-Darwinism.
None of these conceptual measures can exist without the benefits of individual experience, and individuals adjusting to experience.
Baron P., what I said was that, in the hypothetical case that a particular band of primates (within a population of such animals) develops a "cultural" pattern of behaviour (such as using a new kind of tool), that trait cannot be passed to their descendants (except again by learning).
ReplyDeleteNow suppose that pattern of behaviour is culturally transmitted within the band, and not shared with other bands, during several generations. A band is a very small group, at most a few dozen individuals.
If that particular band enhanced their fitness thanks to that cultural pattern, their numbers may expand over those generations. What you are saying is that whatever biological traits are shared by the band, those traits will also increase in frequency within the population, simply because that particular band increases its size.
This includes all their biological traits; these biological traits are unrelated to the behaviour in question: the hypothesis that they developed such a cultural pattern does not imply any biological factor: they are not supposed to differ in biological terms from other similar bands within that population (otherwise, the behaviour in question should be regarded as a behaviour favoured by the band's peculiar genetic make up, evolved previously for some reason).
In such conditions, the band (as far as it expands thanks to their new tool) will cause an increase of all their genes in the population gene pool, but by assumption those genes are on average the same genes possessed by the rest of the population. The fact that they are of a certain shade of brown and that monkeys with that shade of brown increase in numbers will not make any difference at population level, because other bands have also the same shade of brown in their fur. The same goes for any other biological trait they may happen to have.
Your hypothesis seems to be that, once some monkey discovers that new tool (say, by accident), and his success moves other band members to imitate that behaviour and pass it on to their children, there MIGHT be some particular variation WITHIN THAT PARTICULAR BAND that is particularly advantageous for makinf or using that new tool; e.g., some individuals in the band may have better fine motricity, enabling them to use the new tool better. Those particular individuals will gain a fitness edge over other members of the band, and then those biological traits (fine motricity) will prosper.
Yes, it may happen, although the possibility that the two events coincide within a small band with very few adult individuals (i.e. the emergence of the cultural trait and the existence of some genetic variant that enhances the ability to apply the new trait) is rather farfetched.
However, this does not detract from the general argument. In the rare cases in which such a process may have occurred, the actual evolution starts because in the new environment (which now includes the cultural innovation) some biological traits are more advantageous than others, and are therefore selected by natural selection. For this to occur, you would need (a) that the relevant genetic variants exist within the same band; (b) that the cultural trait is retained and culturally transmitted for a long number of generations, enough to allow for the associated biological traits to be selected. If the band, for some reason, abandons the trait (perhaps it was enforced by one alpha male but anandoned by his successor), the possibility of those genetic traits to keep being selected, generation after generation, will be lost.
And we are talking only about a farfetched and convoluted hypothetical case, for the few species where culturally transmitted traits have been detected. This cannot be applied to the vast majority of species on this planet, not even to a majority of primates.
A study of The Effect of Famine on Foetal DNA may establish the plausibility of epigenetic changes being transmissible (at least those that occur in utero). It may be a stretch to apply it to post natal experience, but anyway:
ReplyDelete"The environment can affect the number of 'chemical caps,' which are known as methyl groups – coupled with DNA bases. These caps affect the amount of protein that a gene would produce. On top of that, the caps will persevere for the duration of a person's life and can be passed through to that person's offspring....The study [shows]...how the diet of a mother can affect not only her own offspring's DNA but also the DNA of her grandchildren and so forth for generations.
Also
Stöger R (February 2008). "The thrifty epigenotype: an acquired and heritable predisposition for obesity and diabetes?". Bioessays 30 (2): 156–66. doi:10.1002/bies.20700. PMID 18197594.
And
Wikipedia: "epigenetics is the study of inherited changes in... gene expression caused by mechanisms other than changes in the underlying DNA sequence... These changes may remain through cell divisions for the remainder of the cell's life and may also last for multiple generations. However, there is no change in the underlying DNA sequence of the organism;"
I guess one question is can epigenetic changes persist long enough for their impact on fitness to affect natural selection impacts on the underlying genotype.
At least that's my uneducated and unwashed take on it.
Poor Richard's Almanack 2010
We're finding that the underlying DNA sequence of the organism is not necessarily where evolutionary change needs to take place, and epigenetic change that lasts for generations is not the only mechanism where DNA is not primarily responsible for long term adaptations.
ReplyDeleteCheck out for example this paper The Scientist
Volume 24 | Issue 9 | Page 34
By Anna Marie Pyle
TOUCHING RNA
Excerpt: "We now know from the human genome project and from studies of the human “transcriptome” that the vast majority of our DNA does not encode proteins after
all; rather, it encodes RNA. RNA is far more important in biology than any of us imagined even 5 years ago. Now more than ever, we must understand how RNA folds, how it serves as a scaffold and enzyme, and how it is taken apart by the
engines of the cell. Studies of RNAs like group II introns and remodeling proteins like NS3 have shed a little light on this problem, but there is much more to learn. We are looking forward to the revolution in experimental biology that will
illuminate the dynamic world of RNA gymnastics."
Anna Marie Pyle is the William Edward Gilbert Professor of Molecular Cellular and Developmental Biology and Professor of Chemistry at Yale University.
This and other research points more and more to RNA as the
key to the selective apparatus residing within each individual cell. The apparatus that Weissmann was convinced did not exist.
I am also tired of discussing Baldwinian issues. The discussion may last forever without reaching any conclusion. In my view, events such as those envisaged as examples of Baldwin effects may have occurred in some particular instances, but cannot be used to reshape the theory of evolution.
ReplyDeleteTo say it differently: Events like animals happening to invade another niche are mostly random, and akin to any other random change in the environment. Some groups or individuals may be more apt to deal with the new environment, some may not, and this will happen either when the organisms move into a new environment through their behavioural flexibility (and the availability of a new environment within their reach) or when the environment itself changes at their old location. In any case, differential responses to a new environment may trigger differential changes in fitness and thus natural selection. Nothing to see, move on.
I concur with Baron P. on the increasing evidence on the importance of epigenetics and RNA. But this is a side issue, not relevant to the matter of EvPsych discussed here. The central claim of EvPsych, i.e. that predispositions for certain behaviours evolve by natural selection, may perfectly accomodate that, since it is not necessarily linked to particular ways in which that selection may operate at the molecular level.
ReplyDeleteIn one chapter of Massimo's book "Making Sense of Evolution", and in a shorter section of his more recent book "Nonsense on Stilts", Massimo makes a case that Evolutionary Psychology is less scientific than the study of the evolutionary biology of non-human species. I will agree that this is accurate, but it is an answer to the wrong question: the right question is "Is Evolutionary Psychology less scientific than mainstream psychology?". Most of the objections Massimo raises could be made to ANY approach to studying human psychology.
ReplyDeleteBoth Massimo and Steven Jay Gould also object to Evo Psych's claims to have found "adaptations", and I think these objections are probably correct: Evolutionary Psychologists do claim to have found adaptations, and it is generally not possible to experimentally verify whether the traits they discuss are adaptations or not. If Evo Psych were to restrict itself to discovering species-wide psychological TRAITS, and to always backing those traits up with psychological research independently of the traits' perceived adaptive nature, Evo Psych may be able to contribute a lot to the study of human psychology.
Yes, Hector, curiosity can be overrated. Some might find it disconcerting to think that our own behavior, especially our deepest emotions, were crafted by blind selective forces maximizing genetic transfer into future generations. But to others of us it's comforting to believe it's not our fault.
ReplyDeleteHector, I won't speak for the others, but it is certainly not my intention to "reshape the theory of evolution", and it should be clear from the excerpt above that Deacon treats the Baldwin effect as an established subcategory of Darwinian evolution - albeit, one that assigns a greater-than-usual role to learned animal behavior as an input in the process of natural selection (say, as part of a complex feedback loop). It need not be a generally common or strong force in order to help solve some specific problems in evolutionary history, and Deacon's problem is a specific one indeed (viz. the special case of human symbolic communication).
ReplyDeleteThat's not to suggest that Deacon has necessarily put the Baldwin effect to proper use in this case, or that EvPsych might not generally abuse (or over-use) it. (I will leave that to the experts to decide.) But it seems to me to be very much alive among theorists (at least here in the US), and I can see why EvPsych, in particular, would find it appealing (i.e. as "an instrument to do some heavy lifting fast.").
Baron P said But to others of us it's comforting to believe it's not our fault.
ReplyDeleteIt never was our fault that human nature is what it is, whether we believed that the gods (or God) or blind evolutionary forces were responsible for determining that nature. But that never stopped us from rewarding/punishing individuals, depending on how their actions measure up against a particular set of social sanctions.
jcm, I find it disconcerting to be asked (by some) to believe that it was never life's doing to act as if it's efforts were consequential. Ergo, that it has not evolved by choice.
ReplyDeletejcm writes, re Baldwin effect:
ReplyDelete"I can see why EvPsych, in particular, would find it appealing (i.e. as "an instrument to do some heavy lifting fast.")."
The problem is that they don't find it appealing, because if they did, they would have to abandon the primary aspect of their modular theory that was developed as an alternate explanation for the evolution of human behavior.
By the way, here's a good site to read more about Deacon's thoughts on what I see as the self-directed evolution of our abilities to use abstractions for solving what we were at the same time becoming able to recognize as the more long term problems of survival.
http://www.childrenofthecode.org/interviews/deacon.htm
Baron said:
ReplyDeleteI find it disconcerting to be asked (by some) to believe that it was never life's doing to act as if it's efforts were consequential. Ergo, that it has not evolved by choice.
Well, if that's the case, then (at least in some sense) they're wrong, given that we know that our actions have consequences. To my mind, the important questions are: Do I care about those consequences? and, if so, why?
To be sure, the old-time answers to those question, coming from mythology and religion, are more cosmic and anthropomorphic than the new-fangled ones, coming from science and (secular) philosophy. But, at least for some of us, that does not make the old-time answers more satisfying.
Baron, I've read that Deacon interview before, but I don't recall taking away from it anything about "self-directed evolution." On the other hand, I do recall from elsewhere his defense of teleological language (albeit, with some admission of poetic license) to describe life's unique quality of goal-seeking and -serving (as in: life as an example of the emergence of purpose in nature).
ReplyDeleteThe self-organizing brain, as Deacon describes it, didn't evolve (in my contrarian opinion) by the accident of random mutations producing a weblike series of functional devices that were found to have a purely coincidental fit with the multitude of developing brains' cumulative experiences. Those researches that are able to make what would be an extremely concerted effort will predictably discover this to be the closest to a mathematical impossibility ever.
ReplyDeleteI agree that life is an example of the emergence of purpose in nature. But I'd add the qualification that it's not the first or only example of purposive behavior in the cosmos. Others as I recall have commented on the proposal that the cosmos has acquired its own purposes, the purposive "laws of nature" being a fairly clear example.
ReplyDeleteLife forms of course being the only example we are as yet aware of that can choose to acquire purpose.
My post was responded to on the podcast yesterday, and the response was a major let-down.
ReplyDeleteMy post was abbreviated in the podcast to something like "Don't most of Massimo's criticisms of evo psych also apply to mainstream psych as well?".
Massimo dismissed this, saying that evo psych is all about the historical sequence of man's psychological development. This is not true. I've read about 5 evo psych book, and almost never do they go into any detail about the historical sequence of development. They are psychologists. They are using hunches based on evolutionary theory to go looking for psychological traits. It is evolutionary biologists who are primarily concerned with the history of the development of biological structures.