Sperm: The Evidence for Evolution?


“This is the first clear evidence that suggests our ability to produce sperm is very ancient, probably originating at the dawn of animal evolution 600 million years ago,” said Eugene Xu, assistant professor of obstetrics and gynecology at Feinberg. “This finding suggests that all animal sperm production likely comes from a common prototype.”

This week’s journal Nature Research Highlight section features an article originally published in PNAS that demonstrates that some species of promiscuous hermaphroditic flatworms have “a variety of sperm shapes”. The ejaculate containing sperms are sucked by these worms after sex and only those sperms that have “pair of long bristles emerging at the mid-point and a tail resembling a paint brush” can anchor themselves in “the female orifice after copulation, preventing the sperm from being sucked out.” This is one example of adaptive evolution in these worms to select for those sperms that can quickly implant themselves in the female reproductive system such that they have higher chances to produce a zygote.
Figure obtained from Nature

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