Honeybees can tell difference between odd & even numbers

Melbourne, May 4

A new study has shown that honeybees can learn odd and even number categorisation — also called parity classification. Till date this had never been shown in non-human animals.“Two, four, six, eight; bog in, don’t wait”. As children, we learn numbers can either be even or odd. And there are many ways to categorise numbers as even or odd.

Researchers associated with The Conversation have shown that honeybees can learn to order quantities, perform simple addition and subtraction, match symbols with quantities and relate size and number concepts.

To teach bees a parity task, scientists separated ‘individuals’ into two groups. One was trained to associate even numbers with sugar water and odd numbers with a bitter-tasting liquid (quinine). The other group was trained to associate odd numbers with sugar water, and even numbers with quinine

The scientists trained individual bees using comparisons of odd versus even numbers (with cards presenting 1-10 printed shapes) until they chose the correct answer with 80% accuracy

Remarkably, the respective groups learnt at different rates. The bees trained to associate odd numbers with sugar water learnt quicker. Their learning bias towards odd numbers was the opposite of humans, who categorise even numbers more quickly

We may memorise the rule that numbers ending in 1, 3, 5, 7, or 9 are odd while numbers ending in 0, 2, 4, 6, or 8 are even. Or we may divide a number by 2 — where any whole number outcome means the number is even, otherwise it must be odd.

Similarly, when dealing with real-world objects we can use pairing. If we have an unpaired element left over, that means the number of objects was odd. the conversation

Brain buzz

• Their brains are capable of parity categorisation
• Bees trained with sugar water learned quicker

The human angle

The studies suggest humans may have learned biases and/or innate biases regarding odd and even numbers, which may have arisen either through evolution, cultural transmission, or a combination of both. It isn’t obvious why parity might be important beyond its use in mathematics, so the origins of these biases remain unclear.

Simple or complex?

Researchers don’t yet know how the bees were able to perform the parity task. Explanations may include simple or complex processes. For example, the bees may have: -- paired elements to find an unpaired element -- performed division calculations - although division has not been previously demonstrated by bees -- counted each element and then applied the odd/even categorisation rule to the total quantity.

By teaching other animal species to discriminate between odd and even numbers, and perform other abstract mathematics, researchers can learn more about how maths and abstract thought emerged in humans.

Artificial neural network

• Artificial neural networks were one of the first learning algorithms developed for machine learning. Inspired by biological neurons, these networks are scalable & can tackle complex recognition and classification tasks using propositional logic.
• Researchers constructed a simple artificial neural network with just five neurons to perform a parity test. Network signals were given between 0 - 40 pulses, which it classified as either odd or even. Despite its simplicity, the neural network correctly categorised the pulse numbers as odd or even with 100% accuracy.
• This showed that in principle parity categorisation does not require a complex brain such as a human’s. However, this doesn’t mean bees and simple neural network used the same mechanism.

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