Scientists say they have found evidence that a whale with a good idea can pass it on to other members of the group.

They report that the whales' knowledge is passed on in their genes to their descendants.

The findings are in the 27 November issue of Science magazine. This is the first evidence that cultural behaviour is passed on through the generations in this way in any species apart from humans.

And it says this ability of whales to communicate and socialize, using long-distance sonar, has probably helped their evolution and survival.

Close family links

A whale that thinks of a bright idea, like a better way of finding food or of defending itself against predators, can share the idea with other members of its group.

This is because many whales tend to live in closely knit groups of family members

The members of the group will have similar genes, because they are related to one another.

And the idea they receive from one member can help the entire group to survive better than other whale families.

The way the whales pass their knowledge on to their descendants is connected with their mitochondrial DNA (mtDNA).

The researchers looked at three whale species - sperm, killer and pilot whales - and found that genes in their mtDNA are similar in all groups of each species.

Communication has helped survival

Unlike the DNA that carries most of the map for the body, which is found in the nucleus of every cell, mtDNA is found only in the cell's protoplasm.

It is passed down virtually untouched from mother to calf, unaffected in any way by the father's genes.

But the mtDNA does not actually cause the inherited behaviour pattern. It simply rides along in the body of the whale that has the original idea and in its descendants.

Scientists call this phenomenon "molecular hitchhiking", and find that it mirrors the way knowledge and cultural behaviour are handed down.

Help from their environment

The report says: "Cultural traits learned, almost without error, from the mother or members of a matrilineal group are analogous to maternally-inherited mtDNA."

The report says whales have developed their advanced culture better than land-based species because of their environment.

The immensity of the oceans, for example, has allowed them to travel easily in permanent groups.