Early Humans in Israel Had a Special Reason to Recycle Their Stone Tools

Throughout the Homo line, early humans were making some of their tools from older tools, changing their usage. Why?

Ruth Schuster
Ruth Schuster
ecycled patinated flint tool from Revadim. The yellow-orange areas are the old patinated surfaces of the item, while the new minimal modifications created a new edge that expose the fresh color of the flint.
Recycled patinated flint tool from Revadim: yellow-orange areas are old patination, slight modification created the new edge, exposing flint's true colorCredit: Tel Aviv University
Ruth Schuster
Ruth Schuster

Half a million to 300,000 years ago, Israel was thronged by early humans. Today, the site of Revadim in southern-central Israel is the fief of kibbutzniks but there are whispers of pre-sapiens occupation in the area: not bones, but stone tools. And almost a fifth of these tools were the result of recycling.

It has already been demonstrated that hominins in the future Holy Land, and in Spain and Italy, were recycling – picking up tools manufactured and discarded eons before them, modifying them, and using them again.

Happenstance? No. “Their selection, collection and recycling were intentional, conscious, and carried out regularly by early humans during Lower Paleolithic times,” Bar Efrati, Prof. Ran Barkai of Tel Aviv University and colleagues contend in a new paper published in Scientific Reports.

Their work sheds new light on recycled stone tools: how they were used in their first lifetime and then in the second one; and why this might have been done. The team suspects the impetus for this behavior was not merely economic but perceptual as well.

The paper relates specifically to artifacts found at the open-air site of Revadim, though similar evidence has been found elsewhere in Israel and in Europe too. Recycling began hundreds of thousands of years ago and continued as long as stone tools remained in use – which means into the Iron Age. In fact, Barkai believes that recycling was a common practice throughout the Homo line.

Live, and live again

Stone tools can be distinguished from just-rocks by the naked eye: their shape is unnatural. But how can we tell that a flint was a recycled older tool? One sign is double patination.

A hominin makes a hand-ax, for instance. Over time, its edges become dulled and it gets abandoned. Then it would just sit there, as rocks do.

The prehistoric site of Revadim during excavationCredit: Tel Aviv University
Recycled patinated flint tools from RevadimCredit: Tel Aviv University

If it sat in the appropriate environmental and chemical conditions, over time it would become patinated: coated in a glossy mineral veneer.

Then, if another hominin came along and picked up the patinated tool and sharpened its ages or otherwise remodified it, the patina would be damaged. Eventually the tool would be abandoned a second time, such is life. And if left bereft under the appropriate conditions – it would become double-patinated.

Patina color and qualities differ based on the physical and chemical circumstances. The eye notices when an object has more than one level of patination by differences in color, gloss and texture.

The uses made of the original and recycled tools are less obvious, and the team notes that at Revadim, tool recycling was significant in scope, alongside the manufacture of new tools from virgin rocks. About one fifth (18 percent) of the tools were recycled, with the rest created from scratch.

One is curious as to which hominins occupied Revadim half a million to 300,000 years ago. Based on tool-sets found in that and other Israeli sites from half a million years ago, they may have been a type of Homo erectus – though tools more advanced than erectus’ stone ax from that same time have been found.

It could mean that the hominins 500,000 years ago were a type more advanced than erectus, or that erectus by then had more advanced capabilities than has been assumed. But while fun to mull, the identity of the species isn’t pertinent to this paper.

Prof. Ran Barkai (left) and Bar EfratiCredit: Tel Aviv University

Why wouldn’t a hominin just pick up an old tool and reuse it? Why modify it again? Because its old edge would have been dulled, Barkai explains. Recycled tools typically feature old “active” edges that became blunted, and sharp edges that appear freshly chipped and differ in color from the patinated surface.

New life, new use

Did the tools serve the same purpose in their first and second life cycles? They did not.

The team tested 49 patinated old tools likely accrued during discrete occupation events at Revadim, which served as “blanks” to create new tools. Use-wear analysis of the edges was possible for 28 of them, mostly regarding the second use.

Deducing the tools’ use in their first incarnation was trickier, not least because sometimes the new modifications compromised the old surface.

Eight tools had enough gook on them from yore to produce use-wear results on both their old and new edges.

Close-ups of the new active edge of four flint tools from Revadim. One sees the differences in colors and texture between the new modified edges and the outer patinated, old, surfaces.Credit: Tel Aviv University

In their first life cycle, the tools were used mainly to cut soft tissues (meat and fat), Barkai says. The second time around, cutting tools had been reshaped into curvaceous scrapers, the better to process animal hides and bones.

“This may be due to the fact that in the second stage it was more difficult to produce a sharp edge for cutting and easier to produce a relatively thick edge in favor of scraping, but I do not know,” he says.

In the case of a chopper, it had been used to chop the first time around and was still used to chop in its second lifetime, the team writes. In other words, it retained its core function: to shatter bones, likely to get at the nutritious marrow.

A gift from the ancestors

Why might hominins predating the advent of modern humans have recycled tools?

Recycled patinated flint tool from Revadim: Shape and colors of the original item are almost fully preservedCredit: Tel Aviv University

No question, patinated rocks catch the eye. Also, they would presumably pick up any rock, used or “new,” that matched whatever they had in mind at that time.

But Barkai and the team believe there may be much more to the story. He has long suspected that archaic humans recognized the tools as an artifact from their past and wished to preserve it, to preserve its biographies, and “to serve as an item of memory to a site occupied throughout time,” as the team writes.

Note that among the recycled tools were freshly made ones. Making brand-new items was not a problem. But the researchers gained the impression that the manufacturers endeavored to preserve the old edges as much as possible, suggesting they were actively choosing to preserve these features insofar as feasible while still gaining new functional potential.

“In our opinion, the notably minimal reshaping of the new edges strongly suggests that their collectors chose to preserve the original appearance of the items as much as possible, while still providing them with new functional potential,” the team writes.

Recycled patinated flint tool from Revadim: yellow-orange areas are old patination, slight modification created the new edge, exposing flint's true colorCredit: Tel Aviv University

One wonders if the early humans didn’t pick up old tools because it’s easier to shape them into new tools, compared with virgin rock. The team notes that many advocate for a “least-cost, least-effort” rationale, but they don’t think that making a new tool from an old one is easier – especially if one is endeavoring to preserve its original appearance.

What they suspect is that mnemonic significance may be at play. The early humans may have regarded these tools, which were ancient when they were born, as “gifts of the ancestors,” Barkai suggests. Or maybe they evoked private memories.

One of the scrapers, for instance, had not two life cycles but three, yet much of its original patination can still be observed. “Its past connotations were chosen to be preserved during its next life cycle. In this way, the item’s previous roles, uses, and meanings were kept as a memory while new roles, uses, meanings, and mnemonic values were added,” the authors write.

Monkey see, monkey do again

They even postulate that early humans kept coming back to Revadim precisely to find old artifacts that they could reuse – and note that if our ancestors did so, they were in good albeit hairy company.

Chimpanzees and Japanese macaques, aka snow monkeys, habitually return to places where they had used and cached stones, and seem to purposefully choose and use the same stones.

Snow monkeys bathe in the hot spring of Jigokudani Monkey Park, JapanCredit: Hiro Komae / ASSOCIATED PRESS

Why? We do not know. But a chimp will throw a rock at a tree and then get that rock and throw it again, at the same tree, the authors point out. Why? We do not know.

But in the case of the late Acheulean toolmakers of Revadim, Barkai believes they deliberately collected antique tools, carefully preserved as much of their patinated surfaces as possible, and did so in appreciation of their ancestor who had once lived there and made the tool – and/or they cherished the site itself.

To them, the stone tool may not have been an inanimate passive object to be exploited until dulled and thrown away, Barkai and the team posit; it may have been imbued with agency, perceived as a sort of object-person with intrinsic value.

Half a million to 300,000 years after the event, it’s hard to say. We are a different species, surely more advanced than the early humans of Revadim, but our eye is still caught by shiny rocks. And perhaps when we tout our capacity for honoring our ancestors and their way of life, we may not have come as far as we think we have.

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