A team of researchers from Canada's University of Victoria and several American universities used modern forensic tools on ancient ones created over 250,000 years ago.
Animal residue they found on the tools may be the oldest animal protein residue ever found. It may also be some of the first direct evidence that our Stone Age ancestors were pretty wily. They could adapt to life even in a tricky environment with dangerous animals and harsh weather.
The tools were unearthed at an ancient oasis in Jordan between 2013 and 2015. Archeologists uncovered over 10,000 artifacts in what had been a kind of watering hole in the northeastern part of the country.
Twentieth-century development has lowered the water table in the marshes near Azraq, giving scientists better access to deeper sediment layers.
Researchers say the area was a kind of "paleolithic bus stop" between the African and Eurasian continents. A wide variety of animals went back and forth along the corridor for thousands of years, making it rich for exploration.
In examining thousands of flints, scrapers and ax heads, the scientists discovered that these Middle Pleistocene hominins didn't merely forage for food, they also hunted it. They butchered their meat. They protected themselves from becoming prey.
It also appears they liked variety in their diet. Residue found on these ancient tools shows the presence of duck, horse, camel, wild cow and even rhinoceros.
(PDF) lived thousands of years before the more modern Homo sapiens
first evolved in Africa. Researchers say their use of tools in this fashion suggests they were much more cognitively complex than some experts have thought.
How exactly does a little bit of horse on an ancient tool tell us they were smart?
"When we think generally about the story of human evolution, we see that we eat anything and everything to help us survive," said April Nowell, lead author of the study and a professor of anthropology
at the University of Victoria.
When the lab called to tell her that protein on one of the tools tested positive for horse, she was "over the moon" at the discovery.
Hunting with tools takes real planning, she said. It's not an activity done instinctively.
Dining in with dangerous animals at the next table wouldn't be a good idea. Carry-out took some doing in those days. These ancient peoples had to figure out when animals would be seasonably available. They'd have to plan their travel. They'd have to teach others how to make weapons and how to coordinate a hunt.
This animal residue is a rare clue as to what this mysterious hominin species was like. Bird bones don't often survive from this period, and no one has found hominin fossils in Jordan.
Having this protein puzzle piece, Nowell said, and "getting a window into this time period is incredible."