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Monkeys Have Been Using Tools for 700 Years

Jane Goodall’s discovery of chimpanzee tool use in 1960 came as a shock to her contemporaries, who believed that our ability to make and wield instruments set us above other animals. Since that time, we’ve gradually learned that lots of animals, from birds to insects, make and use tools. Some of them have been at it for a long, long time: Archaeologists have found that Brazilian capuchin monkeys have been using hammers to crack nuts for at least 700 years. That makes their stone hammers and anvils the oldest non-human tools known outside of Africa, the researchers write in a report they published this week in the journal Current Biology.

Image credit: Michael Haslam/Primate Archaeology Project

The bearded capuchin (Sapajus libidinosus) is a nimble little monkey found in the forests of northeast Brazil. S. libidinosus is not a particularly picky eater, and will happily chow down on flowers, fruit, leaves, bugs, frogs, small mammals, and baby birds. But scientists are most interested in the monkey’s taste for cashews. For the love of cashews, the bearded capuchin has learned to wield a small stone like a hammer, smashing the nut’s tough shell open on an anvil-like large stone. The monkey will then leave the tools in a pile by the cashew tree for next time. Hammer, crack, eat, repeat.

Archaeologists suspected that the capuchins had been repeating for a long, long time. To find out just how long, they used hand trowels to excavate the soil under four popular modern-day nut-smashing sites. They didn’t have to look very far to find what they were looking for; digging just 0.7 meters (2.29 feet) down yielded 69 different cashew-smashing implements.

The tools were surprisingly easy to identify. They looked exactly like the same stones preferred by today’s monkeys, and many of the rocks were smudged with cashew resin (a fact confirmed by chemical testing). And just like today’s monkey tools, most of the unearthed hammers were made of hard, smooth quartzite, while the anvils were flat sandstone.

The dig had also unearthed little pieces of charcoal. By carbon dating those pieces, the team could estimate the age of the stones nearby. They found that the stones could be sorted into three time periods. The stones near the top had been used quite recently. Those in the second layer dated from about 1614–1958, and the bottom layer went all the way back to the year 1266.

Project leader Michael Haslam is an archaeologist at the University of Oxford. “This is an exciting, unexplored area of scientific study that may even tell us about the possible influence of monkeys' tool use on human behavior,” he said in a press statement. “It is possible that the first humans to arrive here learned about this unknown food through watching the monkeys and their primate cashew-processing industry.”

Studying monkey behavior has been quite a shift for Haslam, who’s spent most of his career looking at artifacts and remains. The live animals are a lot more unpredictable, he notes in the video above: “They have their own lives going on. Sometimes you’ll see them beginning to do something really interesting with their tools, and then another monkey comes running in and there’s a big fight, or they have to leave for some reason, or they just fall asleep.” 

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Big Questions
Why Do Cats Freak Out After Pooping?
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Cats often exhibit some very peculiar behavior, from getting into deadly combat situations with their own tail to pouncing on unsuspecting humans. Among their most curious habits: running from their litter box like a greyhound after moving their bowels. Are they running from their own fecal matter? Has waste elimination prompted a sense of euphoria?

Experts—if anyone is said to qualify as an expert in post-poop moods—aren’t exactly sure, but they’ve presented a number of entertaining theories. From a biological standpoint, some animal behaviorists suspect that a cat bolting after a deposit might stem from fears that a predator could track them based on the smell of their waste. But researchers are quick to note that they haven’t observed cats run from their BMs in the wild.

Biology also has a little bit to do with another theory, which postulates that cats used to getting their rear ends licked by their mother after defecating as kittens are showing off their independence by sprinting away, their butts having taken on self-cleaning properties in adulthood.

Not convinced? You might find another idea more plausible: Both humans and cats have a vagus nerve running from their brain stem. In both species, the nerve can be stimulated by defecation, leading to a pleasurable sensation and what some have labeled “poo-phoria,” or post-poop elation. In running, the cat may simply be working off excess energy brought on by stimulation of the nerve.

Less interesting is the notion that notoriously hygienic cats may simply want to shake off excess litter or fecal matter by running a 100-meter dash, or that a digestive problem has led to some discomfort they’re attempting to flee from. The fact is, so little research has been done in the field of pooping cat mania that there’s no universally accepted answer. Like so much of what makes cats tick, a definitive motivation will have to remain a mystery.

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Animals
Watch a School of Humpback Whales 'Fish' Using Nets Made of Bubbles 

Just like humans, humpback whales catch many fish at once by using nets—but instead of being woven from fibers, their nets are made of bubbles.

Unique to humpbacks, the behavior known as bubble-net feeding was recently captured in a dramatic drone video that was created by GoPro and spotted by Smithsonian. The footage features a school of whales swimming off Maskelyne Island in British Columbia, Canada, in pursuit of food. The whales dive down, and a large circle of bubbles forms on the water's surface. Then, the marine mammals burst into the air, like circus animals jumping through a ring, and appear to swallow their meal.

The video offers a phenomenal aerial view of the feeding whales, but it only captures part of the underwater ritual. It begins with the group's leader, who locates schools of fish and krill and homes in on them. Then, it spirals to the water's surface while expelling air from its blowhole. This action creates the bubble ring, which works like a net to contain the prey.

Another whale emits a loud "trumpeting feeding call," which may stun and frighten the fish into forming tighter schools. Then, the rest of the whales herd the fish upwards and burst forth from the water, their mouths open wide to receive the fruits of their labor.

Watch the intricate—and beautiful—feeding process below:

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