A modest proposal: displacement activities as an indicator of emotions in primates

BALB/c mice: low sociability and other phenotypes that may be relevant to autism.

Successful reconstruction of any aspect of human evolution ideally requires broad-based comparisons with other primates, as recognition of general principles provides a more reliable foundation for inference. Indeed, in many cases it is necessary to conduct comparisons with other placental mammals to test interpretations. This review considers comparative evidence with respect to the following topics relating to human reproduction: (1) size of the testes, sperm, and baculum; (2) ovarian processes and mating cyclicity; (3) placentation and embryonic membranes; (4) gestation period and neonatal condition; (5) brain development in relation to reproduction; and (6) suckling and age at weaning. Relative testis size, the size of the sperm midpiece, and perhaps the absence of a baculum indicate that humans are adapted for a mating system in which sperm competition was not a major factor. Because sizes of mammalian gametes do not increase with body size, they are increasingly dwarfed by the size of the female reproductive tract as body size increases. The implications of this have yet to be explored. Primates have long ovarian cycles and humans show an average pattern. Menstruation is completely lacking in strepsirrhine primates, possibly weakly present in tarsiers and variably expressed in simians. The only other mammals reliably reported to show menstruation are bats. Three hypotheses have been proposed to explain the evolution of menstruation (eliminating sperm-borne pathogens; reducing the metabolic cost of a prepared uterine lining; occurrence as a side-effect of physiological changes), but no consensus has emerged. Copulation at times other than the periovulatory period is not unique to humans, and its occurrence during pregnancy is widespread among mammals. Although the human condition is extreme, extended copulation during the ovarian cycle is the norm among simian primates, in stark contrast to prosimians, in which mating is typically restricted to a few days when the female is in oestrus. The model of regular mid-cycle ovulation in simians is questionable. Gestation periods calculated on that basis show greater variability than in other mammals, and evidence from laboratory breeding colonies indicates that an extended mating period is matched by an extended period in which conception can occur. New evidence indicates that the noninvasive placentation found in strepsirrhine primates is not primitive after all. Furthermore, comparative studies reveal that such noninvasive placentation is not "inefficient". Evolution of highly invasive placentation in haplorhine primates is probably linked instead to immunological factors. Primates have relatively long gestation periods, and humans are average in this respect. However, there is evidence that humans show greater maternal investment during pregnancy in comparison with apes. Although the human neonate matches the typical precocial pattern of primates in most respects, a fetal pattern of brain growth continues for a year after birth, such that the human infant is "secondarily altricial" in terms of its dependence on parental care. Nevertheless, the "natural" lactation period of humans is probably about 3 years, fitting the expectation in comparison to other hominoids.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ajpa.20734

The evolution of human reproduction: A primatological perspective

In a laboratory environment, aggressive interactions between male mice may exceed normal levels leading to negative effects both on the well-being of the animals and on the validity of experimental results. In this paper we review results from the literature and our own research with regard to coping with excessive aggressive behaviour in male laboratory mice. Based on this review practical recommendations concerning the housing and care of male laboratory mice are formulated. In short, it is recommended to avoid individual housing, to transfer odour cues from the nesting area during cage cleaning and to apply nesting material as environmental enrichment. Furthermore, group size should be optimized to three animals per cage. Further research, in particular into the effects of frequency, duration, type and severity of disturbances during an experiment on the degree of aggression, is recommended.

https://lan.sagepub.com/content/37/4/300.full.pdf

Male management: Coping with aggression problems in male laboratory mice.

Social approach-avoidance behavior of inbred mouse strains towards DBA/2 mice.

Social structure features in three inbred strains of mice, C57Bl/6J, Balb/cj, and NIH: a comparative study.

The ovarian cycles of four adult female spider monkeys (Ateles geoffroyi) were followed daily throughout 30 days by means of vaginal swabs and blood samplings. Cytological analyses of the vaginal swabs and radioimmunoassay determination of the daily levels of estradiol-17 beta (E2) and progesterone (P4) wer done in order to classify the kind of ovarian cycle of this species. Our results show that Ateles geoffroyi females display menstrual cycles of about 24 days on average. By comparison with the well-known menstrual cycles of women, apes, and Old World monkeys, the four distinctive cytological phases (bleeding, follicular, periovulatory, and luteal) could be recognized; mid-cycle E2 peaks followed by mid-luteal increases of the same hormone were present in all four females. P4 levels were higher after the E2 peak, although both hormones were present throughout the cycles. Also, age-dependent features, hormone profiles, and changes in menstrual phases lengths were detected.

Lilian Mayagoitia

Papers

Social structure features in three inbred strains of mice, C57Bl/6J, Balb/cj, and NIH: a comparative study.

The menstrual cycle of the spider monkey (Ateles geoffroyi)

Psychopharmacologic analysis of an alleged oneirogenic plant: Calea zacatechichi

Self and Social Grooming in Stump-Tailed Macaques: Effects of Kin Presence or Absence within the Group.

Sex differences in intra-group spacing behaviour in stumptailed macaques (Macaca arctoides).