The Importance of Sex
Sex is important to life on Earth. It is not just Humans and the higher
animals that need sex. Whether species were created or evolved, or both or neither,
there are not many that have no form of sexual reproduction. Of course,
many species also can reproduce without sex, but the fact that they can
reproduce sexually is of great evolutionary significance. If a species
loses its ability to sexually reproduce, its ability to adapt is much
less.
Humans usually reproduce sexually. The great majority of Humans are
the result of purely sexual reproduction. Although on fairly rare
occasions Humans do reproduce asexually by binary fission, splitting
into two separate individuals this only accounts for a small percentage
of the Human population of the world.
It is also worth noting that quite often, even when asexual
reproduction occurs; it frequently follows on from sexual reproduction.
From the evolutionary point of view, sexual reproduction
is very necessary. Even relatively simple creatures like bacteria can
exchange genetic material and can adapt very quickly.
Imagine life on a planet that had no means of sexual reproduction. I would suggest that they would not have the ability
to evolve in the same way as life on Earth can.
Of course my suggestion that sexual reproduction is necessary
implies that species that have lost this ability and rely on asexual
reproduction only are at risk of being at an evolutionary dead end. For
example, a plant called the sour sob, Oxalis pes-capri, was
formed by a Chromosome mutation resulting in it being pentaploid. At
first this was believed to be an evolutionary dead end that was unable
to adapt further. Now a population of this highly successful plant has
been discovered that sets seed, so it is now reproducing sexually.
Another plant, Duckweed (Genus Lemna) normally reproduces only asexually
by budding into two genetically identical individuals. However, on rare
occasions this plant will flower and can change by recombination of
genes. In the evolutionary sense this is of great importance to the
plant.
