What are the main ideas presented in this particular blog post? What evidence is presented to support the main ideas of the blog? Is there any evidence presented in the blog to refute or question the main ideas? Are there any scholarly references?
Men Masturbated For Science, And Heres What Came Of It is an article By David Freeman that was on the August 7th 2015 edition of Huffpost. It suggests that men ejaculate faster and produce more sperms of higher quality when they have sexual intercourse with an attractive woman they have never encountered before. The author does not suggest that males are inclined to be unfaithful to their spouses. However, the article may imply that they have evolved in a way that they find it easier to copulate and impregnate other women who are not their usual partners. The blog post also offers new understandings about evolutionary biology that may make it easier to detect and treat male infertility.
Among the evidence presented support the main ideas of the blog post are findings from new research carried out by scientists The College of Wooster in Ohio. The study involved an analysis of semen samples collected from 21 heterosexual males as they masturbated over seven pornographic videos. The first six videos starred the same actress while the seventh one had a different female lead. The scientists observed a sharp increase in the volume of semen ejaculated and the number of motile sperm from the subjects after watching the seventh film. Also, the time taken to ejaculate was significantly less as they watched this video.
The other evidence is gotten from males who seek treatment from fertility problems. Often, the men provide semen samples gotten while masturbating from pornographic material. Since it features actresses they have never encountered before, the sperms produced are likely to be of higher quality than usual. This may explain the potential fertility issues experienced when they cohabit with their usual partners. There is no evidence presented in the article that refutes or questions the main ideas. A journal titled Evolutionary Psychological Science is cited as a reference.
Explain the evolutionary theory that discusses sperm competition as a male reproductive strategy.
The evolutionary theory that looks at sperm competition as a male reproductive strategy is the sexual evolution theory. Brain function and the psychology that it influences is not just a result of result of evolution, but also a significant driver of this evolution. The sexual choices that people make go a long way in determining which individuals get to reproduce as well as the psychological and physical features that are favored as time goes by. In survival selection, a harsh physical environment gets rid of people who do not have a perfect form. In sexual selection, it is the humans themselves rather than the physical environment that determines the traits to be passed on (Damsgaard et al, 2016).
Sperm competition can be described as that between males to deter one another from fertilizing eggs. It is a kind of male-male competition which becomes a sexual selection made up of members of one sex that are competing to access the other sex. In principle, the competition could result in the evolution of traits such as faster swimming speeds aimed at getting at the egg earlier than the rival sperm. All in all, it can also result in evolution of numerous other traits such as mate guarding whereby a male shields a female from mating with rivals. Other traits include frequent copulation and more production of sperms to increase the likelihood of the sperm getting into the periphery of fertilization.
Explain the evolutionary theory that discusses male sexual interest in a novel (i.e. new) female.
The evolutionary theory that discusses male sexual interest in a new female is evolutionary psychology. This is a theoretical approach to psychology that tries to explain useful psychological and mental conditions as adaptations of natural selection. Simply put, evolutionary psychology gives an idea of how evolution has shaped the human mind and behavior. The theory points out that sex differences develop biologically as human beings adapt to changes in their own environment. With respect to mating preferences, this theory implies that the characteristics people look for in partners depends on their sex, and whether mating will last for a short or long time (Parker, Lessells & Simmons, 2013).
For males, emotional connection and sexual attraction are not necessarily linked together. Men are attracted to women strictly on a physical level. They can be sexually attracted to females with whom they do not feel any emotional compatibility or connection. While they can be deeply in love with one woman and completely devoted to her, they can still be attracted to other women. As a matter of fact, science suggests that there is nothing they can do about it. Research shows major differences in the manner in which males and females are attracted to potential partners. Females tend to be more drawn to males on a basis of familiarity. They prefer men who closely look like their current partner, and rate males more attractive the more often they come into contact with them. On the other hand, men are attracted to novelty. They are drawn to anything new or different; meaning they are attracted to various women having numerous different body types and features. This phenomenon has been interpreted to result from evolution. In general, women evolved to be mothers, wives, caretakers, and nurturers. Men are wired to ensure the survival of their genes by mating with as many partners as possible.
Discuss three studies from scholarly peer reviewed journal articles that discuss sperm competition in modern humans.
One study that discusses sperm competition in modern human beings is found in an article titled Psychological Adaptation to Human Sperm Competition. According to the authors, this competition takes place when the sperm of at least two males inhabit the reproductive tract of a female at the same time and engage in a competition to fertilize an egg. They used a questionnaire to find out psychological responses to the risk posed by sperm competition. They used feedback from 194 males in committed, sexual relationships living in Germany and the United States. The study found out that men who spent more time away from their partners since the couples last sexual activity reported several observations. Their partners were more attractive, other males found them more attractive, there was greater interest in sex with partners, and partners were more sexually interested in them (Shackelford et al, 2002).
In an article titled Human sperm competition: testis size, sperm production and rates of extrapair copulations, the authors set to clarify the claim that sperm competition is a crucial selection pressure present in human population. They recruited 194 females and 222 males to take part in a survey of their sexual behavior. 22% of the women and 28% of the men admitted to participating in EPCs (extrapair copulations). A review of the articles literature implies that rates of extrapair paternity are about 2%. These figures imply that the risk of sperm competition in human beings is relatively low; and matches with comparative studies of testis sizes of humans as well as other primates. The authors did not find any proof supporting a certain controversial claim which goes like the within-population frequency distribution of testis size mirrors a stable polymorphism between males who specialize in sperm competition via EPCs and monogamous men (Simmons, Firman, Rhodes & Peters, 2004).
In an article titled Sperm Competition in Humans: Implications for Male Sexual Psychology, Physiology, Anatomy, and Behavior, the authors conduct additional study on sperm competition. If two or more males have sex with a female within a short period of time, their sperms will compete for fertilization. Since the theory of sperm competition was first argued in 1984, it has been boosted with new discoveries and ideas. The authors review recent theoretical work on sperm competition in humans, identify challenges and limitations facing the research, and present the way for the future.
Discuss three non-human studies that examine sperm competition in other mammals (not bird or insects).
Ejaculate quality and constraints in relation to sperm competition levels among eutherian mammals is an article that discusses sperm competition in other mammals apart from humans. The result of sperm competition depends on the relative quantity and quality of sperm produced by competing males. It is a well-established fact that the characteristics of individual ejaculate evolves significantly during post-copulatory sexual selection. However, not much is known about the other factors that may influence the evolution of ejaculate. Lupold studied how ejaculate quality traits in eutherian mammals vary with each other and with metabolism, body size, and testis mass. He found out that all ejaculate traits co-vary with each other, and increase with relative testis mass (Lupold, 2013).
What is ONE problem with the method used in one or more of the studies you used?
Sperm competition results in psychological and morphological adaptations that help propel sperm faster. However, it may have a negative impact on DNA integrity. DNA damage in sperm is linked to reduced fertilization rates, fetal and embryo loss, mutations causing genetic disease, and offspring mortality. In A cost for high levels of sperm competition in rodents: increased sperm DNA fragmentation, the authors studied whether sperm DNA integrity is affected by high levels of competition. They evaluated integrity in 18 rodent species that exhibit different levels of sperm competition with the use of the sperm chromatin structure essay. Findings showed that sperm DNA was quite resistant to chemical and physical stressors, while incubation in capacitating and non-capacitating conditions led to only a minor increment in sperm DNA damage. An important finding was that sperm competition levels were positively linked to sperm DNA fragmentation in all rodent species (Garcia-Alvarez, Soler, Tourmente, Garde & Roldan, 2016).
Drive genes are genetic elements known to manipulate the half ratio of Mendelian inheritance in a way that suits, enabling them to quickly propagate through populations. Often, their action is discrete in a manner that makes detection and identification quite difficult. All in all, drive genes can have an adverse evolutionary effect for the populations that accommodate them. In Sperm competition suppresses gene drive among experimentally evolving populations of house mice, the authors identified the presence of a drive gene known as t haplotype post hoc in 8 replicate selection lines of house mice. This gene had been undergoing evolution under enforced polyandry or monandry for about 20 generations (Manser, Lindholm, Simmons & Firman, 2017).
One of the problems faced during one of the studies mentioned above is the objective risk of female EPC. It is measured in terms of the time between copulation activities, it significantly and positively matches with males partner directed sexual coercion. Length of time since the last sexual activity between male and female is not linked to males sexually coercive behavior. Simply put, males are not sexually forcing their partners because of sexual frustrations, but rather as a response to increased female EPC risk. In addition, this length of time matches with sexual coercion only for those males who suspect their partners of cheating on them. In the case of the men who dont suspect their partners of infidelity, there is no link between the length of time since the last copulation and sexual coercion.
How is the blog post misleading or inaccurate?
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