|MadSci Network: General Biology|
Dear Rashad, Simply, a "male" is an organism that produces only sperm cells and a "female" is an organism that produces only eggs. Sperm cells have evolved to be donated; they are small and highly motile. Eggs are not meant to be donated. They have evolved to remain in a female's body until they are almost ready to hatch. In sexually reproducing organisms, the union of a sperm cell and an egg (fertilization) produces an embryo that develops into an offspring. A sperm cell alone cannot develop into an embryo. This has never been observed in any organism. But some female organisms (for example, certain microscopic animals called rotifers) can produce offspring from unfertilized eggs. That is called parthenogenesis. One definition of homosexuality in my dictionary is sexual activity with a member of one's own sex. So, a homosexual pair could be two males or two females. But a male, homosexual or not, cannot produce an embryo, because by definition he has neither eggs, nor the necessary organs to receive semen from another male and to support an embryo. On the other hand, a female, although she may be able to produce offspring parthenogenetically, cannot donate to or receive from another female genetic material because by definition she (or her female partner) has neither sperm, nor the necessary organs to donate anything. Therefore, in this sense, a more proper answer to your question is not that it is "impossible" to reproduce homosexually, but that a reproductive method that involves the exchange of genetic material between two individuals of the same sex has not evolved. Aydin Írstan
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