Scientists claim to have uncovered the world's oldest stone tools. They were discovered on the banks of Lake Turkana in Kenya, and they date back 3.3 million years. They are 700,000 years older than any previous tools discovered, even predating the first Homo genus people. The find was made by a team led by Scott MacPherson of Curtin University in Australia. The tools were made from bits of rock with cutting edges shaped by human hands. They may have been used as knives or scrapers. The scientists say the artifacts show that our earliest ancestors had an advanced understanding of geology long before there were any modern humans around. Other experts say the tools could have been made by a different species of early man. They claim the technology and quality of workmanship of the instruments is not primitive but rather shows an advanced level of skill that can only be achieved through centuries of practice. Lake Turkana is a large alkaline lake in North-Eastern Kenya. It has been known for its high content of arsenic which makes it toxic to drink without treatment. The area is very arid with almost no rain between seasons, so all the water comes from the sky. It is possible that ancient man used these stones as weapons because they found food hard to come by and might have fought each other for territory or mates. Lake Turkana is one of the most important archaeological sites in Africa.