Eye-tracking techniques were used to measure men's attention to back- posed and front-posed i... more Eye-tracking techniques were used to measure men's attention to back- posed and front-posed images of women varying in waist-to-hip ratio (WHR). Irrespective of body pose, men rated images with a 0.7 WHR as most attractive. For back-posed images, initial visual fixations (occurring within 200 milliseconds of commencement of the eye-tracking session) most frequently involved the midriff. Numbers of fixations and dwell times throughout each of the five-second viewing sessions were greatest for the midriff and buttocks. By contrast, visual attention to front-posed images (first fixations, numbers of fixations, and dwell times) mainly involved the breasts, with attention shifting more to the midriff of images with a higher WHR. This report is the first to compare men's eye-tracking responses to back-posed and front-posed images of the female body. Results show the importance of the female midriff and of WHR upon men's attractiveness judgments, especially when viewing back-po...
Men and women at Northwest University (n=751), Xi'an, China were asked to judge the attractiv... more Men and women at Northwest University (n=751), Xi'an, China were asked to judge the attractiveness of photographs of female patients who had undergone micrograft surgery to reduce their waist-to-hip ratios (WHR). Micrograft surgery involves harvesting adipose tissue from the waist and reshaping the buttocks to produce a low WHR and an ‘hourglass’ female figure. This gynoid distribution of female body fat has been shown to correlate with measures of fertility and health. Significantly larger numbers of subjects, of both sexes, chose post-operative photographs, with lower WHRs, as more attractive than pre-operative photographs of the same women. Some patients had gained, and some had lost weight, post-operatively, with resultant changes in body mass index (BMI). However, these changes in BMI were not related to judgments of attractiveness. These results show that the hourglass female figure is rated as attractive in China, and that WHR, rather than BMI, plays a crucial role in suc...
Folia primatologica; international journal of primatology, 2018
An all-male band of golden snub-nosed monkeys (Rhinopithecus roxellana) was observed for 3 months... more An all-male band of golden snub-nosed monkeys (Rhinopithecus roxellana) was observed for 3 months in the Qinling Mountains of China, in order to collect data on the frequencies and contextual significance of male-male mounting behaviour. Mounts occurred in a variety of affiliative, dominance-related and sexual contexts, which differed depending upon the ages of the males involved. Mounting behaviour in this group was mainly initiated by adults. Juveniles mounted each other in affiliative contexts (during play and prior to grooming). Adult males mounted subadult and juvenile partners in a greater variety of sociosexual contexts (dominance/rank-related interactions; reconciliation following agonistic encounters, and sometimes as a prelude to receiving grooming). However, subadults and juveniles were never observed to mount adults. In one dyad, involving an adult male and a subadult partner, mounting was more frequent and prolonged, and included bouts of deep pelvic thrusting. Two moun...
The simplistic view of nocturnal prosimians as “solitary” primates leading impoverished social li... more The simplistic view of nocturnal prosimians as “solitary” primates leading impoverished social lives is now known to be incorrect. Although many prosimians are relatively nongregarious, they occupy varied and complex social networks which are maintained by means of olfactory and vocal signals, as well as by direct encounters during nocturnal activities (Charles-Dominique, 1977; Schilling, 1979; Bearder, 1986). Bearder has defined five types of social organization among the nocturnal primates, all of which involve varying degrees of home range overlap and range size differentials between the sexes (Figure 1). Mating systems may differ from social systems, however, as has been amply demonstrated by fieldwork on diurnal anthropoid species. Examples include the existence of monogamy and polyandry in some callitrichids (Sussman and Garber, 1987; Goldizen, 1987), and multi-male influxes into one male units in Erythrocebus patas and in various Cercopithecus species (Cords, 1986; 1988). Since, in some nocturnal prosimians, the home ranges of a number of females may overlap that of a single male (e.g., in Perodicticus potto: Type 2 system in Figure 1), it is tempting to speculate that the male may monopolize sexual access to these females, producing something akin to a polygynous “one-male group”. However, this review will present evidence that sperm competition (Parker, 1970) and sexual selection by female choice (Eberhard, 1985) have influenced the evolution of the genitalia and copulatory behavior in males of many nocturnal prosimian species. It will be argued that many of these animals have “dispersed” mating systems in which females are able to mate with a number of males during the peri-ovulatory phase of the ovarian cycle.
Publisher Summary This chapter discusses the morphological development and evolutionary history o... more Publisher Summary This chapter discusses the morphological development and evolutionary history of red sexual skin, and of sexual swellings, among female catarrhines. It examines the various facets of anatomy, endocrinology, behavior, and ecology in extant primates and considers some fossil evidence of catarrhine evolution. This comparative approach offers some clues to the mystery of why sexual skin has such a peculiar, discontinuous distribution among the extant Old World monkeys and apes. The chapter explains that sexual skin may have arisen by elaboration of the same type of vulva1 swelling and pinkness that occurs during estrus in many female prosimians. This hypotbesis derives from the observations of sexual skin ontogeny and from comparative sixdies of its morphology in adult females. Sexual skin acts primarily as a sexually attractive distance cue in many species. It might therefore be adaptive in any environment where a monkey group spreads out over a wide area or fragments into subgroups. It is suggested that a complementary degree of penile elongation occur in order to facilitate mating behavior in those species, where females have prominent swellings. The prominent penis of the chimpanzee is best explained on this basis, since the sexual swelling is enormous and adds considerably to the depth of the female's reproductive tract.
Although approximately 400 extant primate species are currently known to science, only one of the... more Although approximately 400 extant primate species are currently known to science, only one of them—Homo sapiens— acts as host to the virulent sexually transmitted infection (STI) called gonorrhea. From a comparative perspective, this is surprising, given that many non-human primates, such as macaques, baboons, chimpanzees, and bonobos, typically engage in multiple-partner copulations. Such mating patterns are expected to favor the genesis and spread of STIs (Anderson, Hessel, & Dixson, 2004; Nunn, Gittleman, & Antonovics, 2000). Thus, we are ledtoaskwhygonorrheashouldhavearisenonlyinhumanbeings. The hypothesis outlined here provides a possible explanation. Gonorrhea is caused by the gram-negative bacterium Neisseria gonorrhoeae, which infects the epithelial cells of mucous membranes, includingthosewhichlinetheurethra,vagina,pharynx,andrectum.Gonorrheamaythusbe transmittedviavaginal, anal, and oral sexualcontacts (Bancroft,2009;Holmeset al., 2008; Rogstad,2011).N.gonorrhoeaewasfirst isolatedin1879,byAlbert Neisser, but since that time scores of additional Neisseria species have been described (Bennett et al., 2012). The vast majorityof thesearenon-pathogenic,however,existingasharmless commensals in the nasopharynx (Liu, Tang, & Exley, 2015). Moreover, transfer of chromosomal genes has been shown to occur between some of these harmless Neisseria species and N.gonorrhoeae(MaynardSmith,Dowson,S Rogstad, Elengasinghe, & Powles, 2015). N.gonorrhoeae may thus be likened to an‘‘invasive species,’’ in the sense that its precursor was transferred from its originalhabitat in thepharynx tonovel sites in thegenitalia,where it is less well tolerated, and causes disease. Such transfers of the pharyngeal bacteria that were ancestral toN.gonorrhoeaemost likely occurred as a result of the practice oforalsex.Humanbeingsaremuchmorepronetoengageinsuch contacts thanarethenon-humanprimates.Althoughvariouskinds of genital investigation commonly precede copulation in the prosimians, monkeys, and apes (for review, see Dixson, 2012), recorded incidences of fellatio and cunnilingus are very rare, especially for animals living under natural conditions. Thus, human sexual behavior is unusual in this respect, which may explain why gonorrhea has arisen solely inHomo sapiens. Precisely when the disease originated is uncertain—whether in biblical times or in Europe during the Middle Ages (e.g., Boyd, 1955; Morton, 1977; Vertue,1953).Eitherway,itappearsthathumanityisstilladapting physiologically to this STI, and that N.gonorrhoeae, in turn, is rapidly evolving resistance to the antibiotics with which we attempt to curb its spread (Whiley et al., 2012).
Eye-tracking techniques were used to measure men's attention to back- posed and front-posed i... more Eye-tracking techniques were used to measure men's attention to back- posed and front-posed images of women varying in waist-to-hip ratio (WHR). Irrespective of body pose, men rated images with a 0.7 WHR as most attractive. For back-posed images, initial visual fixations (occurring within 200 milliseconds of commencement of the eye-tracking session) most frequently involved the midriff. Numbers of fixations and dwell times throughout each of the five-second viewing sessions were greatest for the midriff and buttocks. By contrast, visual attention to front-posed images (first fixations, numbers of fixations, and dwell times) mainly involved the breasts, with attention shifting more to the midriff of images with a higher WHR. This report is the first to compare men's eye-tracking responses to back-posed and front-posed images of the female body. Results show the importance of the female midriff and of WHR upon men's attractiveness judgments, especially when viewing back-po...
Men and women at Northwest University (n=751), Xi'an, China were asked to judge the attractiv... more Men and women at Northwest University (n=751), Xi'an, China were asked to judge the attractiveness of photographs of female patients who had undergone micrograft surgery to reduce their waist-to-hip ratios (WHR). Micrograft surgery involves harvesting adipose tissue from the waist and reshaping the buttocks to produce a low WHR and an ‘hourglass’ female figure. This gynoid distribution of female body fat has been shown to correlate with measures of fertility and health. Significantly larger numbers of subjects, of both sexes, chose post-operative photographs, with lower WHRs, as more attractive than pre-operative photographs of the same women. Some patients had gained, and some had lost weight, post-operatively, with resultant changes in body mass index (BMI). However, these changes in BMI were not related to judgments of attractiveness. These results show that the hourglass female figure is rated as attractive in China, and that WHR, rather than BMI, plays a crucial role in suc...
Folia primatologica; international journal of primatology, 2018
An all-male band of golden snub-nosed monkeys (Rhinopithecus roxellana) was observed for 3 months... more An all-male band of golden snub-nosed monkeys (Rhinopithecus roxellana) was observed for 3 months in the Qinling Mountains of China, in order to collect data on the frequencies and contextual significance of male-male mounting behaviour. Mounts occurred in a variety of affiliative, dominance-related and sexual contexts, which differed depending upon the ages of the males involved. Mounting behaviour in this group was mainly initiated by adults. Juveniles mounted each other in affiliative contexts (during play and prior to grooming). Adult males mounted subadult and juvenile partners in a greater variety of sociosexual contexts (dominance/rank-related interactions; reconciliation following agonistic encounters, and sometimes as a prelude to receiving grooming). However, subadults and juveniles were never observed to mount adults. In one dyad, involving an adult male and a subadult partner, mounting was more frequent and prolonged, and included bouts of deep pelvic thrusting. Two moun...
The simplistic view of nocturnal prosimians as “solitary” primates leading impoverished social li... more The simplistic view of nocturnal prosimians as “solitary” primates leading impoverished social lives is now known to be incorrect. Although many prosimians are relatively nongregarious, they occupy varied and complex social networks which are maintained by means of olfactory and vocal signals, as well as by direct encounters during nocturnal activities (Charles-Dominique, 1977; Schilling, 1979; Bearder, 1986). Bearder has defined five types of social organization among the nocturnal primates, all of which involve varying degrees of home range overlap and range size differentials between the sexes (Figure 1). Mating systems may differ from social systems, however, as has been amply demonstrated by fieldwork on diurnal anthropoid species. Examples include the existence of monogamy and polyandry in some callitrichids (Sussman and Garber, 1987; Goldizen, 1987), and multi-male influxes into one male units in Erythrocebus patas and in various Cercopithecus species (Cords, 1986; 1988). Since, in some nocturnal prosimians, the home ranges of a number of females may overlap that of a single male (e.g., in Perodicticus potto: Type 2 system in Figure 1), it is tempting to speculate that the male may monopolize sexual access to these females, producing something akin to a polygynous “one-male group”. However, this review will present evidence that sperm competition (Parker, 1970) and sexual selection by female choice (Eberhard, 1985) have influenced the evolution of the genitalia and copulatory behavior in males of many nocturnal prosimian species. It will be argued that many of these animals have “dispersed” mating systems in which females are able to mate with a number of males during the peri-ovulatory phase of the ovarian cycle.
Publisher Summary This chapter discusses the morphological development and evolutionary history o... more Publisher Summary This chapter discusses the morphological development and evolutionary history of red sexual skin, and of sexual swellings, among female catarrhines. It examines the various facets of anatomy, endocrinology, behavior, and ecology in extant primates and considers some fossil evidence of catarrhine evolution. This comparative approach offers some clues to the mystery of why sexual skin has such a peculiar, discontinuous distribution among the extant Old World monkeys and apes. The chapter explains that sexual skin may have arisen by elaboration of the same type of vulva1 swelling and pinkness that occurs during estrus in many female prosimians. This hypotbesis derives from the observations of sexual skin ontogeny and from comparative sixdies of its morphology in adult females. Sexual skin acts primarily as a sexually attractive distance cue in many species. It might therefore be adaptive in any environment where a monkey group spreads out over a wide area or fragments into subgroups. It is suggested that a complementary degree of penile elongation occur in order to facilitate mating behavior in those species, where females have prominent swellings. The prominent penis of the chimpanzee is best explained on this basis, since the sexual swelling is enormous and adds considerably to the depth of the female's reproductive tract.
Although approximately 400 extant primate species are currently known to science, only one of the... more Although approximately 400 extant primate species are currently known to science, only one of them—Homo sapiens— acts as host to the virulent sexually transmitted infection (STI) called gonorrhea. From a comparative perspective, this is surprising, given that many non-human primates, such as macaques, baboons, chimpanzees, and bonobos, typically engage in multiple-partner copulations. Such mating patterns are expected to favor the genesis and spread of STIs (Anderson, Hessel, & Dixson, 2004; Nunn, Gittleman, & Antonovics, 2000). Thus, we are ledtoaskwhygonorrheashouldhavearisenonlyinhumanbeings. The hypothesis outlined here provides a possible explanation. Gonorrhea is caused by the gram-negative bacterium Neisseria gonorrhoeae, which infects the epithelial cells of mucous membranes, includingthosewhichlinetheurethra,vagina,pharynx,andrectum.Gonorrheamaythusbe transmittedviavaginal, anal, and oral sexualcontacts (Bancroft,2009;Holmeset al., 2008; Rogstad,2011).N.gonorrhoeaewasfirst isolatedin1879,byAlbert Neisser, but since that time scores of additional Neisseria species have been described (Bennett et al., 2012). The vast majorityof thesearenon-pathogenic,however,existingasharmless commensals in the nasopharynx (Liu, Tang, & Exley, 2015). Moreover, transfer of chromosomal genes has been shown to occur between some of these harmless Neisseria species and N.gonorrhoeae(MaynardSmith,Dowson,S Rogstad, Elengasinghe, & Powles, 2015). N.gonorrhoeae may thus be likened to an‘‘invasive species,’’ in the sense that its precursor was transferred from its originalhabitat in thepharynx tonovel sites in thegenitalia,where it is less well tolerated, and causes disease. Such transfers of the pharyngeal bacteria that were ancestral toN.gonorrhoeaemost likely occurred as a result of the practice oforalsex.Humanbeingsaremuchmorepronetoengageinsuch contacts thanarethenon-humanprimates.Althoughvariouskinds of genital investigation commonly precede copulation in the prosimians, monkeys, and apes (for review, see Dixson, 2012), recorded incidences of fellatio and cunnilingus are very rare, especially for animals living under natural conditions. Thus, human sexual behavior is unusual in this respect, which may explain why gonorrhea has arisen solely inHomo sapiens. Precisely when the disease originated is uncertain—whether in biblical times or in Europe during the Middle Ages (e.g., Boyd, 1955; Morton, 1977; Vertue,1953).Eitherway,itappearsthathumanityisstilladapting physiologically to this STI, and that N.gonorrhoeae, in turn, is rapidly evolving resistance to the antibiotics with which we attempt to curb its spread (Whiley et al., 2012).
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Papers by Alan F Dixson