title: Sexual selection and genital evolution: an overview.
abstract: BACKGROUND
  Genital morphology (especially male) among the animal kingdom is characterized by extensive differences that even members of closely related species with similar general morphology may have remarkably diverse genitalia.
  
  
  OBJECTIVE
  To present the sexual medicine specialist with a basic understanding of the current hypotheses on genital evolution with an emphasis on the sexual selection theories.
  
  
  METHODS
  A review of current literature on the theories of genital evolution.
  
  
  METHODS
  Analysis of the supporting evidence for the sexual selection theories of genital evolution.
  
  
  RESULTS
  Several theories have been proposed to explain genital evolution. Currently, the sexual selection theories are being considered to present valid and solid evidence explaining genital evolution. However, other theories, including sexual conflict, are still being investigated. All theories of genital evolution have their own weaknesses and strengths.
  
  
  CONCLUSIONS
  Given that many complex biological mechanisms, mostly unknown yet, are involved in the process of genital evolution, it is thus reasonable to conclude that not one theory can independently explain genital evolution. It is likely that these mechanisms may prove to have synergistic rather than exclusive effects.
authors.affiliation: Department of Andrology, Sexology and STDs, Cairo University, Cairo, Egypt.
authors.forename: Rany
authors.initials: R
authors.lastname: Shamloul
authors.forename: Ahmed
authors.initials: A
authors.lastname: el-Sakka
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Bella
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005260:Female; D005836:Genitalia, Female / Q000033:anatomy & histology*; D005837:Genitalia, Male / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D052586:Mating Preference, Animal; D012641:Selection, Genetic; D012727:Sex Characteristics; D013045:Species Specificity