- It is a well known fact that the main reason why testes in humans and most of the animals descend is to regulate the temperature of testes
- The functionality of sperms in temperature more than or equal to body is greatly reduced, the efficiency of sperms is so drastically reduced that artificial heating of testes is also been researched as a possible contraceptive methods
- Testes usually descend in the 7th - 8th month of gestation period due to the major influence of androgens (T) in the fetus, the condition in which the testes do not descend is known as "Cryptorchidism" which majorly affects the fertility of an individual

But, this behavior is not observed in mammals such as elephants, dolphins and whales
The case of aquatic mammals can be possibly ignored due to the fact that they live underwater hence they don't have to care much about the temperature regulation of their testes but what about elephants (https://www.publish.csiro.au/rd/pdf/srb03ab59)

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