Sexual Selection

Sexual selection was an idea proposed by Darwin and refers to the process in which males and females attempt to maximize their chances of reproductive success. Within a species there are certain characteristics that make individuals attractive to potential mates. An example of this is in peacocks, female peacocks are attracted to males with long brightly colored tails, even though this makes them easier to be spotted by predators. This characteristic then evolves within the species due to how males with this characteristic have a higher chance of reproductive success and their characteristics being passed on to surviving offspring.

There are 2 types of sexual selection. Intersexual selection takes place when males compete for the attention of a female. The female will play an active role in choosing her mate and will choose the mate with the best characteristics in order to produce the offspring with the best characteristics. The other type is Intrasexual selection. This takes place when males compete against each other and are rewarded with the female. The female plays a passive role in this.

An example of intrasexual selection is Short’s sperm competition. This suggests that males are motivated to ensure that their sperm is successful in fertilization and can compete against other males. This is essential due to how in some species the female will mate with a number of different males so the male with the best fertilizing sperm will win. In humans this has resulted in men evolving to release much larger amounts of sperm after ejaculation to help increase the likelihood of fertilization.

Harvey and May suggested that ethic differences in testicle size may reflect adaptive differences in mating strategies within different populations. Samples showed that Chinese mens testicles were approximately half the size Danish mens testicles. This means a chinese man will be at a disadvantage if the female mates with a numerous amount of males and will most likely