Dassanech people in the Lower Omo Valley, South West Ethiopia. Loryra, South Omo, Ethiopia, January 2008. (Photo by Brent Stirton/Discovery Communications)

Armed Karo herdsman just back from protecting their cattle herds come down to the river to wash decorative clay markings off their bodies at the end of the day in the Omo Valley, South West Ethiopia. Dus, Omo Valley, Ethiopia, January 2008. (Photo by Brent Stirton/Discovery Communications)

Karo people in the Omo Valley, South West Ethiopia. Dus, Omo Valley, Ethiopia, January 2008. (Photo by Brent Stirton/Discovery Communications)

An image of a Hamar herdsman in the Omo Valley, South West Ethiopia. Dus, Omo Valley, Ethiopia, January 2008. (Photo by Brent Stirton/Discovery Communications)

An image of Karo maidens in the Omo Valley, South West Ethiopia.Dus, Omo Valley, Ethiopia, January 2008. (Photo by Brent Stirton/Discovery Communications)

Hamar people in the Omo Valley, South West Ethiopia. Turmi, Omo Valley, Ethiopia, January 2008. (Photo by Brent Stirton/Discovery Communications)

Karo people in the Omo Valley, South West Ethiopia. Dus, Omo Valley, Ethiopia, January 2008. (Photo by Brent Stirton/Discovery Communications)