Human sperm competition: ejaculate adjustment by males and the function of masturbation

  title={Human sperm competition: ejaculate adjustment by males and the function of masturbation},
  author={R. Robin Baker and Mark A. Bellis},
  journal={Animal Behaviour},
. Sperm competition theory argues that the number of sperm inseminated into a female by a male is a trade-off between two opposing pressures. On the one hand, the risk that sperm may find themselves in competition with the sperm from another male favours the male inseminating more sperm. On the other hand, ejaculates are costly to produce and males are favoured who economize over the number of sperm inseminated. This paper analyses: (1) sperm numbers and other ejaculation data for 35 human… 

The First Ejaculation: A Male Pubertal Milestone Comparable to Menarche?

The answer to the title question remains contentious, but open topics for future research are noted throughout the article as essential steps towards attaining a better understanding of thorarche.

Measuring sperm backflow following female orgasm: a new method

This method could allow females to test an aspect of sexual response that has been linked to lowered fertility in a home setting with minimal training and needs to be replicated with a larger sample size.

The Adaptive Function of Masturbation in a Promiscuous African Ground Squirrel

It is suggested that masturbation in this species was not a response to sperm competition nor a sexual outlet by subordinates that did not copulate, and instead masturbation could function as a form of genital grooming.

Adaptation to Sperm Competition in Humans

Psychological, behavioral, physiological, and anatomical evidence indicates that men have evolved solutions to combat the adaptive problem of sperm competition, but research has only just begun to uncover these adaptations.

Sperm competition and its evolutionary consequences in humans

In this chapter, the current state of knowledge regarding human sperm competition is reviewed and sperm competition and cryptic female choice together compose postcopulatory sexual selection.

Sexual coercion and forced in-pair copulation as sperm competition tactics in humans

It is hypothesized that men’s sexual coercion in the context of an intimate relationship is related positively to his partner’'s perceived infidelities and that men's sexual coercion is related negatively to their mate retention behaviors (behaviors designed to prevent a partner”s infidelity).

Pavlovian conditioning alters reproductive fitness in sperm competition and sperm allocation paradigms

It has been shown that Pavlovian conditioning provides reproductive advantage in both sexual competition and sperm allocation paradigms, independent of other factors emphasized in previous explanations, and were probably mediated by an impact on how sperm were released from sperm stores.

Sex Differences in Sexual Psychology Produce Sex-Similar Preferences for a Short-Term Mate

Men reported a greater likelihood than did women of pursuing a casual sexual relationship and it was predicted and found that men prefer short-term sex partners who are not already involved in relationships and hence present a relatively low risk of sperm competition.

Patterns of courtship behavior and ejaculate characteristics in male red-winged blackbirds

It was found that the recent copulatory behavior of males did not affect the propensity to copulate with a model female, and it was hypothesized that polygyny and sperm competition in this species have combined to select for rapid replenishment of the seminal glomera throughout the day.



Human reproductive behaviour : a Darwinian perspective

Human mating and parenting behaviors are examined from a Darwinian perspective in this collection of 20 papers by anthropologists biologists and psychologists. The emphasis is on studies using

Nonparametric Statistics for the Behavioral Sciences.

This is the revision of the classic text in the field, adding two new chapters and thoroughly updating all others. The original structure is retained, and the book continues to serve as a combined

Laboratory manual for the examination of human semen and semen-cervical mucus interaction.

This laboratory manual consists of 2 sections which describe methods of examination of human semen and semen-cervical mucus interaction in order to standardize procedures and facilitate evaluation

Sexual selection and insect sperm.

These hypotheses have 2 difficulties explaining the full range of insect sperm-to-egg ratios: i) Even in insects whose females mate only once, males transfer excess sperm, and ii) Neither specifies an advantage to females who accept excessive numbers of sperm.

Sperm competition games: raffles and roles

  • G. Parker
  • Biology
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 1990
Evolutionary games in which two males mate with the same female are examined by using an evolutionarily stable strategy (ESS) approach, which depends critically on the information available to the two competitors, and whether they occupy roles (of first or second to mate) randomly or non-randomly.