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HONEYBEES LEARN THE CONCEPT OF ZERO
Zero is a tricky concept.
Modern children eventually learn the symbolic number zero, but not until long after they have learned the more basic concept of an empty set. Humanity in general did not quite grasp zero until the rest of mathematics was well advanced. By some accounts that happened fewer than 1,500 years ago in India. Even the famously clever Ancient Greeks were baffled by the notion of a number for nothing, and muddled on without it.
But if you spend a few hours with some honeybees and some cleverly designed experiments, new research shows the bees will learn how to recognize zero and use it to a high degree of confidence. The discovery solidifies the bees’ reputation as one of the smartest insects, and it offers new insights into how numbers are processed by brains, both in the smarter animals like birds, monkeys, and bees, and also in human beings.
“The representation of abstract numerical quantities is demanding, but conceiving of ‘nothing’ as a quantity is even more challenging for the brain. After all, brains have evolved to process stimuli, which represent ‘something.’ Without light, a visual neuron does not signal optic information; without sound, an auditory neuron carries no acoustic information,” writes Andreas Nieder of the University of Tubingen, in an accompanying commentary to the new paper in the journal Science.
“The findings are all the more exciting when considering the phylogenetic remoteness of insects and vertebrates,” he wrote. “Their last common ancestor, a humble creature that barely had a brain at all, lived more than 600 million years ago, an eternity in evolutionary terms.”
To investigate their facility with numbers, the bees were trained first to recognize relationships of “greater than” or “less than,” said lead author Scarlett Howard, a PhD candidate and expert on honeybee cognition at RMIT University in Australia.
In the first stage, they were presented with pairs of white squares, each with
THE PRESSURE OF EVOLUTION HAS CAUSED MANY ANIMALS ... TO HAVE A SKILL LIKE THIS.
a different number of black spots. With sugar water as the prize, and a bitter drink they dislike as the alternative, some bees were trained to always choose the lower number. Others were trained to always choose the higher.
This was a relatively simple training regime because bees will always return to a place where they have found nutrition, Howard said, and because they never become full, but rather keep eating in service of the hive.
“We can work with them for hours at a time,” she said.
Once the researchers had built this honeybee skill up to greater than 80 per cent accuracy, they tested them again, without reward or punishment, with two options: a familiar number, and an empty set, represented by a blank white paper.
“What we found was that the bees trained to ‘less than’ would more frequently prefer to choose the empty set, even though they’d never seen it before, rather than a set with numbers in it. So that’s how we were able to find out the first level of their understanding of zero, and then we did other experiments to build on that to see at what level they were able to process zero and understand the concept,” Howard said.
In effect, the bees had grasped zero as more than just the absence of an input, but as an input in its own right, a number just like any other, one less than one.
There was a parallel experiment with similar results for the bees who were trained for “greater than.”
Similarly, when the bees were shown the number five, which they had not seen before, they were also able to tell whether it was greater or less than another.
A key interest in this work is how the cognitive basis for such a skill could have evolved.
“For example, it could be quite widespread,” Howard said. “The pressure of evolution has caused many animals that deal with complexity in their environment to have a skill like this. Or something else that is possible is that we already know from multiple other studies that bees are incredible learners, and they’re able to learn a number of things like concepts and rules and extrapolate them to new situations.
“This is perhaps why they’re able to learn the number rule and apply it to zero. It might not be that it’s necessary for their environment. It might be that because learning the shape, the scent, the colour and the position of different flowers in such a short lifespan that they have is so incredibly important for their survival, they’ve just become really good at being visual learners.”
“At the moment we don’t know the answer to this question,” she said.