Bees understand the concept of nothingness

It took humans millions of years of evolution and thousands of years of study to turn nothing into something. Ancient civilizations had various number systems, but it wasn’t until the seventh century AD that absence gained a presence in the Indian-origin numerical scheme we use today, becoming the mathematical concept “zero,” initially represented by a dot.

Bees, it seems, are able to grasp this abstraction, too. And increasingly it appears that other creatures get the difficult notion of nothingness as well.

A new study published in Science (paywall) by an international research team shows that bees understand that nothing is less than something—a concept once thought to be comprehensible only to humans. With this finding, the bees join an elite group of abstract mathematical thinkers, which includes people, parrots, and monkeys, who all have been shown to understand the idea of an “empty set.”

“Because bees with a miniature brain can acquire the ability to understand the concept of zero as part of a number sequence, it gives us important insights into how larger brains process numbers; and how we may have developed the use of zero for technology,” corresponding author Adrian Dyer of RMIT University in Melbourne, Australia tells Quartz.

For a long time, scientists assumed that, due to its complexity, the concept of the numerical quantity “nothing” was beyond the reach of any animal. Zero is, after all, the strange placeholder between positive and negative numbers, and the cornerstone of calculus. Even after its introduction in the seventh century, many humans rejected the valueless number, and it wasn’t until the 13th-century endorsement of the Italian mathematician Leonardo Pisano—better known by his nickname Fibonacci—that the Roman Empire accepted the concept.

Since then, humans have flattered themselves, thinking zero is too difficult for anyone else. “The number zero is central to contemporary mathematics and to our scientifically and technologically advanced culture. Yet, it is a difficult number to understand,” the researchers write. “Children grasp the symbolic number zero long after they start to understand, at around the age of 4 years, that ‘nothing’ can be a numerical quantity—’the empty set’ that is smaller than one.”

Recent studies on cognitively advanced vertebrates such as monkeys and birds challenge the assumption that nothing is too much for animals to understand. Bees are the first insects to prove they get it, too. This “suggests that such an understanding has evolved independently in distantly related species that deal with complexity in their environments, and that it may be more widespread than previously appreciated,” write the scientists.

To test this ability, the researchers had to first train bees on the concepts of “greater than” or “less than.” They did this by luring 10 free-flying bees from maintained hives, attracting them to various screens that showed different numbers of elements from one to four. Some bees were trained in the concept of “less than” by receiving a reward when fewer elements were shown on the screen and others got the opposite treatment, meaning they received a sweet nectar when more elements were present.

Soon, the bees had to choose between multiple data sets, with more or fewer elements, and were rewarded when they landed on the one showing the concept they were trained in—either “less than” or “greater than.” This shows bees can make the critical distinction, and it taught the bees to make rules.

Then the researchers displayed screens with no elements at all, among the numbered elements. The bees who were trained in the concept of “less than” wisely chose nothing over something. “Bees could […] extrapolate the concept of less than to order zero numerosity at the lower end of the numerical continuum,” the researchers explain.

In other words, honey bees can not only rank numerical quantities according to the rules “greater than” and “less than” but they can also take “less-than” to its logical conclusion. They make a rule based on their understanding of quantities and identify that empty sets fall below the number one in the order of numbers.

That said, bees found it easier to distinguish when the differences between quantities were greater. That is to say, they tended to be more accurate when choosing between zero and two, three, or four elements than when comparing just one element to none.

Still, this work does indicate bees can grasp a complex numerical abstraction, though their brains are very different from humans’ with far fewer neurons. Our last common ancestor was “a humble creature that barely had a brain at all [and] lived more than 600 million years ago,” the researchers explain. “But such differences do not prevent bees from knowing how to understand numbers, including zero.”

Based on studies examining animals in their ecological environments, numerical competence is a practical tool for creatures as well as people. It enhances their ability to reproduce, navigate, exploit food sources, hunt prey, avoid predation, and engage in social interactions, the scientists say. They believe that bees and the other animals who can conceptually grasp absence improve their chances of surviving and of passing on their genes. That means we do get something from nothing, after all.

Read next: A debate over plant consciousness is forcing us to confront the limitations of the human mind

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