A structural comparison of female–male and female–female mounting in Japanese macaques (Macaca fuscata)

Experimentally evoked same-sex sexual behaviour in pigeons: better to be in a female-female pair than alone

“…The most common explanations include (i) social glue, which is a method to establish a strong social relationship, thereby reducing tension and conflicts 10 – 12 ; (ii) intersexual conflict, when the same-sex interaction establishes dominance in the hierarchy 13 or reduces the reproductive success of a competitor 14 ; (iii) practice, in which a young individual obtains mating experience 15 , 16 or gains the ability to improve their territory acquisition 17 ; or (iv) alloparenting, in which fluid sexuality of females may be a mechanism to possess allomothering investment from a female not related to the offspring 18 , 19 . On the other hand, non-adaptive explanations of same-sex sexual behaviour have been proposed, such as (i) mistaken identity, which explains this behaviour as an error due to lack of sex recognition 20 ; (ii) heterosexual deprivation when the population density is high and the sex ratio is skewed towards one sex 21 – 23 ; (iii) an evolutionary by-product, when selection acts on traits linked to sexual responsiveness 24 ; (iv) maladaptation if the individual is not well adapted to its environment 25 ; (v) intoxication, when methylmercury causes same-sex sexual behaviour and diminishes reproductive output as a result 26 ; or (vi) nutritional rewards, which is based on evidence that the brain network of the sexual response cycle pathway is similar to the pathway of the pleasure cycle during food acquisition, so that sex preference in later life depends on which sex was a caregiver during infancy 27 .…”

Social order: Using the sequential structure of social interaction to discriminate abnormal social behavior in the rat

“…For example, the Eshkol-Wachman Movement Notation method (Eshkol & Wachman, 1958) is a system in which body position in space and time is coded, providing a record of the temporal sequence of movements and their organization. These records can be performed separately on interacting organisms, and utilized to examine the relative spatiotemporal structure of behavior between individuals (Carrier, Leca, Pellis, & Vasey, 2015; Norman, Pellis, Barrett, & Henzi, 2015; Pasztor, Smith, MacDonald, Michener, & Pellis, 2001; Pellis, 1982). A major advantage of this system is that the topography of specific behaviors can be characterized in great detail.…”