London: A discovery of Stone Age tools, mainly either spear heads or scrapers, has revealed that migration from Africa to India and other Southeast Asian countries as well as Australia took place not 60,000 years ago, but 70,000 to 80,000 years ago - and perhaps even earlier.
Dr Michael Petraglia, of Oxford University, and colleagues say stone artefacts found in the Arabian Peninsula and India indicate that humans moved out of Africa much earlier than thought till now.
"Our evidence is stone tools that we can date," BBC News quoted Petraglia as saying.
"During the period we`re talking about, the environments were actually very hospitable. So where there are deserts today, there used to be lakes and rivers, and there was an abundance of plants and animals," he added.
This means it was more likely humans migrated by land than in boats, he said.
In particular, some tools were sandwiched in ash from the famous Toba eruption that geologists can date very accurately to 74,000 years ago.
However, previous research based on genetics shows that humans left Africa around 60,000 years ago or even more recently.
"These tools show that people were in these regions, but the genetic data show an exit from Africa of later than 60,000 years ago. The people in India could have died out," said Professor Chris Stringer, of the Natural History Museum in London.
According to Petraglia, however, all of the genetic studies were based on today`s people, and so may not be accurate.