And, more importantly, which definition of the human genus is the right one?

Instead, we should define the human genus by looking at our evolutionary tree.

In 2001, one team of geneticists took an even broader approach to the human genus question.

He says our conventional picture of the dawn of the human genus needs a slight modification.

Wood says that, of the three, only H. erectus deserves a place in the human genus.

Chimpanzees belong in the human genus.

Many of the scientists who study human evolution would actually deny there is a problem defining the human genus.

It is things like the shape of our chin and our brow that define the human genus, he says.

So not only do chimpanzees deserve a place in the human genus, using this genetic definition gorillas should be included too.

But researchers like Schwartz argue that Linnaeus's decision may help explain why the human genus continues to be so difficult to define.

Wood says the human genus began when our ancestors finally turned their backs on the trees, and when childhoods began to lengthen.

In other words, it might be simply duration of existence -not anatomical features or behaviour -that defines the dawn of the human genus.

Chimpanzees belong in the human genus They found that the typical primate genus is between 11 and 7 million years old.