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P T Baker

Publications and source records attributed to P T Baker.

At least 19 recordsLinked to original sources
PubMed1997

Bergmann's rule and the thrifty genotype.

One of Roberts' key contributions was his work demonstrating the applicability of several ecological rules to human populations (Roberts [1953] Am. J. Phys. Anthropol. 11:533-558; [1978] Climate and Human Variability, 2nd ed., Menlo Park, CA: Cummings). His finding that average body weight systematically covaries with mean annual temperature was widely taken as confirmation of Bergmann's rule for humans. More recently his findings on weight and temperature have been extended and confirmed (Ruff [1994] Yrbk. Phys. Anthropol. 37:65-407; Katzmarzyk and Leonard [1995] Hum Biol Council Program Abstracts 132) although the strength of the association may be decreasing when considering more recent surveys (Katzmarzyk and Leonard [1995]). Roberts noted in 1953 that Oceanic populations may be somewhat of an exception to Bergmann's rule, and we propose that Neel's ([1962] Am. J. Hum. Genet. 14:353-362) thrifty genotype model may account for some of the deviation from predicted weights among these populations. We provide an updated version of the thrifty genotype model, suggesting that selection for energetic efficiency may have occurred for some Oceanic populations during the voyaging to and settlement of their island homes. Under conditions of modernization the thrifty genotype may be manifesting as high rates of obesity and NIDDM among Polynesians and Micronesians. First, using measurements of adult male weight from 19 Oceanic populations, we demonstrate the extreme nature of their deviation from predicted weight based on Roberts' regression of weight on mean annual temperature. Next, we regress the deviations from predicted weight on NIDDM prevalence for these 19 populations, producing a highly significant regression (R2 = 0.46; P < 0.001), consistent with expectations if the thrifty genotype is responsible for the high weights.

Adult↗
PubMed1990

Modernization and catecholamine excretion of young Samoan adults.

Urinary catecholamine excretion rates have been used as a cross-culturally valid measure of generalized stress. The purposes of this paper are to examine group differences in catecholamine excretion rates in three Samoan groups who differ in degree of modernization and to compare these findings to rates of norepinephrine and epinephrine excretion in other populations. In 1986-1987, 24-hr urine samples were collected from 18-37-year-old Samoans; 46 rural Western Samoan villagers, 53 American Samoans, and 49 Samoans residing in Honolulu. The results show that norepinephrine excretion is significantly higher in more modernized Samoan groups (P less than 0.05), while epinephrine excretion is not significantly different in the three groups. The higher norepinephrine excretion rate in the more modernized Samoan groups may be related to differences in relative work load associated with changes in body weight, work capacity, and work patterns which accompany modernization. Samoan epinephrine excretion rates are relatively high compared to the results of other population studies, while norepinephrine excretion in three Samoan samples ranged from among the lowest rates observed worldwide to among the highest.

Adult↗
PubMed1987

Variation in lifestyle characteristics and catecholamine excretion rates among young Western Samoan men.

Comparisons of 13 lifestyle characteristics and the rates of urinary catecholamine excretion during typical morning activity are examined among four groups of young Samoan men in Western Samoa. The groups include 28 manual laborers, 33 sedentary workers, and 31 college students from the urban area of Apia, and 31 rural agriculturalists. Associations between the lifestyle variables and catecholamine excretion rates are also investigated in the total sample (N = 123) using correlations and multiple stepwise regression techniques. Results of the lifestyle characteristic comparisons show that the villagers have greater life satisfaction, emotional stability, agreement with Samoan customs, and familial responsibility (P less than 0.05). The catecholamine comparisons show that the villagers have lower rates of epinephrine and norepinephrine excretion than any of the Apia groups (P less than 0.05 and P less than 0.005 respectively). The regressions indicate that diet, activity, day of specimen collection and the overall lifestyle and ecological differences between the village and Apia are associated with 25 and 31% of the variation in the rates of epinephrine and norepinephrine excretion respectively. These results suggest that both psychological and habitual behavioral differences contribute to the catecholamine variation of the men in this study, and that these differences are related to the degree of participation in Western lifestyles.

Adult↗
PubMed1987

Physical activity and plasma total- and HDL-cholesterol levels in Western Samoan men.

This study examines effects of physical activity on plasma total- and high-density lipoprotein (HDL) cholesterol and derived variables in Western Samoan men who differ in rural/urban residence and occupation. Rural agriculturalists have significantly higher HDL cholesterol and HDL:total ratio than men employed in either physically active or physically sedentary occupations in an urban setting. Total cholesterol levels do not vary significantly, but when the differences in HDL cholesterol are accounted for, the means for agriculturalists and active workers are significantly lower than those for sedentary workers who do not play sports. These differences in HDL- and non-HDL-cholesterol levels are consistent with measures of physical activity among the groups. Variation in physical activity due to residence and occupation in Western Samoan men is related to lipoprotein cholesterol levels, but not to total cholesterol levels, and some effects may be secondary to differences in body composition.

Adult↗