PART XI — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS 



ferences. Australian aborigines lose 

 heat to permit a lower temperature in 

 their extremities; Eskimos quickly 

 warm their fingers in an ice bath; 

 Africans sometimes sweat less in re- 

 sponse to heat. All of this is blithely 

 called adaptation, with the presump- 

 tion that it has a genetic basis. This 

 work is comparable in method, theory, 

 and genetic bias to the studies of psy- 

 chological differences, many of which 

 have involved "IQ" tests that purport 

 to tind racial differences in intelli- 

 gence. The logic of such studies is 

 that genetic adaptations to environ- 

 mental differences must exist, and the 

 only problem is to discover them. 



The result of these extensions of 

 the concept of genetic adaptation has 

 been to take a well-defined concept 

 and make it a hodgepodge for any- 

 one to use. To an extent, this is char- 

 acteristic of areas of science that are 

 developing rapidly or are in fer- 

 ment — and behavioral and physio- 

 logical genetics are certainly doing 

 that. The major confusion results 

 from the use of structural differ- 

 ences — i.e., genes — to describe func- 

 tional or behavioral differences, with- 

 out recognition that vast differences 

 in behavior are the result of the 

 environment or of other kinds of 

 "adaptation" to the environment. 



Perhaps we are back to the old 

 nature-nurture controversy, but there 

 has been some progress. Great strides 

 have been made in the analysis of 

 behavior by the methods of quantita- 

 tive genetics, and these methods can 

 be applied to physiological differences 

 to some extent. But the measure 

 of genetic determination — heritabil- 

 ity — applies only to the population 

 studied and to the differences among 

 the individuals within it. Within any 

 population, as well as between popu- 

 lations, individuals vary in response 

 to any biological and psychological 

 test. William has continually stressed 

 the uniqueness of the individual for 

 just about anything biological that 

 one can measure. And it is true that 

 tests of biological relatives indicate 

 that some of this variation is due to 



heredity. But it is a totally different 

 problem to explain differences be- 

 tween populations. It seems reason- 

 able to most people that these dif- 

 ferences must also have about the 

 same genetic component; but that is 

 not the case. 



We are only just beginning to 

 realize how powerful environmental 

 influences are in affecting the total 

 functioning of the individual. "Adap- 

 tation" — whether to temperature 

 change, to disease, to crowded con- 

 ditions, to learning school work — 

 results from spending one's lifetime 

 in a particular environment; putting 

 two different groups in the same 

 cold chamber, school, or hospital for 

 a day, a week, or even a year is not 

 a "controlled" experiment that will 

 prove genetic or racial differences. 

 For example, it was long thought that 

 "natives" had a natural resistance 

 to some diseases and whites to others 

 such as TB. However, we are now 

 seeing that resistance is a function of 

 previous exposure, amount of ex- 

 posure, and age at exposure; sim- 

 plistic notions of racial immunities 

 are not very realistic. 



One cannot say, however, that sig- 

 nificant differences do not exist or 

 that there are no genetic factors in- 

 volved. American Negro troops in 

 Korea did suffer four times as much 

 from frostbite as whites; this is a 

 problem that needs explaining. Amer- 

 ican and West African Negroes do 

 seem to have an almost total resist- 

 ance to vivax malaria, which also 

 seems to be genetic. Many of the 

 populations in Europe and Africa 

 that depend on milk for subsistence 

 have an active lactase enzyme (among 

 adults), while most of the rest of 

 the world's populations are lactase 

 deficient. Nevertheless, most of the 

 behavioral differences among popu- 

 lations that have been called adapta- 

 tions do not require or demonstrate 

 genetic differences; rather, they have 

 been proposed on the basis of tenuous 

 data and a misunderstanding of the 

 populational significance of adapta- 

 tions. 



Applicability of Animal Ethology 



There is one other area of research 

 in which the concept of adaptation 

 has played an important role. This 

 is the application of animal ethology 

 to human characteristics. Lorenz on 

 aggression, Ardrey on territoriality, 

 Morris on sexual behavior, and others 

 on all other kinds of behavioral traits 

 have attempted to develop adaptive, 

 or "Darwinian," explanations for 

 these traits. Ethology in its methods 

 and theories is quite comparable to 

 behavioral genetics, although the lat- 

 ter concentrates on human data while 

 the former generalizes to man on the 

 basis of analogy with animals. 



To show that man is comparable 

 to the other animals in many ways 

 is commendable, but it is still impos- 

 sible to explain the variation in hu- 

 man behavior among populations by 

 biological or genetic factors. Aggres- 

 sion is not universal among human 

 populations; and it is the variability 

 in this characteristic that is the an- 

 thropologist's problem. To disregard 

 this variability — as does Morris, for 

 example, by saying that the rest of 

 the world's cultures are evolutionary 

 backwaters — is simply fatuous. 



As any other species, however, 

 man does have some species-specific 

 characteristics; and these are un- 

 doubtedly due to a long period of 

 adaptation to a common ecological 

 niche, which in his case was hunting 

 with tools on the savannahs of the 

 Old World. But again, to explain 

 what is "wrong" with human socie- 

 ties today by genetic lag is not ade- 

 quate. If it were, then all human 

 societies should have these aggressive 

 genes stemming from our carnivorous 

 past. But not all societies are as 

 aggressive as ours. Most ethology- 

 oriented scientists seem to view man's 

 cultural evolution as simply social 

 change which adjusts culture to man's 

 biological "needs." This view tends 

 to detract from the power of the 

 environment to change human char- 

 acteristics — if one can view cultural 

 pressure as the environment. It also 



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