No one knows exactly when the clones first appeared, but humans only became aware of them in the early 2000s. It was a German aquarium owner who first brought it to scientists’ attention. In 1995, he had acquired a bag of “Texas crayfish” from an American pet trader, only to find his tank inexplicably filling up with the creatures. They were all, it turns out, clones. Sometime, somewhere, the biological rule that making baby crayfish required a mama crayfish and papa crayfish was no longer inviolate. The eggs of the hobbyist’s all-female crayfish did not need to be fertilized. They simply grew into copies of their “mother”—in a process known as parthenogenesis. read more Disclaimer: Chances are that this post was requested by an advertiser.