On this basis, zero tolerance of petty offences can send a powerful social signal about much more serious crimes.

"Laughter is an honest social signal because it's hard to fake," Professor Provine says.

Gender differences in response to physical and social signals involved in human mate selection: The importance of smell for women.

Or a social signal he didn't know?

Achieving social signals to input into its algorithms is well underway.

If females provide more social signals, males will develop more mature songs at a faster rate than other male birds.

Typical attachment development begins with unlearned infant reactions to social signals from caregivers.

Furthermore, the differences between the real grin and the crocodile version are obvious enough to be used as social signals.

"We come to conclusions about the social signals we're reading, and it's easy to overemphasize our ability to accurately perceive what others mean," she said.

It's all about sending out social signals.