‘No man is an island, entire of itself.’—John Donne, 1624
I have it on good authority that when the family of Og, the caveman, came down with pertussis and he did not, he gave as a reason that he had contracted the whooping cough when he was a baby Neanderthal.
In my youth, it was customary to bed healthy children with siblings who had measles or German measles in order to infect and care for them all at the same time, thereby obtaining protection for