A new research suggests that our human ancestor’s made sophisticated stone tools about 1.76 million years ago but didn’t take the tools along with them to Africa.

A team of researchers 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 were able to calculate the age of the tools by using advanced technique.

The study was led by Christopher Lepre of Rutgers University and Columbia University's Lamont-Doherty Earth Observatory. The results of the new geological study are being reported in Thursday's issue of the journal Nature.

The newly found hand axes serves as the oldest examples of the Acheulean culture, 350,000 years older than any other complex tools yet discovered.

Anthropologists consider the Acheulean hand axes to be the culture of our ancestor Homo erectus, and we know H. erectus first evolved around 1.8 or 2 million years ago, study researcher Christopher Lepre, of Columbia University, told LiveScience. I think most researchers were anticipating that older stone axes would be found.

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 hand axes, carefully made of oval shape, are part of the Acheulian technology. Those tools are thought to have been made around 1.6 million years ago.

The ancient tools, typically large piece of stone with crudely-chipped edges, belonged to the earlier Oldowan toolkit. Lepre and his colleagues in the journal suggest that the hand axes found might have been made by H. erectus, and the Oldowan tools by the less cognitively-capable Homo habilis because H. erectus is often associated with Acheulian tools.

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 said in the published journal. 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 1 million years ago, and it is believed that Homo Erectus colonized Europe over 1.5 million years ago.