For women, coitus alone is insufficient for triggering orgasm, puzzling researchers who expect orgasm to be an outcome of procreative intercourse. We examine the evolutionary role for prosociality that such unreliability of orgasm at coitus might have played in human evolution

Kennedy J, Pavličev M. Female orgasm and the emergence of prosocial empathy: An evo-devo perspective. J Exp Zool (Mol Dev Evol). 2018;1–10. https://doi.org/10.1002/jez.b.22795

Abstract: In human females, direct or indirect stimulation of the clitoris plays a central role in reaching orgasm. A majority of women report that penetrative coitus alone is insufficient for triggering orgasm, puzzling researchers who expect orgasm to be an outcome of procreative intercourse. In the present paper, we turn our attention to the evolutionary role that such unreliability of orgasm at coitus might have played in human evolution. We emphasize that we do not thereby attempt an explanation of its origin, but its potential evolutionary effect. The present proposal suggests that the variable female orgasm, the position of the clitoris remote from the vagina, and the mismatch of the male refractory period with the female capacity for multiple orgasms, may have contributed to the evolution of human prosocial qualities.

---
Prosocial empathy as discussed here is an essential feature of human social life and includes the quality sometimes called intersubjectivity or mind-reading. Related to theory of mind in psychology, this is the ability of individuals to know with some accuracy what another person is thinking and how they feel. The ability seems to function differently from ordinary objective inference from perception; intersubjectivity is a low-latency process that allows nearly instantaneous understanding of others. Although it is difficult to assess intersubjectivity in nonhuman species, there is evidence that some other species are capable of it to some degree (e.g., deWaal, 2010).

The present thesis is that the anatomical separation of orgasm from the reproductive function in humans may have led to the emergence of a new kind of prosocial empathy or intersubjectivity. The fact that coitus alone is reliably sufficient for the male's but not the female's orgasm set the stage for a selection criterion where females preferred to mate with males who had a particular kind of social insight, motivation, and self-discipline that enabled them to elicit orgasm. The preferred male would have been one showing an active interest in his partner's experience; he would have the interpersonal sensitivity to identify what “works” sexually and to adjust his behavior in response to her responding, and the motivation and self-discipline to defer his own ejaculation until she had reached orgasm.We are proposing that a cluster of empathic prosocial tendencies may have come to dominance in the human species as a consequence of this sexual selection process.

That is not to say that this is the only path leading to modern human eusociality; the ability to understand how others think and feel would have introduced advantages across the range of social behaviors that helped the species overcome several fitness challenges. In the long run, we would expect the effect of human sexual asymmetry to integrate into a comprehensive schema of human sociality, as several types of selective pressures converged to produce themodern human.

A recent approach to understanding intersubjective empathy has emerged from the discovery of mirror neurons (Di Pellegrino, Fadiga, Fogassi, Gallese,&Rizzolatti, 1992), which respond when a subject performs a behavior and also sympathetically when the subject observes another individual perform that same behavior. Iacobonni (2009) has argued that neural mirroring answers the question of how humans can have access and understanding of others’ minds. According to this view, intersubjectivity ormind-reading emerges from a real-time mental simulation of the other person's behavior, with the subject literally feeling what it is like to be the other person. This simultaneous simulation can support social collaboration and interaction at a level unknown to species lacking the ability. A population of individuals sympathetically tuned to one another may produce a “shared manifold” (Gallese, 2003) comprising a communal empathic understanding of selves and others.

Mirror neuron research provoked great initial interest, which has been followed by the current phase of caution and skeptical enthusiasm asmore thorough knowledge is gained about the function of these specialized neurons in humans. Whether mirror neurons are found to be the mechanism for it or not, the concept of real-time simulation of others has suggested a new way of looking at social empathy. Citing mirror neuron research in apes and humans, deWaal (2010) emphasizes that human mind-reading abilities are continuous with those of other species. Attributing intersubjective empathy to other apes as well as humans, de Waal (2010) points to the importance of “body-mapping,” of identifying one's body with another's, where an individual can feel in their own body what the other person is experiencing in theirs. In de Waal's narrative, empathy and self-awareness are linked, and are not unique to human beings; he demonstrates the existence of empathy in elephants, dolphins, and apes, and notes that among these species it is comparable to empathy in humans.

---
Check also Gallup, G. G., Jr., Towne, J. P., & Stolz, J. A. (2017). An Evolutionary Perspective on Orgasm. Evolutionary Behavioral Sciences, www.bipartisanalliance.com/2017/11/an-evolutionary-perspective-on-orgasm.html

And: Male Qualities and Likelihood of Orgasm. James M. Sherlock, Morgan J Sidari. In T.K. Shackelford, V.A. Weekes-Shackelford (eds.), Encyclopedia of Evolutionary Psychological Science, www.bipartisanalliance.com/2018/01/male-qualities-and-likelihood-of-orgasm.html