Human evolution theory utilizing concepts of neoteny & female sexual selection
An etiology of neuropsychological disorders such as autism and dyslexia, and the origin of left handedness.
"Pan paniscus shows increase female receptivity, variability in copulatory position, male or female initiation of sexual behavior, differential male and female preferences for copulatory position, and association of food sharing and sexual behavior. Their sexual behavior appears to function in proximate terms as a tension-reduction mechanism. Lowered tension, in turn, facilitates multi-male, multi-female social groups. Lowered levels of aggression and increased sexual activity appear to be associated with paedomorphism, and the behavioral and anatomical/physiological characteristics of the species appear to be a consequence of a feeding ecology that promotes large groupings of the animals at preferential and comparatively rich feeding sites." (Blount, Ben G. (1990) Issues in bonobo (Pan paniscus) sexual behavior. American Anthropologist 92: 702)
"The aspects of Pan paniscus anatomy most readily perceived as paedomorphic are the face-jaw complex and the neurocranium. The bonobo skull resembles that of the adolescent chimpanzee (Coolidge, 1933), and in comparison to adult chimpanzees, bonobos have smaller mandibles, reduced prognathism, and a more glogular cranium (Johnson 1981)." (Blount, Ben G. (1990) Issues in bonobo (Pan paniscus) sexual behavior. American Anthropologist 92: 707)
"The relationship between paedomorphized morphology and behavior are not entirely clear but are probably reflected in the high degree of sociability reported for the bonobos. In comparison to chimpanzees, bonobos exhibit reduced rates of aggression, especially severe aggression among males (Kuroda 1979, 1980; Mori 1984)." (Blount, Ben G. (1990) Issues in bonobo (Pan paniscus) sexual behavior. American Anthropologist 92: 708)
"What does the available evidence about Pan paniscus sexual behavior tell us about the phylogeny of the panid-hominid taxa? The primary message is that parallel evolution can produce similar anatomical and behavioral results. Selection for paedomorphism has long been thought to be an aspect of hominization, and increased sociality, sexual receptivity, and related morphological changes have been viewed as correlates. Paedomorphism "led" to striking similarities in the two species. As a further similarity, it is possible that in bonobos and in protohumans paedomorphic-derived behavior maximized access to food resources in male-female groups." (Blount, Ben G. (1990) Issues in bonobo (Pan paniscus) sexual behavior. American Anthropologist 92: 710)