Chimpanzees pass down a ‘secret handshake’ through the generations,according to new study.Researchers found that troops of chimps pass on traditions,including the handshake,from one generation to the next and they differ from group to group.When chimps are cleaning,they adopt a ‘grooming handclasp’ two chimps clasp onto each other’s arms,raise them in the air and groom each other with their free hand.Previous research suggest this handclasp may be a cultural phenomenon-like how people greet each other-but only some chimpanzee colonies practise this grooming behaviour.Researchers looked at chimps on the chimfunshi wildlife orphanage Trust in Zambia-finding some prefer to clasp hands,while others clutch onto another chimp,s wrist.Mark Bodamer,of Gonzaga university,said:These observations support the conclusion that these chimpanzees socially learn their local tradition,and that this might be evidence of social culture.”