Elephants are attacking humans in revenge for years of abuse, scientists now believe.

The new research has given a chilling new meaning to the saying "elephants never forget".

It comes amid a growing number of reports in Africa of herds of elephants trampling through villages, apparently without cause or motivation.

New Scientist magazine said elephants may be harbouring a grudge against humans dating back to the age of poaching in the 1970s and 1980s.

This has created a generation of 'teenage delinquent' elephants hell bent on taking out their grievances on humans.

Joyce Poole, from the Amboseli Elephant Research Project in Kenya, said: "They are certainly intelligent enough and have good enough memories to take revenge.

"Wildlife managers may feel that it is easier to just shoot so-called 'problem' elephants than face people's wrath.

"So an elephant is shot without realising the possible consequences on the remaining family members and the very real possibility of stimulating a cycle of violence."

But other studies point to the fact young male elephants stay in musk far longer without the presence of bull elephants.

That may mean the young males remain aggressive far longer than is normal.

Scientists believe others may suffer from post-traumatic stress syndrome caused by losing a parent violently at a young age.

That again may manifest itself in violent behaviour later in their adult life.