Two scientists say a genetic study suggests the world's first
language may have used clicks.

Still found in parts of Africa, click languages rely on distinctive
clicking sounds made by the tongue to form words.

The US researchers say their study shows existing click
speakers are genetically diverse, meaning their languages
may be older than others.

Click languages are still found in the Hadza tribe of Tanzania
and the San groups of Botswana and Namibia.

Anthropological geneticists Alec Knight and Joanna Mountain,
and their colleagues at Stanford University, analyzed cells from
cheek swabs of several African populations for genetic markers.

They reasoned the more related click speakers are, the more
likely it is click languages arose relatively recently. If click
speakers are genetically diverse, it could imply other speakers
lost their clicks after diverging into separate populations.

They concluded the Hadza and San "are as genetically distant
from one another as two populations could be" and appear more similar to
non-click speaking groups than to one another.

The researchers are using the finding to dispute the current
theory that the San and Hadza languages arose independently, reports
inScight.

Not everyone agrees with the anthropologists' claim. Linguist
Bonny Sands, of Northern Arizona University, said: "Linguistically,
we don't think they are one group, and we don't believe they have
a common ancestor."