Why is there sex in this world?

Answer 1

Sex exists in a biological sense to create diversity and strength among an entire species. To explain, it is easier to contrast sexual reproduction with asexual reproduction. Asexual reproduction occurs when a single parent gives rise to an offspring with a genetic composition that replicates the parent. In such reproductions, all offspring are exact copies of their ancestors, and so there is no variation of characteristics among the population. In effect, the offspring are clones of the parents.

Asexual reproduction is very efficient - individuals do not have to seek out a mate to engage in fertilization, and the amount of energy and time expended in reproducing an identical copy is significantly less than for sexual reproduction. 1

There is a significant disadvantage to asexual reproduction - there is no diversity within the species. Should the population's environment change, even by a small amount, the change could prove lethal to the entire population. Should a new predator or disease come onto the scene, it could wipe out the entire population. Bacteria are an example of organisms that reproduce asexually. That is why, once a suitable antibiotic is identified, it will treat a bacterial infection by killing all individual bacteria that make up that population. There are no variations, and therefore an entire population is vulnerable to a single antibiotic treatment.

In sexual reproduction, a male and a female of the same species divide and then combine their genes, and by doing so, create a unique combination of genetic traits in their offspring. These unique genetic traits in turn give rise to distinct combinations of strength, agility, intelligence, shape, height, hair and eye color, etc., and also give rise to congenital variations, such as resistances to specific infections, susceptibility to certain illnesses, and so on. These variations create diversity among the population, and thereby create a more resilient population, since a single threat has a lower probability of wiping out an entire population compared to a population that reproduces asexually.

Sexual reproduction also enables a species to propagate only the most successful qualities in an individual, and to filter out less successful traits. This occurs through two ways. First, those individuals that are too weak or sick to reach the age of sexual maturity will never pass on their genes, thereby creating a built-in mechanism to weed out the least desirable genetic traits. Second, most species exhibit instinctive mating behavior - usually among the males - that includes some type of ritual, contest, or even combat in order to win the right to mate with a partner. These instinctive behaviors create a powerful means to ensure that only the strongest and most suitable individuals win the right to procreate, and thereby keep the entire population strong.

Sex, or sexual reproduction, therefore helps a species in two ways:

1. The sexual reproduction itself create greater diversity among a species, and therefore makes the species as a whole more resilient to environmental changes and threats; and
2. The instinctive mating rituals surrounding sexual reproduction serve to constantly strengthen the overall population in a given species.

1 Note that bacteria, and other asexually reproducing organisms, can mutate through reproduction, occasionally giving rise to variations in the species, but mutations that lead to viable organisms are rare and are aberrations to the reproduction process.

Answer 2

There are a number of reasons why human beings have sex. Sometimes, it's because the couple want to have a baby. Sometimes, it's a way for two people to show love and affection. And sometimes, people have a strong sexual desire and they decide to seek some pleasure.

Answer 3

Well, pregnancy is risky and giving birth can be very painful. So there has to be a really good reason to have sex!

Answer 4

so you can have babies