"Sympathetic concern" has also been observed in gorillas, bonobos, dogs and even rooks - but it is the calming effect that it had on the Chester Zoo chimps which is said to be a new observation.

BBC: Hugging benefits fractious chimps

His books consist of a series of plainly stated statistical observations, in support of deceptively modest conclusions, and the evidence in support of his original observation is now so overwhelming that the Flynn effect has moved from theory to fact.

NEWYORKER: None of the Above