Sexual bimaturism describes a difference in developmental timing between males and females of the same species. Sexual bimaturism can result in
sexual dimorphism
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
, but sexual dimorphism could also develop through differential rates of development. In many insects, the larval period of females is longer than that of males, and as a result of this extended growth period, these female insects are larger than their male conspecifics.
Male
simian
The simians, anthropoids, or higher primates are an infraorder (Simiiformes ) of primates containing all animals traditionally called monkeys and apes. More precisely, they consist of the parvorders New World monkey, Platyrrhini (New World mon ...
primates are generally larger than females of the same species due in part to extended growth periods.
Gorillas
Gorillas are primarily herbivorous, terrestrial great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or five su ...
demonstrate a particularly high degree of sexual bimaturism.
Bimaturism can refer to developmental differences within a sex related to
secondary sex characteristics
A secondary sex characteristic is a physical characteristic of an organism that is related to or derived from its sex, but not directly part of its reproductive system. In humans, these characteristics typically start to appear during puberty ...
. For example, male
orangutans
Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus ' ...
reach sexual maturity around age 15 but undergo an additional period of development later in life before they exhibit cheek flanges. Flanged males are generally preferred by females so that unflanged males need different mating strategies to compete with flanged males.
The onset of this second developmental phase varies greatly and may be influenced by the proximity of other flanged males.
In humans, sexual bimaturism is evident in that males begin
puberty
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testicles i ...
later than females. This may be related to selection for later maturation in males in a polygynous mating system.
References
{{Reflist
Human sexuality