Political evolution makes the cover of Nature
The piece with which I began this blog on March 4th was about the application of phylogenetic methods derived from Biology to sociocultural topics. That work has now been extended to political evolution and the article by Currie, Greenhill, Gray, Hasegawa and Mace (gated) with a commentary by Jared Diamond made the cover of Nature on October 14(V467, 801-4 & 798-9 gated). (Nature now categorizes its “news & views” i.e. commentaries and its “letters” i.e. research articles by subject, and interestingly, they have categorized this article as “evolution” and Diamond’s commentary on it as “sociology”. So much for disciplinary labels! Perhaps the authors get to choose?)
The topic is again the peopling of island South-East Asia and the Pacific by speakers of Austronesian languages beginning from modern day Taiwan about 3200 BC. The authors mapped forms of political organization (acephalous, simple chiefdom, complex chiefdom or state) onto the tips of a language tree of 84 Austronesian societies and used state of the art phylogenetic methods (described in supplementary materials) to test models of their political evolution. Diamond praises the superiority of the methods used over more traditional narrative accounts (including his own) and usefully summarizes the results as follows:
“First, political evolution increases only in small steps: states and complex chiefdoms don’t form directly from leaderless societies. This conclusion fits historical observations of the formation of complex societies (for instance, the Malagasy, Cherokee and Zulu states), when one unit at the next-lower level succeeded in conquering or incorporating its neighbours. Second, political complexity can decrease as well as increase, in agreement with abundant evidence of the disintegration of states and chiefdoms. Finally, unlike increases of complexity, declines can plunge a society politically several stages backwards. This can happen if a small group breaks off from a large society to form a small new society (as in the colonization of the Chatham Islands from New Zealand), or if political institutions disintegrate (as on Mangareva in Polynesia).”
By contrast, in another recent article on political evolution based on more traditional materials, Abrutyn and Lawrence (gated) argue that gradual quantitative change in sociocultural evolution can reach thresholds where qualitative punctuated change ensues. “Punctuated equilibrium . . . has more empirical support than gradualism in explaining state formation.” In Mesopotamia and Egypt for example states emerged where chiefdoms did not exist.
Obviously we have not yet heard the last word on political evolution.
Smith and Sullivan’s myths
Browsing on the shelves of my university library in an evolution section the other day, I came across Cameron M. Smith and Charles Sullivan’s “The Top 10 Myths about Evolution” published by Prometheus Books in 2007. If I had even googled “evolutionary myths” I would have found it before I wrote my blog posts on the topic! And when I did google it, I found that Michael Le Page had also published “24 myths and misconceptions” about evolution in April 2008 in the new scientist. Since Le Page only lists his without discussing them, I will stick to Smith and Sullivan here. After having belatedly discovered their book, I was curious about what similarities or differences there would be in our takes on these (beyond the fact that they wrote a book chapter about each while I wrote only a paragraph).
They have ten myths and I had twelve. Theirs are a little more popularly-oriented and mine a little more technically-oriented. For example, several of theirs pertain to evolution-creation controversies which do not interest me very much (their #2 evolution is “just a theory”, #8 creationism disproves evolution, and #9 intelligent design is science). Similarly, several of theirs are specifically about human evolution (#4 “the missing link” and #6 “people come from monkeys”) which I ignored. On the other hand, I got into some phenomena (#1 modes of heredity and drift, #4 stability and change, #7 the nature of species, and #9 adaptive phenotypic plasticity) as well as some modern issues such as #6, the relationship between the genetical theory of evolution and development and ecology, which they mostly do not.
We both had some similar myths but used them, at least in part, to make different points. We both had a “randomness” myth (their #5 that “evolution is random” and my #2 that “mutations are random”). They ultimately conclude that mutations are random but selection is not. I thought it important to clarify that the only sense in which mutations are random is Donald Campbell’s sense of blind or non-prescient. We both had a “survival of the fittest” myth – (their #1 and my #5). They use theirs to make the point that all competition is not violent (a point they make again in their #10 that “evolution is immoral” and that I made in my #10 that nature is “red in tooth and claw”). Ultimately however, their #1 and my #5 make the same point, that reproduction matters too and that defining fitness is a complicated matter. We both had a “progress” myth (their #3, my #12). I claimed the concept is scientifically meaningless. They used it in part to discuss the issue of increased complexity which I discussed in my #11 and we agree that there is no necessary tendency for complexity to increase in evolution, albeit it has in some lineages.
We both had a myth that is really ecological rather than evolutionary, but different ones. Theirs was #7, the myth of “nature’s perfect balance”, mine was #8 that “resource depletion and environmental degradation go hand in hand in nature”. There remain a very few significant disagreements. I think they are incorrect in denying that acquired characters can ever be inherited (p. 30), in fact I included that as myth #3, and in claiming that evolution is always gradual (p. 68). However, I found this a very useful book and I recommend it.
What is a Ph.D.?
Matt Might’s guide to what a Ph.D. is has travelled further than most sociology and philosophy of science ever will. So as clever as the illustrations are, forgive me if I quibble a bit with his argument. Might implies that what is taught and learned in elementary, secondary and to some extent in a Bachelor’s program is the core of knowledge. For literacy and numeracy that is undoubtedly correct, but I am not confident that the rest of the curriculum (which, after all, varies greatly by jurisdiction and even by the predilections of individual teachers) always captures the core of available knowledge.
But I object more to his depiction of a Ph.D. and beyond. He pictures a Ph.D. not only as a small bump beyond what is known, but as a narrow one. That is not always the case. In some cases it could be smaller in depth, but broader in width – a thin line of somewhat greater length along the perimeter of the circle – perhaps even line segments at several different places on the perimeter with other bars drawn through the area of the circle connecting them. In short, while it can be, we know that extreme specialization is not always the best route to making an original contribution to knowledge. That is particularly the case when dealing with applied problems where inter, trans or cross-disciplinary research is virtually a necessity.
I did my Ph.D. in Sociology comparing theories of change in biology, psychology and the sociocultural sciences with an interdisciplinary committee including a biologist, a psychologist, several sociologists and a philosopher of science. I have continued on that track throughout my career publishing in a variety of life, social science and science studies journals as well as writing an interdisciplinary monograph. I won’t pretend it is always easy, but it clearly is possible.
The most central theme in my research has been that sociocultural change occurs by processes essentially analogous to those of biological evolution. Alternatively, as some would put it, both are instances of the general class of selection processes (which includes as well as several other processes taking place within individuals such as learning by reinforcement and punishment and the adaptive immune response). So I will use my expertise to make the basic point that what is most adaptive to do depends upon the circumstances and one’s own condition. What is particularly relevant here is that selection can be scale-dependent. In a small scale environment with resources spatio-temporally or otherwise concentrated, it pays to be a fast specialist. But if resources are more spatio-temporally or otherwise dispersed, it pays to be a longer, slower generalist. You can pick more fruit from each tree, or alternatively less from each but from more trees. What is best to do all depends on the existing state of the world and our knowledge of it as well as one’s own predispositions, however acquired.
Beyond the Ph.D., Might depicts one’s view of the world as a black outer ring, implying not only that one appreciates how much ignorance remains, but that one appreciates its breadth. Given the kind of Ph.D. he depicts, that is most unlikely. In that case, the most that one is likely to be able to appreciate, is the narrow black spot immediately beyond one’s own narrow corner.
Twelve evolutionary myths (continued)
7) “Darwin explained the origin of species.” Although Darwin called his book On The Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life few evolutionists believe that he successfully fully explained “the origin of species” specifically. Darwin thought species were like varieties, only more so. While this is the case with asexually reproducing organisms, it is not the case with the sexual. Members of different sexual species do not just tend to look and behave differently and occupy different niches as do varieties, but they are normally incapable of interbreeding with each other. The difference is not unlike that between different dialects of a language and different languages. Most commonly, separation by physical barriers (geographic isolation) often accompanied by genetic drift is ultimately responsible for this “reproductive isolation”, but natural and even sexual selection also often accompanied by genetic drift can produce the same result in some cases. None of this in any way detracts from Darwin’s great achievement in seeing the reality of “descent with modification” among species and that natural selection is a powerful force in nature.
8) “Resource depletion and environmental degradation go hand in hand in nature.” Quite to the contrary, all other things being equal, they should be negatively rather than positively associated. If resources are plentiful, it pays to acquire more and produce more offspring; if they are scarce it pays to instead derive more break-down products from each unit acquired and produce fewer, higher quality offspring which yield more grand-offspring. Acquiring and producing more obviously depletes resources more, but digesting and producing better degrades the environment more. This is because the more concentrated is the “good stuff” extracted/good offspring produced, the more concentrated i.e. toxic will be the “bad stuff” excreted/bad offspring rejected. In some species, higher quality offspring are built up and lower quality ones disposed of routinely as a matter of course, the latter phenomenon is called “obligate brood reduction”. However, the “all other things being equal” qualification is important. Commonly human “developed” societies both deplete and degrade more (e.g. both have more land under cultivation and derive higher yields per hectare) than “developing” ones because they possess the knowledge and resources to do more of both. This illustrates an important point about evolutionary theory. A negative correlation is evidence of a trade-off, but its absence is not necessarily evidence that there is no trade-off. Some individuals can be capable of doing more of both (whatevers), presumably because of superior information.
9) “There is no role for purpose in evolution.” As a minimum, requires qualification. It is true that neither evolution in general nor particular lineages of organisms are moving towards some sought-after or preordained goal. On the other hand, life cycles evolved by natural selection do have an objective, roughly survival and/or reproductive success. Organisms are commonly described as having a “programme”. This programme includes vast hierarchies and networks of genomic sequences controlling the expression of other sequences and even doing so flexibly – not unlike a computer programme replete with “if statements” which is executed flexibly depending upon circumstances. For example, in a patchy environment if resources are plentiful here and now and are expected to be scarce elsewhere/in the future, selection will favour spending on acquiring resources and/or producing offspring. However if resources are scarce here and now and expected to be plentiful elsewhere/in the future/in some other niche, selection will favour investing in future consumption and/or production by moving on (motility), becoming temporarily inactive (maintenance), or innovating phenotypically (phenotypic “mutability”) and/or producing offspring which move, wait, or are mutants. Overall, under uncertainty but with reliable cues, programmes are selected to respond adaptively to circumstances – to maximize “net present value” as economists put it. This phenomenon of naturally selected programmes which permit the flexible pursuit of the goals of survival and/or reproduction in development (and of numerous subgoals in pursuit of those goals) – whether morphological, physiological, or behavioural – is known as “adaptive phenotypic plasticity”. Natural selection explains not just adaptation in a static sense, but purposivism in a dynamic sense.
10) “Evolution reveals nature as being ‘red in tooth and claw’.” Only one-third of the truth. With all the food and space in the world, there will inevitably still be hereditary differences in the ability to acquire resources and turn them into offspring. Although reading Malthus indeed made the penny drop for Darwin, in fact no Malthusian “over production of offspring” is required for natural selection and evolutionary change to take place. It is the case that under scarce resources, competition often takes the form of overt conflict entailing contact and aggression i.e. Tennyson’s “nature red in tooth and claw” – behaviours such as food theft, cannibalism and intra-specific nest parasitism for example. On the other hand, social cooperation as well as social antagonism are possible as well – group hunting in social carnivores for example. Not uncommonly conflict and cooperation are mixed – for example, cooperation within groups and conflict between them. In short, competition can take place in the absence of social interaction of any kind, and social strategies including cooperation as well as conflict are means by which competition sometimes takes place, most obviously under crowding.
11) “Evolution proceeds in the direction of increased complexity.” Not necessarily so. Some animals have evolved eyes, others, living in caves for example, have lost them. The earliest living things we know about (although something else undoubtedly preceded them) were prokaryotic cells – those without a nuclear membrane like the familiar bacteria. To this day, prokaryotic cells remain the most abundant, both in numbers and biomass, on, over and in our planet. Complexity has however increased in some lineages and why and how are interesting questions. One of the most important means by which it has increased has been by over-duplication and divergence of parts serving different functions (whether of genomic sequences, cells and cell groups, body segments or even whole individuals – as in some life cycles which include more than one kind of individual such as a growth form followed by a dispersing sexual form). Another means has been by symbioses (intimate associations among members of different species). Eukaryotic cells (those with nuclear membranes) like ours include what were once independently-living prokaryotic cells for example. However, a general theory of how new levels of more complex developing and evolving individuals emerge (and even in the case of one theory proposing that they actually necessarily do) is currently a matter of much discussion.
12) “Evolution is a theory of progress.” Progress is an inherently evaluative concept. If one values the big and complex, then that is progress; if one values the small and simple, then that is progress. Evolutionary, like any other science, is incapable of answering such questions of value. In the light of that, claims that evolutionary theory justifies capitalism, socialism, or anything else for that matter is too silly to be worth discussing!
Twelve evolutionary myths
1) “Evolution equals mutation plus selection.” This is wrong on both counts. It would be more accurate to say that it equals hereditary innovation, selection and drift. There are forms of heredity other than the genetic including the epigenetic, behavioural, ecological and cultural for example. Even with genetic inheritance, in sexually reproducing species, including most familiar animals and plants, genetic recombination rather than mutation is the source of most hereditary innovations. Natural selection (roughly differences in the ability to survive and/or reproduce based on hereditary differences) is important, but so too is “drift” – the evolutionary term for sampling error, essentially accidents. Just as when tossing a fair coin, in a large number of tosses we expect an equal number of heads and tails but not so in every small group or short sequence of such. In finite populations (and no population is infinite in size), organisms do not always get what they would otherwise. Nature does throw dice.
2) “Mutations are random.” At best ambiguous, depending upon what is meant by random. As used in evolutionary theory, random does not mean uncaused, necessarily unique, or equiprobable. There are many known causes of mutations including ionizing radiation, some chemicals and some viruses for example. Mutations are often a recurrent affair – to the extent that the mutation rate from one version of a gene to another can sometimes balance selection acting against the latter, maintaining an otherwise maladaptive alternative in a population. All possible mutations are not equally probable – “forward” mutations from one version of a gene to another and “backward” ones, their reverse, often occur at different rates. If it does not mean uncaused, necessarily unique, or equiprobable, then what does it mean? As Donald Campbell made clear, the term “random” is ill-chosen. All it means is “blind” or “non-prescient”. On a statistical basis, mutations are not necessarily oriented in an adaptive direction. Most, in fact, are harmful. None of this should be taken to imply that mutation rates cannot be selected and evolve which they can and do in some cases.
3) “Lamarckian inheritance (the inheritance of acquired characteristics) has been proved false.” Not so. If a cell doubles in size and divides once, however the material is distributed among the two offspring cells, 50% of that material was acquired rather than inherited by the parental cell. Lamarckian inheritance then can be half the story. What is false is the theory of Lamarckian evolution – that acquired adaptations, as a result of “use” for example, are preferentially inherited over acquired maladaptations, as a result of “disuse” for example, which, if true, would be miraculous – a skyhook rather than a crane in Daniel Dennett’s memorable terms.
4) “Natural selection causes change in populations.” Not exclusively so. Natural selection can cause change in a population, but it can also maintain stability by selecting against new extremes. There is a story about the views of Charles Darwin and Herbert Spencer on this point. When Darwin read Malthus on over population, the penny dropped and he inferred that the resulting struggle could be the force causing species to change. (He had long believed that they do, in fact, change.) Spencer read Malthus too, but he inferred that the struggle resulting from over population could be the force maintaining the stability of species. When Darwin eventually published his theory, Spencer was chagrined that he had not thought of Darwin’s idea himself. But Spencer had not actually been wrong! Both are possible! Not only can selection cause directional change or maintain stability, but it can also drive wedges in populations splitting them apart as Darwin himself emphasized. After a long hiatus in which it was believed that only geographical isolation could do that, contemporary theory and empirical research now support Darwin’s view.
5) “Evolution equals survival of the fittest.” Only part of the story. Reproduction and not just survival matters. “What matters in evolution is reproduction.”Also only part of the story. In fact, modellers have shown that there is no single definition of “fitness” suitable to all types of populations – with overlapping as well as discrete generations, sexual as well as asexual, with different kinds of life histories, for declining as well as growing populations etc.
6) “Population genetics or the genetical theory of evolution is a complete theory of evolution.” Opinions on this differ as even a cursory review of the macro-evolution and evo-devo literatures reveal, but even confining ourselves to microevolution, I think not. The unification of Mendel’s theory of heredity and Darwin’s theory of evolution which defines evolution as a change in gene frequencies in a population (commonly known as neo-Darwinism in Britain or the synthetic theory of evolution in America and built mainly by Ronald Fisher, J.B.S. Haldane and Sewall Wright in the 1930’s), was a towering intellectual achievement which continues to be refined to this day. However, its elegant simplicity comes at a cost in that while it unifies genetics and evolution, it omits development and ecology. Ideally, a ‘new’ new evolutionary synthesis will be one including not only evolution and heredity, but also development and ecology. I for example have suggested that rather than defining evolutionary change as “a change in gene frequencies in a population”, it be defined as “any change in the inductive control of development (whether morphological, physiological or behavioural) by ecology and/or the construction of ecology by development which results in a change in the frequency of hereditary (including genetical) elements in a population.” As well as including development and ecology, this definition incorporates the cases of both old genes in new environments and new genes in old environments respectively.
Oren Harman’s biography of George Price
Oren Harman’s book about the life of George Price , The Price of Altruism: George Price and the Search for the Origins of Kindness, has been reviewed by W. F. Bynum (gated) in Nature and Frans de Waal in the New York Times and I also enjoyed reading it lately. Harman tells a good story by building a “double helix-like structure” as he calls it for the book – alternating episodes in the ultimately tragic story of Price’s life with those in theorizing about social relationships in evolutionary biology from Darwin to the present – with both set in the context of their times.
Part I of the book largely deals with Price’s life prior to his coming from America to London in 1967 and with the scientific story from Kropotkin and Huxley, to Fisher, Haldane and Wright, to Allee and Emerson, to Wynne-Edwards and George Williams with the development of game theory in the background. Even the moderately well informed are likely to learn some things from this. For example I was surprised to learn that Kropotkin’s Mutual Aid was originally written in the form of five essays responding to one of Huxley’s on “the struggle for existence”. I was also surprised to learn (or had forgotten) that r, the famous coefficient of relatedness in Hamilton’s inclusive fitness equation, was originally derived by Wright, although he did not use it to explain altruism. Part II deals with Price’s life and work in London including the derivation of the famous Price covariance equation until his death in 1975 and with his relations with John Maynard Smith and Bill Hamilton. Harman’s shoehorning the general problem of the evolution of social cooperation and conflict into that of altruism is a bit of a squeeze, but given the undoubtedly important role the latter eventually played in the story of the former, and given Price’s lonely suicide after a period of “living rough” while trying to live up to his new found Christian ideal of selfless altruism – the author’s succumbing to that temptation is very understandable.
We will never know the cause of Price’s tragic suicide. The author tentatively suggests he suffered from the fashionable Asperger’s syndrome (he had a restless and rather unstable personal and employment history). There was an unrequited love. A psychiatrist who saw him not long before his death raised the possibility of schizophrenia (late in life he apparently had fairly frequent communications with God as had his mother). To top if off, his severe hypothyroidism and cessation of medication for it could have resulted not only in depression, but also (albeit rarely) in psychotic hallucinations.
The scientific story is brought pretty well up to date by Harman with the inclusion of Samir Okasha’s contextual analysis or cross-level byproducts approach (essentially multiple regression) to multilevel selection and Benjamin Kerr and Peter Godfrey-Smith’s (gated) more general version of the Price equation which symmetrically permits descendants without ancestors such as migrants for example as well as ancestors without descendants in a population (see also Godfrey-Smith). This appears to be one of those beautiful developments which are classic in the history of science and Harman is surely right that Price would have enjoyed it.
Anyone interested in the history of evolutionary theory or in science studies (the author suggests most of the main protagonists were ideologically motivated) will enjoy this book. Indeed anyone even with little or no prior knowledge but curious about one of the big questions in the history of ideas should as well.
Production, re-production and mentorship in science II
As described previously, Malgrem et. al. (gated) found that mentors with low fecundity (< 3) train protégés that go on to have fecundities 37% higher than expected throughout their careers – what I interpreted as a trade-off of quantity for quality of protégés, with the latter yielding more grand-offspring.
The fecundity of the protégés of these low fecundity mentors appears to increase across their careers (while always remaining higher than expected) while that of high fecundity mentors (> 10) decreases (crossing from above to below expected). In the first third of their careers, the high fecundity mentors go on to have protégés with fecundities 29% higher than expected, while in the last third of their careers, these mentors go on to have protégés with fecundities 31% lower than expected.
Some such shifts might be explained by different initial conditions combined with adaptive phenotypic plasticity. The low fecundity mentors might be so because they are working in a crowded field and so produce high quality protégés. These protégés too then are born in a crowded field and so are initially somewhat low fecundity themselves, but as their career progresses, this combination of low fecundities causes the number of competitors to shrink, and if the protégés are adaptively plastic, they increase the number of their protégés as time goes on. By contrast, high fecundity mentors might be so because they are working in an uncrowded field and so produce many protégés. These protégés too then are born in an uncrowded field and so are initially high fecundity themselves, but as their career progresses, this combination of high fecundities causes the number of competitors to grow, and if the protégés are adaptively plastic, they switch to quality decreasing their numbers of protégés as time goes on.
In any event, for mentors apparently it is not necessarily good to be highly fecund because there is a cost in quality and therefore in grand-offspring. However, given that one is going to be highly fecund, it is better to be so earlier rather than later in one’s career. On the other hand, if one’s goal is the quality of mentorship provided, perhaps later is O.K. There are lessons for graduate students here as well (if the results are generalizable beyond mathematics). You could be well served by not hooking your fate to a star, but if you do hook it to a star, you had better get on board early. On the other hand, if the quality of the mentorship you receive is the goal even at the risk of not getting on board at all, then perhaps later is O.K.
Production, re-production and mentorship in science I
I have been away from this blog for awhile – spring is travel time for many academics and I recently had interesting visits to Paris and Montreal. I came home, among other things, to a couple of issues of Nature. One interesting article by Malmgren et. al. (June 3, gated) on the role of mentorship in science related to a question I had been asked while away .
I had been asked why I talk about offspring “production” and “re-production” rather than the more common replication (for asexuals) or reproduction (for sexuals). The reason I use the term “offspring production” is that reproduction or replication has not taken place until the complete life-cycle has been repeated. Consider for example a semelparous (“big bang”) life cycle in which individuals grow and then produce offspring all at the end of the life cycle. Such an individual grows and produces offspring, but its life cycle has not actually been repeated until those offspring have grown and produced offspring in turn – i.e. until grand-offspring have been born. Until then, it is more logical to say the parents have “produced” offspring rather than saying they have replicated or reproduced.
As for the term “re-production”, it obviously means something like ‘producing again’. Much of the literature in evolutionary ecology uses the term “offspring quality” vaguely without specifying what is meant, e.g. see the discussion in an article by Wilson et. al. in TREE in April on “What is individual quality? (gated). I am saying what I mean (and commonly what others implicitly mean) that by making fewer larger as opposed to more numerous smaller spores, gametes, offspring etc. (and more generally engaging in parental care), parents are assisting their offspring with producing their own offspring in turn. But if I said “reproduce” it would be confused with the conventional meaning i.e. what I mean by produce. So I emphasize the ‘again’ by calling it “re-produce”. Specifically, just as the low-density in size relative to resources favouring consumption can be contrasted with the high-density favouring digestion (deriving more breakdown products from each unit of food consumed), the low-density in numbers favouring offspring production can be contrasted with the high-density favouring re-production (deriving more grand-offspring from each offspring produced).
What has all this to do with mentorship in science? Well using data from some 7,259 mathematicians who graduated between 1900 and 1960, Malmgren et. al. showed not only that success in science (number of publications, USNAS membership) is correlated with mentorship fecundity, but that the same trade-off discussed above between production and re-production obtains there. Mentors with low fecundity (< 3) train protégés that go on to have fecundities 37% higher than expected throughout their careers. “Somewhat counter-intuitive”? Not at all. All other things being equal, as all evolutionists know there is a trade-off between quantity and quality of offspring and, it should be emphasized, high quality offspring go on to produce more grand-offspring. The meaning of their other findings is less obvious however and will be the topic of a later post.
Are humans still evolving genetically?
Some have provided theoretical and empirical reasons for believing not only that human populations continue to evolve genetically, but they are doing so at even higher rates than once was the case. Mark Stoneking has provided an interesting commentary bearing on this in a post on “On the Human” titled “Does culture prevent or drive human evolution?” My attention was drawn to this by the Semiotix Bulletin.
Lamarckian what?
Lamarckian is an adjective which requires a noun after it. The next time you hear or read something is “Lamarckian” ask (at least yourself), “Lamarckian what?” Lamarckian inheritance is no problem. If a cell doubles in size and divides once, no matter how the material is distributed among the two offspring cells, fifty percent of that material was acquired rather than inherited by the parent. So the inheritance of acquired characteristics is ubiquitous. Lamarckian evolution however is a different matter. The preferential inheritance of acquired adaptations over acquired maladaptations, if true, would be a miracle – the kind of thing Daniel Dennett called a skyhook rather than a crane.
The same thing is true socioculturally. An individual may learn something from their own experience, by trial and error for example, and it may be passed on by social learning. But that is no reason to believe that it is therefore likely to spread preferentially socioculturally. A colleague once pointed out in conversation that masturbation and nose-picking may be rewarding in some cases but are hardly likely to become social norms. The fact of the matter is that sociocultural innovations, whether inherited or acquired, are no more likely statistically to be biased in the direction required for them to succeed than are biological innovations. Most fail – whether we are talking about citations to scientific publications, the utilization of patents, the marketing of new products, or the founding of new businesses. Sociocultural evolution is Darwinian rather than Lamarckian.
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