Tag Archives: Flint

Human ancestors used fire to make stone tools 300,000 years ago

Stone blades found in the Qesem cave in Israel. Credit: Filipe Natalio.

Early hominins not only mastered fire, but they also employed it to thermally treat stone tools in order to fashion sophisticated flaked blades. That’s according to recent findings reported by researchers affiliated with the Weizmann Institute of Science in Israel, following excavations at the Qesem Cave, in Central Israel, dated to between 420,000 and 200,000 years ago.

Qesem Cave is believed to have been occupied by both humans and our extinct relatives throughout the Lower Paleolithic, leaving behind a wealth of stone tools and other artifacts. Most of these tools were made of flint, a material that is widely abundant in the area.

These ancestors would fashion their tools by employing a technique called knapping, which involved using another rock or tool to chip off smaller pieces from the flint, honing a sharp edge. But, sometimes, the tool making process didn’t end there.

Rocks as a thermometer time capsules

Credit: Avraham Gopher.

Researchers led by Filipe Natalio of Weizmann’s Scientific Archaeology Unit analyzed two types of flint tools that seemed to have been exposed to fire in the cave. Were these tools burned intentionally or by accident? That would be extremely challenging if not impossible to determine using conventional, visual observations. To get to the bottom of things, the team combined spectroscopy and machine learning with remarkable results.

“Our approach goes beyond the visual and subjective analysis. It relies on chemical modification in the rock structure that remains for a long period of time, based on thermodynamic considerations. So the rocks act as a thermometer. Using artificial intelligence, we can pick up that signal and estimate the temperatures be it higher or lower,” Natalio told ZME Science in an e-mail.

According to the findings published in Nature Human Behaviour, stone blades were heated to a lower temperature (259°C) than flakes (413°C), while pot lids from the same cave were exposed to an even higher temperature (447°C).

According to Natalio, heating the tools at a wide range of temperatures enabled early hunter-gatherers at the Levantine site to manufacture sharper and longer blades that were more efficient for butchering small game.

a pot lid, flake, and blade (not to scale). Credit: A. Agam.

“By the way, this technology only re-emerged during Middle Paleolithic, many thousand years later. They were pioneers of this technology,” the scientist added.

“Our approach provides a scientific mathematically well defined probabilistic approach to explain a probabilistic event of human behavior. This is one of the major and most exciting outcomes.”

The innovative approach employed by the researchers in Israel is versatile, enabling archaeologists to distinguish between intentional and contextual use of fire at a site. The most notable contribution of the study is the use of machine learning. “Nobody has done this so far,” Natalio told me.

In experiments meant to replicate similar thermal conditions, the researchers found that controlling the temperature of the heat-exposed flint improved blade production.

This also showed that the burnt flint tools were very likely exposed to fire intentionally.

“We do see clear differences in the estimated temperatures between different types of tools. A normal open fire would reach 600-700°C. Direct exposure of the raw material would shatter the flint, making it not useful for stone tool fabrication. So, they had to control fire together with understanding the properties of the raw material. And they were able to abstract thinking to plan in advance which procedure they would use for the fabricating a specific type of tool. There is where the intentionality comes in,” Natalio said.

This level of abstraction and complex behavior shows that early hominins were far more industrious and intelligent than previously thought.

“We can now understand that in the human lineage they were always pioneers of their time that made progress. These might not have been taken immediately, but their advances lived for long periods of time and made a difference to human evolution. The same happens today. If you feel that you are pioneering something and you are not understood, don’t give up!”

In the future, Natalio and colleagues plan on exploring other sites in the Levant and beyond in order to investigate how humans have been using fires across history. “This platform will allow us to explore many other exciting sites, be they older or younger,” he concluded. 

Small blade.

In the stone-age people recycled flint on purpose to produce precision blades

Research from Tel Aviv University (TAU) shows that recycling may, in fact, be an ancient tradition. Prehistoric humans deliberately “recycled” discarded or broken flint tools 400,000 years ago to create smaller, more specialized tools.

Small blade.

Tuber cutting with a small recycled flake, alongside a close-up.
Image credits Flavia Venditti / AFTAU.

In collaboration with members from the University of Rome, researchers from TAU’s Department of Archaeology and Ancient Near Eastern Cultures used two different spectrometry methods to analyze small, peculiar tools that have been uncovered at prehistoric sites throughout Europe and North Africa. Their edges show signs of use, the team reports, and were likely used for in food preparation. This theory is also supported by micro residue found embedded in the edges.

Recycling, before it was cool

“Recycling was a way of life for these people,” says Prof. Ran Barkai from TAU, the paper’s corresponding author. “It has long been a part of human evolution and culture. Now, for the first time, we are discovering the specific uses of the recycled ‘tool kit’ at Qesem Cave.”

The site of Qesem Cave is located just outside Tel Aviv. It was discovered during road construction projects which were undergoing in the area in 2000. Together with caves in Spain and North Africa and digs in Italy and Israel, Qesem produced the tiny blades the team analyzed in the study. Along with other material retrieved from these sites, the tiny blades show signs that prehistoric humans recycled broken tools, or those that were no longer needed, into tinier but more specialized blades.

Due to these cave’s microclimates, the flint tools were preserved in excellent condition, along with residue material from their use embedded in their edges — allowing for their proper analysis. The researchers used two techniques to do so: Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX).

“We used microscopic and chemical analyses to discover that these small and sharp recycled tools were specifically produced to process animal resources like meat, hide, fat and bones,” explains Dr. Flavia Venditti of the TAU and lead author of the study.

“We also found evidence of plant and tuber processing, which demonstrated that they were also part of the hominids’ diet and subsistence strategies.”

Signs of use were found on the outer edges, the team reports, indicative of cutting activity. Material on the blades suggests that they were used in activities related to the consumption of food: butchery activities and tuber, hide and bone processing.

The team went to great pains to meticulously analyze the tools to “demonstrate that [they] were used in tandem with other types of utensils,” according to Dr Venditti. This would suggest that the recycling was a deliberate process, used specifically to produce a more specialized tool to be used as part of a larger kit.

“The research also demonstrates that the Qesem inhabitants practiced various activities in different parts of the cave: The fireplace and the area surrounding it were eventually a central area of activity devoted to the consumption of the hunted animal and collected vegetal resources, while the so-called ‘shelf area’ was used to process animal and vegetal materials to obtain different by-products,” she adds.

The study touches on two hot topics in the field of stone-age archaeology, looking at both the role of small tools and that of recycling in prehistoric communities. The findings show that recycling was an established, on-going practice at Qesem Cave rather than a more opportunistic process. The people in this area had ample access to flint, the team also notes, so it wasn’t a question of scarcity. Rather, it seems that this group of people deliberately used tool recycling to produce these tiny blades because it was the most effective way to do so. The blades had to be tiny yet sharp, as they were used in tasks where “precision and accuracy were essential,” Venditti concludes

The paper “Recycling for a purpose in the late Lower Paleolithic Levant: Use-wear and residue analyses of small sharp flint items indicate a planned and integrated subsistence behavior at Qesem Cave (Israel)” has been published in the journal Journal of Human Evolution.

Flint water plant.

Flint’s water is deemed safe, Michigan Governor determined to end free bottled water service

Flint’s water is safe to drink again, say Michigan officials, adding that the state will soon cease the free bottled water service for locals.

Flint water plant.

Image via depositphotos.

Michigan Governor Rick Snyder issued a statement Friday saying tap water in Flint is safe to drink again, so bottled water is no longer necessary. Crews will distribute the remaining supply, at which point the PODS sites — which handle distribution — will all close.

“The scientific data now proves the water system is stable and the need for bottled water has ended,” the office of the Republican governor said in a statement.

“Since Flint’s water is now well within the standards set by the federal government, we will now focus even more of our efforts on continuing with the health, education and economic development assistance needed to help move Flint forward.”

Flint’s troubles with water began in April 2014, when it changed its source of drinking water from treated Detroit Water and Sewerage Department water (sourced from Lake Huron and the Detroit River) to the Flint River. Due to insufficient treatment and improper transport infrastructure, over 100,000 residents (between 6,000 and 12,000 of whom were children) were exposed to high levels of lead (a toxic heavy metal) in the drinking water.

After several studies showed the dangerous levels of lead in the city’s water, and the effects it had on the locals, a federal state of emergency was declared in January 2016. Flint residents were instructed to use only bottled or filtered water for drinking, cooking, cleaning, and bathing. The state began providing free bottled water to Flint residents in January 2016 after Snyder declared a state of emergency. Initially, water was distributed from nine PODS sites — one in each city council ward.

According to observations carried out by the Michigan Department of Environmental Quality between 2015 and 2017, however, water quality has now returned to acceptable levels — an overwhelming amount of the samples taken recently are within federal guidelines for lead and copper quantities.

Despite this, residents were instructed to keep using bottled or filtered water until all the city’s lead pipes had been replaced — which is currently scheduled for 2020.

So it’s easy to see why locals are, reportedly, hesitant to trust officials’ assurances — especially considering that the same administration was responsible for the water crisis in the first place. The city switched its supply from the Flint River back to Lake Huron back in 2015, but residents are still wary.

“Governor Snyder has failed to address the psychological trauma that his administration put the people of Flint through,” said Michigan State Representative Sheldon Neeley, who represents much of the majority-black city of 100,000. “The fact is, the people of Flint don’t trust the Snyder administration or the science they pay for — science that previously allowed our city to be poisoned.”

For better or worse, Governor Snyder is committed to ending the bottled-water handout program. The city, he says, should focus all funds on repairing and replacing its faulty water delivery systems.

Bottled water will continue to be distributed in Flint Community Schools buildings at least through the end of the current school year. The schools have a separate agreement with several leading beverage companies and retailers to supply water.