Mark, I started to read this, and make some comments. The main question that occurred to me is why don't the authors consider such things as digging a burrow or migrating to avoid cold as genetically based instincts, as essentially phenotypical expression of genotype. Isn't there such a thing as instinctive animal BEHAVIOR ? If so isn't a form of phenotype ( the paper mentions Dawkins' "extended phenotype")? Finally, why do they treat it as if it is incipient animal culture ? Are they saying that child animals learn , for example, seasonal migration by imitating parents , and that it is not genetically based instinct ? I make a couple of interjections in the excerpted text below, at points in their discussion where these questions occurred to me. >>> [EMAIL PROTECTED] 08/21/00 07:34AM >>> Niche Construction, Biological Evolution and Cultural Change. 1.0 AN EVOLUTIONARY FRAMEWORK FOR THE HUMAN SCIENCES -clip- 1.1 Niche Construction Building on ideas initially developed by Lewontin (1983), we have previously proposed that biological evolution depends not only on natural selection and genetic inheritance, but also on "niche construction" (Odling-Smee, 1988, Odling-Smee, et al., 1996; Laland et al., 1996a). By niche construction we refer to the same processes that Jones et al. (1997) call "ecosystem engineering". Niche construction refers to the activities, choices and metabolic processes of organisms, through which they define, choose, modify and partly create their own niches1. For instance, to varying degrees, organisms choose their own habitats, mates, and resources and construct important components of their local environments such as nests, holes, burrows, paths, webs, dams, and chemical environments. Many organisms also partly destroy their habitats, through stripping them of valuable resources, or building up detritus, processes we refer to as negative niche construction. In addition, organisms may niche construct in ways that counteract natural selection, for example by digging a burrow or migrating to avoid the cold, (((((((((((( CB: Isn't this niche construction instinctive and a phenotype ? ))))))))))) -clip- There are numerous examples of organisms choosing or changing their habitats, or of constructing artefacts, leading to an evolutionary response (Odling-Smee et al., 1996; Laland et al., 1996a). For instance, spiders construct webs which have led to the subsequent evolution of various camouflage, protection and communication behaviours on the web (Edmunds, 1974; Preston-Mafham & Preston-Mafham, 1996). ((((((((((((( CB: Are they saying this web construction or the subsequent camouflage, protection and communication behaviours are instintive or incipiently "cultural" ? Are they passed on through genes or as a "tradition" ? I would assume the former. (((((((((((( Similarly, ants, bees, wasps and termites, construct nests which often themselves become the source of selection for many nest regulatory, maintenance and defence behaviour patterns. Many ant and termite species regulate temperature by plugging nest entrances at night, or in the cold, by adjusting the height or shape of their mounds to optimise the intake of the sun's rays, or by carrying their brood around their nest to the place with the optimal temperature and humidity for the brood's development (Frisch, 1975; Hansell, 1984). The construction of artefacts is equally common among vertebrates. Many mammals (including badgers, gophers, ground squirrels, hedgehogs, marmots, monotrema, moles, mole rats, opossum, prairie dogs, rabbits and rats) construct burrow systems, some with underground passages, interconnected chambers, and multiple entrances (Nowak, 1991). Here too there is evidence that burrow defence, maintenance, and regulation behaviours have evolved in response to selection pressures that were initiated by the construction of the burrow (Nowak, 1991). In all of the above examples there is often strong comparative evidence suggesting that nest building is ancestral to the nest elaboration, defence and regulatory behaviour (Hassell, 1984; Nowak, 1991; Preston-Mafham & Preston-Mafham, 1996). ((((((((((((( CB: They have evolved, but how are they passed on to the next generation ? Genetically or as a "tradition" or "custom" ? ))))))))) Most cases of niche construction, however, do not involve the building of artefacts, but merely the selection or modification of habitats (Odling-Smee, 1988). For instance, many insects choose particular host (((((((((((( CB: They "choose" it ? Is this instinctive choice or "conscious" choice ? ((((((((( Niche constructing organisms may also substantially modify the environment of their offspring, and even more distant descendants. Thus generations of organisms not only inherit genes from their ancestors, but also a legacy of natural selection pressures which have been modified by ancestral niche construction. This legacy of modified selection pressures has previously been labelled an "ecological inheritance" by Odling-Smee (1988). -clip- All organisms constantly interact with their local environments, and they constantly change them by doing so. If, in each generation, populations of organisms only modify their local environment idiosyncratically, or inconsistently, then there will be no modification of natural selection pressures, and hence, no significant evolutionary consequence. If, however, in each generation, each organism repeatedly changes its own environment in the same way, perhaps because each individual inherits the same genes causing it to do so, then the result may be a modification of natural selection. ((((((((((((( CB: Why do they say "perhaps" ? Isn't this definitely so. And isn't this an important point in a paper that compares instinctive behavior and cultural behavior ? I can understand that the authors are pointing to ecological inheritance as structures external to the organisms's bodies and thereby different than the bodily phenotype. But the behaviors that generate the physical structures that persist to a next generation or influence the upbringing of infant animals here are INSTINCTIVE behaviors, not learned as a culture or tradition. clip )))))))))))))))))))) Figure 1: (a) The standard evolutionary perspective: populations of organisms transmit genes from one eneration to the next, under the direction of natural selection. (b) With niche construction: phenotypes modify their local environments (E) through niche construction. Each generation inherits both genes and a legacy of modified selection pressures (ecological inheritance) from ancestral organisms. ))))))))))))))) CB: But the "modified selection pressures" do not modify anew each generation. They are the same for each new generation, because each previous generation "modifies" it in the same way. The only modification would be between the environments of the first generation that aquired the instinctive behavior with a new gene and the one before that didn't have the gene and instinctive behavior. ((((((((((( -clip- We have outlined the principal evolutionary consequences of niche construction elsewhere (Odling-Smee et al., 1996; Laland et al., 1996a). Our goal here is to spell out the repercussions of this perspective for the human social sciences. We maintain that a focus on niche construction has important implications for the relationship between genetic evolution and cultural processes. The replacement of a single role for phenotypes in evolution by a dual role immediately takes away from human culture its claim to a unique status with respect to its capacity to modify natural selection. Humans can and do modify many natural selection pressures in their environments, but the same may be said of many species, and most do so without the help of culture. Moreover, this dual role for phenotypes implies that a complete understanding of the relationship between genes and culture must acknowledge not only genetic and cultural inheritance, but also take account of the legacy of modified selection pressures in environments. To illustrate these points, we need to take a fresh look at how human culture relates to human evolution in the light of niche construction. (((((((((((((((((( CB: Seems to me that human culture still has a unique status with respect to its capacity to modify natural selection. The examples the authors have given of "ecological inheritance" in non-human species are still modifications of the environment based in instinctive behavior. Human culture creates non-instinctive behavior that not only modifies the environment and natural selection, but the behaviors themselves are passed on externally to the body, through symbols and education directly, not indirectly by the remaining modified niche. There is still a qualitative difference in the way that human culture can modify natural selection. A beaver can leave behind a dam that will modify the environment of the next generation of beavers. But a beaver can't leave behind a blueprint or even better a description in words, of how to build a dam to he next generation. Marx's little ditty in _Capital_ on the difference between the construction by a spider or a bee is still a good rule of thumb on this. The human builder , unlike the spider or the bee, builds in imagination first, has a plan. The enormity of the "imaginary plans" , culture, tradition, custom, that humans accumulate and pass on has gone from a quantitative difference to a qualitative difference with animal transgenerational transfers. An animal can pass on an emblem ( a dam) , but only a human can pass on a symbolic description of how to build a dam. CB _______________________________________________ Crashlist resources: http://website.lineone.net/~resource_base To change your options or unsubscribe go to: http://lists.wwpublish.com/mailman/listinfo/crashlist
