More Catch Up
Aug. 24th, 2005 12:07 amHere's another catch-up essay called Automated World Building for RPG Games, posted to my
technaut journal.
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In mammals, birds, and many other species, sex is determined by the sex chromosomes, called X and Y in mammals, and Z and W in birds. For mammals, males typically have one of each (XY), while females typically have two X chromosomes (XX). All individuals have at least one X chromosome, the Y chromosome is generally shorter than the X chromosome with which it is paired, and is absent in some species, this pattern admitting some considerable variation. One interesting variation is in the platypus, a rather unusual mammal in many other ways, where sex is determined by 10 chromosomes. Males are XYXYXYXYXY and females XXXXXXXXXX. In birds, males have two of the same kind of sex chromosome (ZZ) and females have one of each type (ZW). In other species, including crocodiles, and most insects, sex may be determined by various other sex-determination systems, including those controlled by environmental factors such as temperature. Yet other species change sex during their lifetime.