A team from the United States and France has found newly discovered hand axes from about 1.76 million year ago. The team made the discovery after traveling to an archaeological site located along the northwest shoreline of Kenya's Lake Turkana.
They've used a refined technique to date the dirt, and were therefore able to calculate the age of the tools.
Researchers have previously found two-faced blades and other large cutting tools that were excavated there. However, the new find is said to be older than similar stone-age artifacts in Ethiopia and Tanzania, which are estimated to be between 1.4 and 1.6 million years old.
The results of the new geological study are being reported in Thursday's issue of the journal Nature.
The study was led by Christopher Lepre of Rutgers University and Columbia University's Lamont-Doherty Earth Observatory.
If the researchers are indeed correct in their calculations, this could mean that ancient humans were already involved in refined tool-making, which requires high-level thinking, much earlier than thought.
The new found tools are said to have more distinct and planned designs, and differ greatly from the simple stone tools made from bashing rocks together.
"There's not a tremendous amount of diligence that goes into making the Oldowan tools, you can say they are kind of haphazardly made," Lepre told Fox News. "It's pretty simple in terms of the makers were bashing stones together to make sharp edges."
"I was taken aback when I realized that the geological data indicated it was the oldest Acheulean site in the world," Lepre told The New York Times.
The stone tools are known collectively as Acheulean tools. They are said to be the achievements of human ancestor Homo Erectus.
New York University anthropologist Christian Tryon told The Associated Press that the teardrop-shaped axes were "like a stone-age Leatherman or Swiss Army knife."
The axes are believed to have been appropriate for slaughtering animals or chopping wood. The thicker picks were used for digging holes.
What still remains a mystery to researchers is how the tools ended up leaving Africa.
Acheulean culture and its tools didn't arrive in Europe until about one million years ago, and it is believed that Homo Erectus colonized Europe over 1.5 million years ago.