What If There Were More Than Two Sexes?
Omkar singh,Main Writer ScienceRelief
Life would be: Easier. Or more complicated. It really depends on how you look at it.
The need for a third sex cell and therefore a third body type in order to produce offspring (and inspire a third restroom symbol) has never evolved on Earth. Such an arrangement would be inefficient and biologically costly. But nature does have multiple examples of more than two "mating types" within a species; clam shrimp have a male as well as two varieties of hermaphrodite, which either self-fertilize or mate with males but cannot mate with each other.
Not be outdone, the protozoan Tetrahymena thermophila has seven distinct "sexes" that can hook up and swap genes .
The stark male/female split in many organisms has long puzzled biologists. After all, having three mating types – wherein individuals can mate with the two types other than its own – boosts the odds of scoring a compatible partner from one in two to two in three, or from 50 percent to 67 percent; and the more varieties, the higher the odds. For stationary creatures, where finding a mate is difficult, multiple mating types have the advantage, said Laurence Hurst, a professor of evolutionary genetics at the University of Bath. For example, mushrooms have more than 30,000 mating types, Hurst told Life's Little Mysteries.
As for us mobile, social humans, finding a partner is not so tough (supposedly). Having three or more "genders," then, any two of which could make viable offspring (naturally), might be a reproductive blessing, but it could also be a relationship curse .
During the new DC Comics Universe series "Flashpoint," in which a time-traveling supervillain alters the past to warp the present, Life's Little Mysteries presents a 10-part series that examines what would happen if a major event in the history of the universe had gone just slightly different.
Part 4: What if ... there were more than two sexes?
In nearly all vertebrate species, sexual reproduction is binary – it involves male and female physical forms, each bearing a distinct sex cell ― a sperm or an egg, respectively.
The need for a third sex cell and therefore a third body type in order to produce offspring (and inspire a third restroom symbol) has never evolved on Earth. Such an arrangement would be inefficient and biologically costly. But nature does have multiple examples of more than two "mating types" within a species; clam shrimp have a male as well as two varieties of hermaphrodite, which either self-fertilize or mate with males but cannot mate with each other.
Not be outdone, the protozoan Tetrahymena thermophila has seven distinct "sexes" that can hook up and swap genes .
The stark male/female split in many organisms has long puzzled biologists. After all, having three mating types – wherein individuals can mate with the two types other than its own – boosts the odds of scoring a compatible partner from one in two to two in three, or from 50 percent to 67 percent; and the more varieties, the higher the odds. For stationary creatures, where finding a mate is difficult, multiple mating types have the advantage, said Laurence Hurst, a professor of evolutionary genetics at the University of Bath. For example, mushrooms have more than 30,000 mating types, Hurst told Life's Little Mysteries.
As for us mobile, social humans, finding a partner is not so tough (supposedly). Having three or more "genders," then, any two of which could make viable offspring (naturally), might be a reproductive blessing, but it could also be a relationship curse .
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Posted by Unknown
on Monday, January 07, 2013.
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