Scientists have discovered in Africa the world's oldest tool kit—crafted by early humans around 2.61 million years ago.
It includes the first known knives made by shearing sharp flakes of stone from larger rocks to cut meat and other resources, according to a Mirror UK report.
The technology suggests our primitive ancestors were much more intelligent than previously believed, the report says.
The tools were dug up at a site known as Bokol Dora 1 or BD 1 in the Afar region of north-eastern Ethiopia alongside animal bones of antelopes, prehistoric elephants, primitive hippos, crocodiles and fish.
The oldest fossilised jaw bone of early humans dating to about 2.78 million years ago was also found near the site five years ago.
A team has been working ever since to find out if there is a connection with the origins of systematic stone tool manufacture.
Geologist Professor Christopher Campisano, of Arizona State University in the US, saw the sharp-edged stone tools sticking out of the sediments on a steep, eroded slope.
He said: "At first we found several artifacts lying on the surface, but we didn't know what sediments they were coming from.
"But when I peered over the edge of a small cliff, I saw rocks sticking out from the mudstone face.
"I scaled up from the bottom using my rock hammer and found two nice stone tools starting to weather out."
The archaeological layer of animal bones and hundreds of small pieces of chipped stone unveiled after years of strenuous efforts represent the earliest evidence of early humans making and using stone knives.
The site records a wealth of information about how and when humans began to use stone tools.
Archaeologist Vera Aldeias, of the University of Algarve in Portugal, said: "Looking at the sediments under a microscope, we could see the site was exposed only for a very short time.
"These tools were dropped by early humans at the edge of a water source and then quickly buried," he was quoted as saying.
The animals found with these tools were similar to those found only a couple of miles away with the earliest Homo fossils.
Prof Kaye Reed, who studies the site's ecology at Arizona State, said: "The early humans that made these stone tools lived in a totally different habitat than 'Lucy' did."
'Lucy’ is the nickname for an older species of hominin known as Australopithecus afarensis, which was discovered at Hadar about 20 miles from BD 1.
Prof Reed said: "The habitat changed from one of shrubland with occasional trees and riverine forests to open grasslands with few trees. Even the fossil giraffes were eating grass!"