Monthly ArchiveSeptember 2006
General 29 Sep 2006 05:59 pm
Punctuated Equilibrium and the EEA for Human Behavioral Adaptations
AUTHOR: Christopher Ryan
SOURCE: Evolutionary Psychology
COMMENTARY: Allen MacNeill
The following question was asked on the Evolutionary Psychology list:
“…[W]e look to the EEA for the origins of the design of the human mind (modules, and so on) precisely because the structures in question change so slowly. If, on the other hand, it is demonstrated that complex physiological (and, presumably, psychological) structures can arise and disappear in as few as twenty generations, then of what relevance is the EEA to our discussions here?…Does Gould’s punctuated equilibria theory integrate such rapid evolutionary change? And is it accepted by the folks working in [evolutionary psychology]? If so, why do we spend so much time discussing adaptations that have likely been replaced long ago?”
To which I replied:
Eldredge and Gould, like the vast majority of other evolutionary biologists (beginning with Darwin and including such luminaries as Ernst Mayr) studied animals almost exclusively. It now appears that the equilibrium/stasis pattern that characterizes macroevolution in animals is at least partly an artifact of their developmental biology. Specifically, the hierarchical control of gene regulation in animals via homeotic genes makes possible surprisingly rapid phenotypic change without correspondingly large changes in genotype (i.e. the old “modern synthesis” has been superceded by the new “evo-devo”).
Therefore, it is quite possible (indeed, likely) that relatively slight changes in genetic regulation of development have caused the remarkable changes in hominid phylogeny reflected in the fossil record. This has already been shown to be the case for the FOX-2-P gene, and just last month for the HAR-1-F gene (see “And the winner of the fastest gene award…”), slight changes in both of which have been correlated with significant changes in the human phenotype (both in the direction of greater neoteny, by the way).
So, it is quite possible that humans have changed significantly over the past 40,000 years, and perhaps not just via purely cultural means. It is still an open question just how much of our behavior is affected by our underlying genetics, and how quickly such relationships can change (and under what conditions). And, if new research in epigenetics is any indication, such changes may be even more common and rapid than has been heretofore suspected. Nutrition during early development, chronic stress (including chronic stress in utero), and exposure to certain environmental chemicals have all been implicated in altering gene regulation, and some such alterations have been shown to be heritable (shades of Lamarck!), thereby challenging further the “standard social science model” so vilified by Pinker and other EPers.
Therefore, the EEA for some current “modules” may not date to the Pleistocene, but rather to much later periods, including (but not limited to) events in historical times. Indeed, since relative reproductive success, rather than absolute numerical differences, is the basis for natural selection (and therefore adaptation), it may be that such seemingly cultural processes as warfare, migration (including forced migration via slavery), and religious practices involving both celibacy and increased procreation (via religious prohibition of contraception) may all have played significant roles in the shaping of the human behavioral phenotype via correlated alterations in the expression of genes affecting behavior.
In a nutshell, then, the answer is yes: since humans are animals (like those studied by Eldredge and Gould), it is quite possible that punctuated equilibrium theory is applicable to human evolution, including behavioral evolution, and that further investigations into the relationship between gene regulation, development, and human behavior may yield productive, testable hypotheses about such relationships.
At the risk of blowing my own horn, I have attempted to propose such a hypothesis for the evolution of the capacity for religious experience (see: “The Capacity for Religious Experience is an Evolutionary Adaptation to Warfare”):
“The pan-specific qualities of both religious experience and warfare indicate that they are both evolutionary adaptations. There is considerable variation between individuals with respect to their capacity for religious experience and motivation to participate in warfare. Selective advantages for participation in warfare accrue to both winners and losers as long as the benefits of participation exceed the average costs. These selective advantages, primarily in the form of differential reproductive success, accrue to males when they are on the winning side in a war, and often to females no matter which side they are on.”
“Recent work on the evolutionary dynamics of religion have converged on a “standard model” in which religions and the supernatural entities which populate them are treated as epiphenomena of human cognitive processes dealing with the detection of and reaction to agents under conditions of stress, anxiety, and perceived threat. Religious experience at the individual level is characterized by depersonalization, coupled with submission to a super-individual force; the same is essentially the case for participation in warfare. The capacities for both religious experience and participation in warfare are adaptations insofar as they evolve by means of natural selection operating primarily at the level of individuals who are members of groups in which both kin selection and reciprocal altruism are also operative. It is likely that the overall patterns of supernatural organization exist as the result of coevolution between the memetic content of religious beliefs and the underlying neurological matrix within which such beliefs are maintained and transmitted in the context of specific ecological subsistence patterns.”
General 14 Sep 2006 04:01 am
News Item: Kenya Bishop Leads Anti-Evolution Fight
Evangelists Want Fossil Exhibits Kept Out Of Sight
Robin McKie, science editor
Sunday September 10, 2006
The Observer
http://www.guardian.co.uk/science/story/0,,1868955,00.html
The world’s most important collection of human fossils may soon be hidden from public view - if religious leaders get their way.
In a move that has stunned scientists, senior clergy have demanded that the bones and skulls currently exhibited in Nairobi’s National Museum of Kenya be removed from display to prevent young Africans from being corrupted.
‘It’s creating a big weapon against Christians that’s killing our faith,’ said Bishop Boniface Adoyo, who is leading the hide-the-bones campaign. ‘When children go to museums they’ll start believing we evolved from these apes.’ Not surprisingly, the bishop’s remarks have infuriated scientists who consider the museum’s collection to be unrivalled anywhere else in the world. Its fossils include those of the 4 million-year-old apeman, Australopithecus anamensis, the 1.5 million-year-old remains of the Nariokotome boy, the most complete skeleton of an ancient human ever found, and a series of other bones that highlight crucial phases of our evolutionary past.
Many of these fossils were discovered by palaeontologists Louis and Mary Leakey in areas around Lake Victoria and Lake Turkana and are generally regarded as providing stark demonstrations of how our species was shaped by natural selection.
Their son, Richard Leakey, and his wife Maeve, have continued this fossil-hunting tradition. They too have been dismayed by the bid to suppress the museum’s fossils. ‘The church is being ridiculous,’ said Richard Leakey. ‘Its leaders are out of step. Evolution theory is accepted across the world. This is scientific history and Kenya has the best of this evolutional history. Globally, few can match that claim to fame.’
The National Museum of Kenya is currently preparing to reopen next year after completing massive EU-funded renovations. As part of that work a special exhibit, The Origins Of Man, which displays the key finds around Africa’s Great Rift Valley - considered by many the cradle of humanity - is now being set up.
However, it is this display that African evangelicals say they find offensive, because it promotes Darwin’s theory of evolution. As a result, they are demanding that the display be removed or at least shunted to a less prominent location.
‘When museums put it out there that man evolved from apes, theologically they are affecting many people who are Christians, who believe God created us,’ says Bishop Adoyo, the chairman of the Evangelical Alliance of Kenya, which claims to represent churches of 35 denominations with nine million members.