Last updated: 3 november, 2009 - 11:25 GMT

Lake Makgadikgadi

An ancient giant lake in the middle of the Kalahari desert, mysterious stone axes and years of research, all might give us clues about how early humans adapted to climate change.

Professor David Thomas with a giant stone axe head found in dried base of Lake Mkgudikgudi

The unwieldy giant stone artefacts puzzled Professor Thomas's team

Oxford University researchers in Botswana have discovered artefacts that explain how humans adapted to changes in their environment up to 150,000 years ago.

The discoveries took place around the now dried up Lake Makgadikgadi.

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Professor David Thomas is the Head of the University's School of Geography and Environment.

Network Africa's Akwasi Sarpong asked him to describe Lake Makgadikgadi now - and how it was in the distant past.

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