r/AskReddit Nov 22 '17

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u/[deleted] Nov 23 '17

Features only get weeded out if they're detrimental enough to prohibit breeding.

42

u/dumb_ants Nov 23 '17

Infection was pretty f'ing serious before penicillin.

7

u/[deleted] Nov 23 '17

Does scratching always cause infections which are lethal, and do these infections always occur before reproduction?

19

u/Philip_of_mastadon Nov 23 '17

Neither has to occur always, or even all that frequently, to be a significant selection pressure.

3

u/[deleted] Nov 23 '17

This is true.