Counting by crows, spider silk sensors, & caterpillar's static electricity | Last Week in Science (26 May 2024)

Crows can count their calls

If I ask you to repeat a word five times then you will say that word five times because you can count. We don't know any other animal who can count the sounds it makes except us but in a recent study scientists have shown that crows can count their calls too.

Crows are intelligent birds that have the ability to recognise faces and even use objects as tools. They can also be trained to produce their characteristic 'caw' calls on cue. In a recent study, scientists used such trained crows who can be made to caw when asked to. They showed a number, between 1-4, on a screen that would be the number of calls they want the crow to make or said that number and the crow would be then asked to start their caw caw and touch a button when done. If the crows made the number of calls matched with the number on the screen then they got a seeds or worms as a reward. The scientists found that the crows learnt to produce the same number of calls which was shown to them. Their first call was different for different numbers that means they can count and even plan the number of calls that they will make.

Although, this counting by crows does not mean that they can understand numbers but studying this behaviour in birds can help us to understand how the human brain evolved to make sense of numbers. This understanding can help individuals who have difficulty in making numerical calculations called as dyscalculia.

Reference: These crows have counting skills previously only seen in people


Sensors inspired from spider silk

What could be the next advancement in wearable technology after wrist bands and rings that monitors your health? It is biosensors that can be directly printed on your skin and can be repaired or even washed away. There already exists biosensors that can be directly applied to the skin, but these interfere with the normal functioning of the skin. 

Taking inspiration from spider silk, researchers at Cambridge University have now created biosensors that can be spun into thin fibers. These fibers are 50 times smaller than human hair and can be printed directly onto surfaces like a fingertip or flower petal. They can be printed with such precision that they can match the shape and pattern of a fingerprint. These biosensors are also inexpensive and eco-friendly. Another advantage is that this biosensor does not interfere with the function of the skin, and the user does not feel that they have a biosensor present on their skin.

The biosensors can be used for monitoring our bodies and even the environment. They have the potential to take virtual reality experiences to the next level. These biosensors are in the process of commercialisation, and we hope to see them out in the market for use soon.

Reference: Imperceptible sensors made from ‘electronic spider silk’ can be printed directly on human skin

Static electricity to evade predators

Remember the static charge that can make a balloon stick to your hair or give you tiny shocks when you touch a metal surface? That same static electricity helps caterpillars protect themselves from predator wasps by detecting the frequency of their wing movements.

Scientists have known that insects build up static charges on their bodies, which can push or pull other charged objects in their environment. Researchers at the University of Bristol wanted to see if the static electric field from a wasp, which can move caterpillar hairs, could be detected by the caterpillar and alert them to the wasp's presence. They measured the static charge of both the caterpillars and the wasps. Then, they calculated and measured the electric field and the movement of caterpillar hairs in response to the wasp's static electric field. They found that the movement of a wasp's wings could indeed move the caterpillar hairs, thus making the caterpillars aware of the wasp's presence.

This study highlights that insects like caterpillars can be affected by the electrical fields created by human-made electronic equipment. Since identifying predators is crucial for the survival of insects, we are interfering with their lives in yet another way.

Reference: Caterpillars can detect their predators by the static electricity they emit

Edited by ChatGPT 4.o