Papers by Margaret Weigel
Ethology and Sociobiology, 1987
Polyandry has occurred rarely among humans; and has almost always consisted of brothers sharing a... more Polyandry has occurred rarely among humans; and has almost always consisted of brothers sharing a wife. The reduced opportunity for fertilization of females that occurs in polyandry would appear to make it a maladaptive mating system for human males. Previous evolutionary studies of human polyandry have suggested that kin selection may play a role in maintaining polyandry in some populations. A mathematical model for determining the fitness of polyandry for males is presented, and a simple deterministic analytic solution is derived. The model indicates that for polyandry to he an adaptive alternative to monogamy, the number of surviving offspring must be greater than the number of surviving offspring under monogamy times the number of males sharing a wife. This model exists in the literature. The unrealistic assumptions made in deriving this simple equation are revealed. An alternative stochastic computer simulation model is presented. The reproductive life history of a set of brothers is simulated under different demographic conditions, using data from polyandrous societies to estimate probabilities of fitness-related events. Under the assumption of equality of values of demographic variables for polyandry and monogamy, polyandry achieved or exceeded fitness parity with monogamy one third of the time. This contrasts with the prediction of the deterministic model stating that polyandry will never be an adaptive alternative to monogamy when fitness-related parameters are equal. The conditions improving fitness expectations for polyandry are conditions where genetic replication is decreased, i.e., with fewer brothers, high female sterility, decreased offspring survival, and decreased female fertility. Also, increased age difference between brothers enhances the fitness of polyandry. Genetic relatedness between brothers did not significantly affect the fitness of polyandry; therefore the kin selection hypothesis does not receive support. To a certain degree, these conditions exist for polyandrous populations in the Himalayas. Multivariate statistical analyses of simulation results revealed that most of the effects of these demographic factors could be accounted for by their association with increased probability of household extinction under monogamy and increased number of years of reproductive monogamy within polyandry. Although conditions favoring polyandry could be specified, analysis of the correlation between adaptiveness of polyandry and amount of genetic replication revealed that the demographic conditions favoring polyandry also lead to family extinction. Deficiencies in the model are discussed. It is suggested that future studies identify the advantages polyandry may have over monogamy in the values of demographic variables (e.g., increased offspring survival, increased extramarital reproduction), and take a multigenerational approach.
Journal of Ethnopharmacology, 1988
Tanaka K; Ono T; Umeda M JPN. J. CANCER RES./GANN; 78/8 (819-8251/1987/ The effect of quercetin, ... more Tanaka K; Ono T; Umeda M JPN. J. CANCER RES./GANN; 78/8 (819-8251/1987/ The effect of quercetin, a flavonoid, on the in vitro transformation of BALB 3T3 cells was examined. Quercetin at a low concentration (5 mug/ml) markedly suppressed the promoting action of 12-O-tetradecanoyl phorbal-13acetate (TPA, 10 nglmll in this transformation system using 20methylcholanthrene (MCA, 1 mug/ml) as the initiator. At a concentration higher than 5 muglml, however, quercetin enhanced transformation by MCA. Quercetin itself was found to induce direct transformation, weakly, but definitely, at a slightly higher concentration than that for enhancing MCA-induced transformation. The results indicate that quercetin has pleiotropic effects on the transformation of BALB 3T3 cells.
Tropical Medicine & International Health, 1997
An epidemiologic survey (n=466) was conducted in an area of subtropical rainforest in north-west ... more An epidemiologic survey (n=466) was conducted in an area of subtropical rainforest in north-west Ecuador with the following objectives: (1) to determine the prevalence of cutaneous leishmaniasis (CL), (2) to identify the Leishmania species causing human disease, (3) to investigate the major clinical manifestations of leishmaniasis, (4) to study cellular and humoral immune response indicators associated with disease status and (5) to identify risk factors for CL. Fourteen per cent of subjects had parasitologically confirmed CL; 33% had evidence of prior disease. However, 17.2% of subjects with a negative CL clinical history presented with a positive Montenegro skin test (MST), indicating the possibility of subclinical infection. The species isolated from subject lesions were L. guyanensis (63%), L. panamensis (33%), and L. brazilensis (4%). Mean specific anti-Leishmania IgG and IgM OD serum levels were highest in subjects diagnosed with current CL, followed by those with prior CL, and were lowest in healthy subjects, respectively (0.56 0.27 vs 0.33 0.2 vs 0.22 0.14; F-ratio=74; P<0.00001) and (665 270 vs 481 220 vs 301 128.5; F-ratio=37; P<0.00001). Likewise, subjects with present CL had measurably higher MST reactions (13 6.7 mm) than those with prior CL (10.9 7.8 mm) or healthy individuals (2.4 2.5 mm; F-ratio=106; P<0.00001). Serum concentrations of IgG were predicted by lesion number (t=2.5; P=0.018), size (t=3.7; P=0.0006), and duration (t=3.5; P=0.0013). Furthermore, the MST induration size increased as a function of lesion number (t=3.0; P=0.005) and size (t=3.4; P=0.022). Subject age and sex did not predict serum IgG or IgM concentrations or MST reactions in the 3 disease groups. Although no sex differences were found with respect to clinical characteristics, children^12 years of age were almost 3 times more likely to have CL lesions or scars located on the face and head area compared to adults (OR=2.75; 95% CI=1.4-5.6, P=0.004). The risk factors associated with disease included age under 5 years (AOR=1.5; 95% CI=0.48-2.35), male gender in adults (AOR=2.8; 95% CI=1.1-7.8), and wood and/or cane exterior house walls (AOR=1.8; 95% CI=1.4-2.5). In contrast, electric home lighting was associated with decreased risk (AOR=0.7; 95% CI=0.4-2.3). The results suggest that it may be possible to modify a portion of the risk of CL by making changes in the housing environment which may help to reduce the amount of human-vector contact.
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Papers by Margaret Weigel