Biomedical subjects

Daniel M T Fessler

Publications and source records attributed to Daniel M T Fessler.

9 recordsLinked to original sources

PubMed2005

Examining the terminal investment hypothesis in humans and chimpanzees: associations among maternal age, parity, and birth weight.

The terminal investment hypothesis (Williams [1966] Adaptation and Natural Selection; Princeton, NJ: Princeton University Press) holds that reproductive effort should increase over time in iteroparous species in which reproductive value declines with age. Attempts to model this hypothesis and test it in various species have produced mixed results. Clutton-Brock ([ 1984] Am. Nat. 123:212-229) argued that simply testing for changes in propagule size with age fails to recognize that the costs of producing offspring of a given size may increase over the lifespan, hence absence of a positive correlation does not defeat the hypothesis. However, this interpretation is weakened by evidence of sequential increases in propagule size independent of age, as such changes reveal a capacity to increase absolute investment over time. Humans and chimpanzees meet the preconditions of the terminal investment hypothesis. Surveying the obstetrics literature, we show that the majority of published studies indicate that parity has a positive effect on birth weight, but age has no effect. Analyzing 436 captive chimpanzee births, we document a positive influence of parity and a negative influence of age. We therefore conclude that, though it is yet to be replaced by a more compelling alternative, the terminal investment hypothesis is not supported in these two species, as absence of a positive effect of age on birth weight cannot be interpreted in a manner congruent with the hypothesis.

Age Factors↗

PubMed2005

A cross-cultural investigation of the role of foot size in physical attractiveness.

Disparate cultural practices suggest that small foot size may contribute to female attractiveness. Two hypotheses potentially explain such a pattern. Sexual dimorphism in foot size may lead observers to view small feet as feminine and large feet as masculine. Alternately, because small female feet index both youth and nulliparity, evolution may have favored a male preference for this attribute in order to maximize returns on male reproductive investment. Whereas the observational hypothesis predicts symmetrical polarizing preferences, with small feet being preferred in women and large feet being preferred in men, the evolutionary hypothesis predicts asymmetrical preferences, with the average phenotype being preferred in men. Using line drawings that varied only in regard to relative foot size, we examined judgments of attractiveness in nine cultures. Small foot size was generally preferred for females, while average foot size was preferred for males. These results provide preliminary support for the hypothesis that humans possess an evolved preference for small feet in females.

Adult↗

PubMed2004

The relationship between susceptibility to nausea and vomiting and the possession of conditioned food aversions.

Because nausea and vomiting play an important role in the formation of conditioned food aversions, individual differences in susceptibility to nausea and vomiting may contribute to interindividual variation in conditioned food aversion acquisition. Two surveys reveal that, among female participants, self-reported motion sickness susceptibility is positively correlated with the number of conditioned food aversions possessed, but no such correlation appears among male participants.

Adult↗

PubMed2004

Infant mouthing behavior: the immunocalibration hypothesis.

Avid mouthing, the propensity of infants to suck objects and put them in their mouths, is a pattern characteristic of the first 2-3 years of life, with its most intensive manifestation occurring during the first year. Although traditional accounts explain infant mouthing as a source of sensual gratification and/or environmental exploration, these proximate hypotheses are inconsistent with the high costs of mouthing, including choking, poisoning, and exposure to pathogens. We propose that mouthing serves to proactively expose the naive gastrointestinal tract to environmental antigens and commensal bacteria while under the sheltering umbrella of breastfeeding. Mouthing functions to accurately calibrate the developing immune system, including antibody production and mucosal immunity, to the local disease ecology. The critical exposure period is not open-ended, as failure to expose the gut to an adequate number of antigens early in life is associated with an increased risk of allergies, asthma, and atopy. Weaning initiates a number of immune changes that may program the neonatal immune system into certain life-long responses.

Child, Preschool↗

PubMed2003

Disgust sensitivity and meat consumption: a test of an emotivist account of moral vegetarianism.

Emotivist perspectives on moral reasoning hold that emotional reactions precede propositional reasoning. Published findings indicate that, compared with health vegetarians, those who avoid meat on moral grounds are more disgusted by meat [Psychol. Sci. 8 (1997) 67]. If, as per emotivist perspectives, such disgust precedes moral rationales for meat avoidance, then the personality trait of disgust sensitivity should generally be inversely related to meat eating. We surveyed 945 adults regarding meat consumption, reasons for meat avoidance, and disgust sensitivity. Contrary to the emotivist prediction, (a) meat consumption was positively correlated with disgust sensitivity, and (b) individuals who reported avoiding meat for moral reasons were not more sensitive to disgust than those who avoided meat for other reasons. We conclude that moral vegetarianism conforms to traditional explanations of moral reasoning, i.e. moral vegetarians' disgust reactions to meat are caused by, rather than causal of, their moral beliefs.

Adolescent↗

PubMed2003

No time to eat: an adaptationist account of periovulatory behavioral changes.

A comprehensive review of women's dietary behavior across the menstrual cycle suggests a drop in caloric intake around the time of ovulation; similar patterns occur in many other mammals. The periovulatory nadir is puzzling, as it is not explicable in terms of changes in the energy budget. Existing explanations in the animal literature operate wholly at the proximate level of analysis and hence do not address this puzzle. In this paper, I offer an ultimate explanation for the periovulatory feeding nadir, arguing that the decrease in the set point for satiation during the fertile period of the female cycle is an adaptation produced by natural selection in order to reduce the motivational salience of goals that compete with those directly or indirectly pertaining to mating. In support of this explanation, I adduce evidence of: a) periovulatory reductions in other ingestive behaviors, and b) periovulatory increases in motor activity and the psychological concomitants thereof.

Adaptation, Physiological↗

PubMed2002

Pseudoparadoxical impulsivity in restrictive anorexia nervosa: a consequence of the logic of scarcity.

OBJECTIVE: To explain an apparently paradoxical pattern wherein sufferers of restrictive anorexia nervosa exhibit both rigorous self-restraint and episodic impulsivity. METHOD: The experimental, historical, and clinical literatures were examined for evidence of psychological and behavioral changes accompanying severe dietary constriction; such changes were noted and compared with those reported to occur in anorexics. RESULTS: Increased impulsivity in association with dietary constriction is described in diverse literatures. A number of lines of evidence suggest that the serotonergic system mediates this change. DISCUSSION: Many forms of impulsivity can be understood as having once constituted fitness-enhancing responses to resource scarcity. It is suggested that an evolved psychological mechanism calibrates the individual's sensitivity to risk in light of future prospects. Self-injurious behaviors are explicable as misfirings of such a mechanism. Similarly, excessive exercising by anorexics may reflect the misdirection of reward systems that normally encourage adaptive increases in ranging behavior under conditions of scarcity.

Animals↗

PubMedDate not supplied

Sexual dimorphism in foot length proportionate to stature.

BACKGROUND: The preponderance of existing results suggests that, relative to stature, women have smaller feet than men. However, several investigations indicate that the relationship between foot length and stature may be curvilinear, a pattern that, due to the dimorphic nature of stature, would mask the true direction of pedal sexual dimorphism in published results. AIM: The study aimed to determine whether proportionate foot length is sexually dimorphic and, if so, the nature of that dimorphism. MATERIALS AND METHODS: Surveying genetically disparate populations (USA, Turkey, and Native North and Central American), we examined data from three previous anthropometric studies (Davis 1990, Parham et al. 1992, Ozaslan et al. 2003) and foot tracings from the Steggerda Collection at the US National Museum of Health and Medicine. Analyses explored sex differences in the ratio between foot length and stature, and tested for nonlinearity. RESULTS: Although varying in degree across populations, proportionate to stature, female foot length is consistently smaller than male foot length. CONCLUSION: Given the biomechanical challenges posed by pregnancy, smaller female proportionate foot length is somewhat surprising, as foot length affects dorsoventral stability. It is possible that the observed pattern reflects intersexual selection for small female foot size, a cue of youth and nulliparity.

Body Height↗

PubMedDate not supplied

Dimorphic foraging behaviors and the evolution of hominid hunting.

In contemporary foraging societies men typically hunt more than women. This observation has played an important role in many reconstructions of hominid evolution. The gender difference in human hunting, likely a product of both ecological and cultural factors, is mirrored by a similar sex difference among nonhuman primates. Existing explanations of such primate behavioral dimorphism are augmented by the recognition of an additional factor that may contribute to differences between males and females in the value of meat. Episodic female immunosuppression is a normal part of reproduction. Because meat is a source of pathogens, females can be expected to exhibit less constant attraction to meat. Sexual dimorphism in the attraction to meat may then contribute to dimorphic foraging specializations, a divergence that is likely augmented by the differential value of insectivory across the sexes. With the rise of cultural transmission of foraging knowledge, dimorphic foraging behaviors would have been reinforced, creating a more comprehensive gender-based division of labor.

Animals↗