From Trevor Snell
Your article on whether our brain is encoded from birth to make infants pop everything into their mouths was thought-provoking (5 April, p 19). There must be an evolutionary benefit that overrides the risk of choking on the small parts. Perhaps the choking hazard itself isn’t important, but the grubby hands of the sibling or slobber from the pet dog is. The infant is ingesting microbes to colonise their gut. Yes, it’s that old hygiene hypothesis again!
Salisbury, Wiltshire, UK
