The evolutionary history of testicular externalization and the origin of the scrotum

  title={The evolutionary history of testicular externalization and the origin of the scrotum},
  author={Karel Kleisner and Richard Ivell and Jaroslav Flegr},
  journal={Journal of Biosciences},
This paper re-examines the evolution of the scrotum and testicular descent in the context of the recent phylogeny of mammals. The adaptive significance of testicular descent and scrotality is briefly discussed. We mapped four character states reflecting the position of testes and presence of scrotum onto recent mammalian phylogeny. Our results are interpreted as follows: as to the presence of testicondy in Monotremata and most of Atlantogenata, which represent the basal group of all eutherians… 
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  • 2014
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The evolution of the scrotum and testicular descent in mammals: a phylogenetic view.
The scrotum may have evolved before the origin of mammals, in concert with the evolution of endothermy in the mammalian lineage, and that the scrotal has been lost in many groups because descensus in many respects is a costly process that will be lost in mammal lineages as soon as an alternative solution to the problem of the temperature sensitivity of spermatogenesis is available.
Anatomical evidence for the epididymis as the prime mover in the evolution of the scrotum.
  • J. Bedford
  • Biology
    The American journal of anatomy
  • 1978
The possibility is raised that the scrotal state may be linked to the sexual capacity of the male, in particular the ability to produce fertile ejaculates repeatedly within a limited period of time.
Zur Ursache des Hodenabstiegs (Descensus testiculorum) bei Säugetieren1
The hypothesis presented in this paper suggests a new adaptive explanation for the descent of the testes in mammals and regards its development as an example of evolutionary compromise.
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  • Biology
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  • 2007
Together all of the evidence indirectly supports the view that lifestyle factors in addition to other genetic and environmental influences could be contributing to the secular trend in declining male reproductive parameters.
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By dissection or from published descriptions mammals could be grouped into two broad categories according to their evolutionary development and testicular position; this was generally consistent with the initial hypothesis that the two phases of descent were completely different.
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The hypothesis that descended scrotal testicles in humans and many other mammals evolved to provide a situation specific means of activating sperm is advanced and the features of mammalian reproduction and behavior that are consistent with this hypothesis are explored.
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The evolution of the scrotum: a new hypothesis.
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    Journal of theoretical biology
  • 1990