"Darwin theorized that mankind (both male and female) evolved alongside each other over millions of years, both reproducing after their own kind before the ability to physically have sex evolved. They did this through "asexuality" ("without sexual desire or activity or lacking any apparent sex or sex organs"). Each of them split in half."

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One knew, of course, that it was not the red cape any more than it was the boots, the tights, the trunks, or the trademark "S" that gave Superman the ability to fly. That ability derived from the effects of the rays of our yellow sun on Superman's alien anatomy, which had evolved under the red sun of Krypton. And yet you had only to tie a towel around your shoulders to feel the strange vibratory pulse of flight stirring in the red sun of your heart.

— Michael Chabon