The close relatives who share 98 per cent of our DNA

It was David Attenborough who finally dispelled the myth about the aggressive nature of the gorilla when he was filmed rolling around the undergrowth with a mother and her playful offspring.

The greatest of the great apes are gentle, leaf-munching vegetarians who, by and large, will keep themselves to themselves unless they feel directly threatened - a far cry from the King Kong of cinema screens.

We humans may like to think of ourselves as set apart from the rest of the animal kingdom but when we look into the face of a great ape, such as a gorilla or a chimpanzee, we can see just how close we are to our nearest living relatives.

After all, we share more than 98 per cent of our DNA with the chimp.

We also shared a common ape ancestor with the chimpanzee about 5 or 6 million years ago; and we only have to go a few million years further back to meet the ancestor we shared with all the great apes, including the gorilla.

In fact, so similar are we in terms of our genes that the scientist Jared Diamond once called us the "third chimpanzee", the second chimpanzee being the pygmy species known as the bonobo, which enjoys a life of free love and operates a matriarchal social order.

The Oxford zoologist Richard Dawkins once described how near we are to the rest of the living great apes by using the analogy of physical distance.

He asked us to imagine a chain of people holding hands, with each individual in the chain representing a different generation.

It would start with a teenager holding her mother's left hand, with her mother's right hand being held by her grandmother, who in turn would hold her mother's hand.

This chain continues back into ancestral time until finally we come to the common ape ancestor.

The question Dawkins posed was this: how far do we have to go until we reach that common ancestor we once shared with present-day chimpanzees?

The answer is surprisingly little - we would have to go just 300 miles, which is about equal to the distance from London to Edinburgh.

That includes all the generations of Homo sapiens that have ever lived, all the other members of the human family such as Homo erectus and Homo habilis, and, finally, the common ape ancestor itself.

In evolutionary terms this transition is minute. If the entire 3.5 billion years of life on Earth is measured over a 24-hour period, the evolution of humans and the rest of the great apes takes place in just the few moments that pass before midnight strikes.

Another clock is ticking now. It is time that we began thinking even more seriously about the survival of the rest of our living relatives in the animal world.