Theories and models in medicine
R. Paul Thompson, Ross E.G. Upshur in Philosophy of Medicine, 2017
Of course, things become more complicated when there are more alleles at the locus and even more complicated when more loci are added. Those complexities make an actual graphical representation difficult but the concept of a space within which the system at a specific time can be located is the same. Then laws of transformation must be specified. These specify how the system can change over time. In this case, there are two key classes of laws of transformation. The first specifies changes before reproduction, such as changes in the proportion of alleles due to one aspect of natural selection: deaths from predation, for example. The other specifies how the system changes through reproduction. The fitness of an organism determines reproductive success – another aspect of natural selection. Sexual selection – mate attraction and selection – belongs in this class of laws. We have constructed a theoretical model. If what the model predicts will happen over time matches observation and experimental results the theory is partially confirmed. Each successful prediction confers greater confirmation.
The biological bases of personality
Philip N. Murphy in The Routledge International Handbook of Psychobiology, 2018
Personality disorders can also be considered from an evolutionary perspective. Specifically, it has been argued that personality disorders provide important evolutionary benefits and are therefore under sexual selection, that is, they are maintained in the population due to the fitness advantages afforded by the disorder. It is important to emphasise that though those with personality disorders have a lower life expectancy (Fok et al., 2012), suggesting that these disorders are maladaptive, some disorders are associated with increased mating success (Sansone, Lam, & Wiederman, 2011). Hence, those with (at least some) personality disorders may achieve greater reproductive success. To investigate the evolutionary consequences of personality disorders, Vall et al. (2016) identified seven dimensions of personality pathology: negative emotionality, persistence-compulsivity, asociality, impulsive sensation-seeking, antagonism, subordination, and oddity. The researchers concluded that each of the seven dimensions investigated are under sexual selection. For example, impulsive sensation-seeking was associated with number of short-term mates, number of long-term mates, and upward mobility. These findings are consistent with the suggestion that personality disorders should be regarded as alternative ways of being rather than as illnesses, and proposals for revised classification systems (Brüne, Ghiassi, & Ribbert, 2010).
The Concept of Function
Lawrie Reznek in The Nature of Disease, 1987
Secondly, the Evaluative Theory cannot provide necessary conditions for having a function. To see this, it is necessary to understand that natural selection does not only lead to the evolution of traits that enhance the survival of the individual organism. Sexual selection can lead to the selection of traits that impair the survival chances of the individual, but which enhance the survival of such traits in the next generation. For example, the plumage of peacocks impairs the survival chances of each peacock, because it makes them more conspicuous to predators. However, the trait is selected because females find it attractive, and so males with the trait leave more offspring in the next generation.
Using an evolutionary perspective to understand the relationship between physical aggression and academic performance in late adolescents
Published in Journal of School Violence, 2019
José Antonio Muñoz Reyes, Rómulo Guerra, Pablo Polo, Eduardo Cavieres, Miguel Pita, Enrique Turiégano
The use of aggressiveness generates great social concern, since it affects humans along several aspects of their lives, but especially during adolescence (e.g., negative effects in life satisfaction for aggressors in Valois, Zullig, Huebner, & Drane, 2001; negative effects in quality of life for victims of bullying in Frisén & Bjarnelind, 2010; negative academic performance for aggressors; Loveland, Lounsbury, Welsh, & Buboltz, 2007; etc.). But in general, a broad perspective and explanation of the phenomena is missing. In this regard, evolutionary psychology offers a solid framework to address questions concerning human aggression. Within the evolutionary framework, aggressiveness is described as an adaptive strategy to solve contest competitions among individuals. When the competition is within-same sex individuals over the access to mates, aggression is related to sexual selection processes (Archer, 2009; Campbell, 2009; Puts, 2010). Sexual selection is a type of natural selection that causes the retention of traits (physical or psychological features) that increase the reproductive success of those individuals displaying them (Darwin, 1871). Sexual selection is usually divided in two mechanisms: intersexual selection in which individuals compete to attract or charm individuals of the opposite sex and intrasexual selection in which individuals compete to exclude rivals from mating and, therefore, monopolizing mating access themselves (Darwin, 1871).
Back to Stir It Up: Erectile Dysfunction in an Evolutionary, Developmental, and Clinical Perspective
Published in The Journal of Sex Research, 2019
Ylenia Nicolini, Antonella Tramacere, Stefano Parmigiani, Harold Dadomo
Cellerino and Jannini (2005) embraced a similar perspective. Considering that male reproduction is very sensitive to different kinds of stressors, they suggest that this fragility, together with the sensitivity of erection to internal (organic and psychological) and external (environmental) conditions, evolved as a specific fitness indicator under the force of evolution (Zahavi & Zahavi, 1997). According to Zahavi and Zahavi, sexual selection supports the existence of “honest” characteristics in the form of handicaps that impose individual high energetic costs and are carried only by males with high fitness. By mating with males possessing this costly characteristic, females are choosing a high-quality male that is determined by his ability to survive.
Men’s Sexual Interest in Feminine Trans Individuals across Cultures
Published in The Journal of Sex Research, 2022
Lanna J. Petterson, Paul L. Vasey
Research that addresses questions related to mate choice and sexual orientation may ultimately inform our understanding of sexual selection and the evolution of mating systems. For example, Semenyna et al. (2020, in press) has documented the routine occurrence of inter-sexual mate competition between cisgender women and feminine trans individuals for cisgender men in cultures such as Samoa and the Istmo region of southern Mexico. Like intra-sexual mate competition, this form of inter-sexual mate competition has the potential to influence cisgender women’s opportunities to engage in conceptive sex.
Related Knowledge Centers
- Sex
- Sexual Dimorphism
- Natural Selection
- Mate Choice
- Mating
- Reproductive Success
- Offspring
- Fitness
- Secondary Sex Characteristic
- Fisherian Runaway