I think you're confused. There are only two sexes, male and female. Sex is what you were biologically born as from birth, while gender is what you choose to identify as. Gender is a choice, sex isn't. They couldn't discover any other genders because at the time they probably didn't even know what gender was like three thousand years ago, therefore they couldn't look like a different gender.
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The formula for specific gravity, given that the reference substance is water, is the density of the object divided by the density of the water.
Prokaryotic cells are cells without a nucleus and has simple parts free flowing in the cell. Some examples are Escherichia Coli Bacterium (E. coli). It is a rod-shaped bacterium commonly found in the lower intestine of warm-blooded organisms. And Streptococcus Bacterium. This prokaryote is responsible for strep throat. It is an infection of the back of the throat which includes the tonsils.