Further selection occurs due to the birth interval for a single female averaging 2–2.5 years. Male fitness would benefit from inseminating other females during a birth interval. This hypothesis is supported by the large scrotal size allowing for increased sperm production.
The selection of mates is influenced by the time between births for a female (2–2.5 years), and male fitness would be enhanced if they could inseminate other females during this period. This hypothesis is supported by the large scrotal size, which allows for greater sperm production.