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The Ecology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Much work is yet to be done to fully understand competition among parasites. Parasites produce secretory products that are in many cases uncharacterized and in addition to affecting host immune cells, may have direct interfering effects on conspecifics, effects we do not yet understand. Such compounds could potentially be exploited as new ways to limit parasite growth. Another intriguing consideration is that kin selection might regulate parasite populations. According to this view, established parasites may be able to detect relatives and favor their survival at the expense of unrelated individuals.
Evolution, Natural Selection, and Behavior
Published in Gail S. Anderson, Biological Influences on Criminal Behavior, 2019
Siblicide is the murder of one’s siblings. Natural selection favors traits that increase reproductive fitness, which passes these traits to the next generation. Kin selection theory predicts that relatedness should promote altruism, in that it is important to protect close relatives, such as siblings, as they carry many of the same genes that you do, so ensuring that they survive to reproduce helps you indirectly by passing on those traits to the next generation.27 This is perhaps best illustrated in a beehive, in which only one female, the queen, is fertile and all the other related females are sterile. They act as workers to raise the offspring of the queen, their mother, and in so doing, help to pass their genes on to the next generation. Siblicide therefore seems counterintuitive. However, siblings may come into conflict when competing for resources such as parental investment. This is more commonly seen in non-human animals, particularly in bird species, in which a nestling will frequently push another nestling out of the nest in order to receive more resources from the parents. Although much rarer in mammals, siblicide does occur in some species, usually when food resources are low.27 It may also have been common in our ancestral past.
Anti-Aging and Regenerative Medicine
Published in Aruna Bakhru, Nutrition and Integrative Medicine, 2018
In the early 1960s, two evolutionary mechanics theories were proposed. The British zoologist Vero Wynne-Edwards gave the “Group selection mechanics theory,” suggesting that the behaviors that improved group survival could evolve despite an individual disadvantage (Wynne-Edwards 1986). Hamilton proposed the theory of “Kin selection” (Hamilton 1970). The list does not end here; the wide interest among the researchers to understand the process of aging has led to many other theories which will be discussed later in this chapter.
Recalled Childhood Separation Anxiety Differs by Anal Sex Role among Gay Men
Published in The Journal of Sex Research, 2022
Ashlyn Swift-Gallant, Lindsay A. Coome, D. Ashley Monks, Doug P. VanderLaan
Male same-sex sexual orientation is partially influenced by genes (Alanko et al., 2010; Bailey et al., 2000; Ganna et al., 2019; Kendler et al., 2000; Långström et al., 2010; Sanders et al., 2015) but also reduces reproduction (e.g., Coome et al., 2020; King et al., 2005; Schwartz et al., 2010; Vasey et al., 2014). The kin selection hypothesis has been proposed to explain this apparent paradox (Wilson, 1975). Namely, while direct reproductive potential is decreased, same-sex oriented males may pass on their genes via indirect means by increasing kin’s reproductive success. Support for this hypothesis has been garnered among androphilic males in some societies, such as among the Samoan fa’afafine and gay men from Indonesia (e.g., Nila et al., 2018; VanderLaan et al., 2017). These groups show an increase in willingness to allocate time and monetary resources to nieces and nephews compared with gynephilic males from these societies; however, this increase in kin-directed altruism was not found among Western and Japanese gay men (reviewed in Vasey & VanderLaan, 2014).
The Selfishness Questionnaire: Egocentric, Adaptive, and Pathological Forms of Selfishness
Published in Journal of Personality Assessment, 2019
One variant, adaptive selfishness, is defined as a “softer” form of selfish behavior with an eye to others, and is hypothesized to be the least pathological variant, with a basis in evolutionary theory and social psychology. Unlike other forms, those displaying this variant care not just for themselves, but also for their family, and at times their friends. Some selfish behaviors could be justified on the grounds that others benefit from such selfishness, even to the extent that giving oneself priority in life can benefit others. Particularly at an evolutionary level, ensuring one's well-being and survival can be driven by the overriding need to look after one's family and promote genetic fitness (Dawkins, 2006). For example, if it came down to taking the last place in a lifeboat in preference to a child, or killing another person to avoid being killed, adaptively selfish people would act affirmatively to ensure that their own family would not suffer from their absence. Kin selection theory emphasizes the importance of the individual looking after the interests of family members who are closely genetically related (Hamilton, 1964). From a reciprocal altruism perspective (Dawkins, 2006), helping and caring for friends who can in turn help one in the future can be taken as a form of positive selfishness rather than giving selflessness. At a social level, telling white lies is arguably selfish as it benefits the teller by smoothing out social encounters at the cost of dishonestly (but beneficially) sparing the listener's feelings (Ariely, 2012). As this adaptive form of selfishness could be theorized as promoting “survival” both in the extreme and in less harmful social settings, it might be expected to be more prevalent than other forms of selfishness. Furthermore, because this form of selfishness is somewhat more socially positive (i.e., at times including benefits to others), we anticipate that it would be relatively more adaptive and functional. As such, adaptive selfishness was expected to be less associated with antisocial, narcissistic, and histrionic personality disorders, psychopathy, and Machiavellianism than other forms of selfishness.