SISTEMAS DE RECUBRIMIENTOS

The motivation to look for the nonartifactual ideal was to account for the ontogenic acquisition of function as typified by non-imitative learning. However, the wheelbarrow case above should suggest that the applicability of the ideal in explaining the progressive acquisition of function is wider than that. Since the villagers in the wheelbarrow case are, I assume, human, it would be wrong to explain the production of wheelbarrows by appeal to reproductive heritability. Children copying wheelbarrow design from parents is, rather, likely to be a sociogenic mechanism, just as the rats from the previous chapter copied the feeding behavior of other rats in their community. What we are observing in the wheelbarrow case looks to be social evolution and within that social setting the progressive acquisition of function. Now the wheelbarrow case is just make believe on my part, and it is was designed to present the appearance of progressive acquisition of function. So, I make no claim that human social structures do progressively

develop in that way. That said, the wheelbarrow case does demonstrate that it is plausible to think that whole groups – either social or cladistic – can progressively acquire function in the way typified by individualistic learning.

I want to take up the last point just in respect to phylogeny. It is, of course, a mistake to think that evolution as a whole is progressive. The reversibility of trait polarity87or genetic drift are both easy counterexamples to the thought that evolution as a whole is a progressive process. That said, certain tracts of evolutionary history in which there is the gradualistic acquisition of function are, I think, rightly construed as progressive. That is, such periods of phylogenic acquisition can be understood as literally for the purpose of acquiring some phylogenic function or trait. They are so, because the clade is sensitive to the end of that acquisitional process. In such cases, assuming the conditions for a nonartifactual ideal are met, it is plausible to view the clade as a whole as genuinely learning.

Take, for example, the fennec fox, a desert-dwelling fox of northern Africa with a number of desert-oriented adaptations. One of these adaptations is its overly large ears relative to other foxes. The increased size of the ear contributes to the fennec fox’s capacity to cool itself in the scorching deserts where it makes its home. (See Lariviere 2002 & Sheldon 1992) It is not unreasonable to suppose that the history of the fennec fox in northern Africa (from the non-desert adapted, progenitor fox entering northern Africa in the late Pleistocene to the present population) is one of a series of gradualistic increases in ear size and, consequently, a series of gradualistic improvements in the thermoregulatory function of the ear.

The thermoregulatory function of the progenitor fox’s ear was suboptimal. That is, when the progenitor fox entered northern Africa, there was a possible phylogenic trait, namely an increased ear, that would have maximized the benefits of the thermoregulatory function relative to other costs. That optimal phenotype was possible in that there was an available sequence of reproductive events that would take the progenitor fox to a descendent fox with the genomic structure that would produce the overly large ear. That there was, say, some initial gradualistic improvement in ear size available to the progenitor fox population did not cause the progenitor fox population to start producing foxes with that improvement. Such a gradualistic improvement was available given the facts about the genomic structure of the progenitor fox population and its reproductive strategy. The explanation why the improvement came into existence reflects those facts alone. Once, however, such a gradualistic improvement comes into existence, the increased fitness afforded by the improved thermoregulatory function does explain why the population distribution of the fox shifts over time in the direction of the improvement. Further, once the initially improved fox has come into existence, there is from that fox a further available improvement in function. That is, the facts about the newer fox’s genomic structure and reproductive strategy make available through a reproductive event a fox with a genomic structure that would produce a further still improved ear. Again, once a further improved fox came into existence, the subsequent shift in the population distribution toward that improvement would be explained by the fact that the further improvement is an improvement. We can have, then, a series of gradualistic improvements from the progenitor fox to the present population and can explain the series of transitions in respect to dominant phenotypes by the increasing improvement in

the thermoregulatory function of the ear. During that history, there would have likely been at certain stages the emergence of foxes with diminished or less optimal ears relative to their temporal peers. The explanation for why these foxes do not become dominant or generate a shift in population distribution will reflect the fact that they are relatively functionally worse off than their contemporaries in the population.

We could have within the history of the fennec fox a series of transformations over time leading to the present phylogenic trait, and that series of transformations in the dominant phenotype would be explained by improvements in the thermoregulatory function of the ear. That presents at least the appearance of the progressive acquisition of function. From what we know so far, however, we cannot say that the process of acquiring the present phylogenic trait was genuinely progress. That is, what we cannot yet say is that the process was for the acquisition of the present phylogenic trait. To say the latter, we would need some reason to think that the fennec fox through its history was sensitive to the end of that process, and we do not yet have that.

Though the sequence of shifts in dominant phenotypes is explained by the increased functionality of the ear, that could be true when the history of the fennec fox reflected genetic drift alone. For example, take some intermediate stage in the history of the fennec fox with the recent emergence of a fox with an enhanced thermoregulatory function relative to its contemporaries. That enhanced thermoregulatory function by hypothesis increases the fitness of this novel fox relative to its contemporaries. Given that this novel type of fox has a higher fitness than its contemporaries, we would expect to see the frequency distribution to shift over subsequent generations in the direction of the novel fox type. This would be true whether there was a selective regime in place or just

genetic drift. Whether selection or genetic drift were involved, it would be true that the frequency distribution shifted over time due to the higher fitness of the novel type of fox. If the history was one of genetic drift, it would not be true, however, that the quantity of members of the older type at some generational point is to due the presence of the novel type in the previous generation. Even if there were no novel type foxes around, the older type foxes would have produced the same number of descendents as they did when the novel type was present in the previous generation. In the genetic drift case, the presence or absence of the novel type is irrelevant to the explanation for why there is a certain number of the older type at a particular generational point. That quantity of older type foxes at some generational point reflects facts about the fitness value of the older type foxes. And, in the genetic drift case, the fitness value of those older type foxes is not affected by the presence or absence of the novel type.

If the history of the fennec fox was one of genetic drift, then it would present the mere appearance of progress. Whether we are considering an ideal or a non-ideal norm, the basic feature that being an exception is consequential is the same. Assuming that the older type fox is a relative exception to a putative ideal in comparison to the novel type, it will not be true in the genetic drift case that being an older type fox is consequential. That is, it will not be true that the older type fox is acted against in virtue of the fact that it is a relative exception to the putative ideal. The population of older type foxes is what it is irrespective of the presence of the more approximate instances of the putative ideal. It is not, then, in virtue of the fact that exceptions are acted against that the transition toward the novel type takes place. If the history of the fennec fox was one of genetic drift, we would not have the grounds for a normative regularity (ideal or otherwise) and,

consequently, ought to consider the apparent acquisitional progress of the fennec fox as merely apparent. Alternatively, we ought not to think that the acquisitional process of the fennec fox was for the purpose of gaining the present phylogenic trait.

In contrast, if the history of the fennec fox was a selectional history, then I think that it would be right to say that the historical process was literally for the acquisition of the present phylogenic trait. That historical acquisitional process would be for the purpose of generating the present phylogenic trait, because the clade, assuming a selective regime in place, would be sensitive to the end of that process. Unlike genetic drift, if selection on the ear’s thermoregulatory function is place, the fitness value of the older type fox is affected by the presence of the novel type fox; so, the quantity of the older type foxes at some generational point reflects the fact that there were novel type foxes in the previous generation. (The transformation from the genetic drift case to selection just requires that there is some competition for resources among fox types as well as that the likelihood of being a successful competitor reflects the difference in thermoregulatory function.) When selection is in place, simply we have the wheelbarrow case with foxes. The progenitor fox provides a normative regulatory governing the thermoregulatory function of the ear. However, that fox is functionally suboptimal, because further functional improvements on that ear are available. When they emerge, the transition or shift in the dominant phenotype is explained by the fact that the novel phenotype is literally better at the function. It is literally better, because the fact that it is a closer approximate to the ideal or optimal functional type explains why relatively less optimal types within the population are acted against. As such, the fennec fox, as a clade, is sensitive to the ideal or optimal phenotype, and the sequence of transitions in its history

would be explained by appeal to that ideal. The fennec fox, as a clade, would be genuinely learning how to improve its thermoregulatory function.