For a long time now, the question as to why 99% of the world’s living organisms reproduce sexually has evaded scientists. Some answers are now coming to the front that previously existed only as ideas or theories. The problem with any concept with regards to this question was testing the concept or hypothesis.
It is very rare to find an animal, plant or organism that engages in both sexual and asexual reproduction. Strawberries do that, slugs, hydra, single cell organisms and water fleas are the most common species to reproduce in either manner.
What Is All The Hoopla About?
You see, reproduction is how organisms survive and a species flourishes in the face of new and ever present danger. If a species is not forced to evolve then it stagnates and eventually some new disease or condition kills it off. That is why species reproduce and make copies of themselves except they are not replicas.
When organisms reproduce asexually, clones or near identical babies are made. Sexual reproduction on the other hand brings together two individuals of a species and combines their genes for a third different individual with new genome structure. This is the basis for evolution and here’s why scientists think it is better.
A baby with genes from a mother and father naturally has properties of both. This kind of genetic variation preserves a species as a new threatening disease will never manage to wipe out an entire population owning to such differences. Those that survive then multiply and the gene responsible for protecting individuals from such a disease spreads through the entire population thus immunizing the population from any further outbreaks. It really is that simple.
Diseases Are Why Living Things Have Sex
The most popular theory is that diseases force living things to have sex. This theory however could not be tested until now. With the knowledge that water fleas reproduce asexually and sexually, their natural bacterial parasite was introduced with a batch of asexual offspring and another batch of sexual offspring.
While the sexual batch survived and eventually flourished, the asexual batch began to engage in sexual reproduction instead of continuing the asexual procedure and eventually defeated the bacterial parasite albeit taking much longer and risking the entire population. When under pressure, the water fleas upgraded to sexual reproduction. This soundly proves the thesis that diseases are why organisms began to evolve towards sexual reproduction. By the way, this evolution is also seen with parasites that need to adapt to continue flourishing on their new and improved hosts.
Today, this theory is known as the Red Queen Hypothesis taken from ‘Alice In Wonderland’. In order to stay safe in one spot you have to keep running. Something that our biology understands pretty well.