Insect behavior and the nervous system

Insects are the most diverse animal group on Earth.  They live in almost all the habitats the world has to offer, and have a fantastic range of behaviors.  They share all the senses we possess as humans (vision, taste, touch, smell, hearing), and some well beyond our reach. For instance, insects can see a quality of light invisible to us - this is called polarization.  Others can sense heat over many kilometers, and some might even be able to sense the earth’s magnetic field. 

Insects perform daily tasks similar to those of vertebrates (finding food and mates, raising offspring, communicating, navigating, migrating).  In order to do this, they must be fast learners with good memories (such as of their favorite flowers or preferred foraging places). Furthermore, insects can use the sun and sky to navigate their way back to their nest over thousands of kilometers. Some insect species, such as ants, have complex social structures and effectively communicate with one another.  All of these insect behaviors are controlled by their tiny nervous systems, which makes them a fascinating feat both to great scientists of the past such as Charles Darwin and to modern researchers.

Find the insect nervous system fascinating? Read more about it here.

Are bigger brains better?

The insect brain is tiny compared to the human brain.  Our brain has 10 times more working units, called neurons, than there are people living on this planet.  In contrast, an insect brain has about as many neurons as a medium sized city (between a hundred thousand and one million). Commonly, bigger brains are associated with being “better” (as indicated by the insult “pea-brained”). Just like a giant supercomputer is more powerful, and can achieve more complex processing than the chip in our mobile phones, we associate bigger brains with allowing animals to solve more complex problems, having more diverse behaviors, and being more flexible in their dealings with their surroundings. Yet insects are able to perform all these fantastic feats with their tiny brain.  This amazed Darwin nearly 150 years ago, and poses a distinct challenge to the bigger = better hypothesis.

One thing to consider when comparing the brains of different species is the size of the animal in question.  This is because brains scale with body size, and smaller animals need less brain power to control a smaller body. Insects might have tiny brains, but they also have tiny bodies. Thus, in comparison to their size, their brains aren’t particularly small. Moreover it is not just important how many processing units there are in total, but also the ways in which they are connected and how exactly they process information. A modern cellphone with its tiny chip is as powerful as supercomputers were 40 years ago because the way information is processed is much more efficient these days. This principle also applies to animal brains, and while relative brain size gives some indication of the power of a brain, much of its power might lie in the detailed composition of its neurons and how they process information. Currently, the best measure for a powerful brain is still heavily discussed and actively investigated by neuroscientists – so we will need to wait for future years to come for a full answer. One thing is for sure: don’t underestimate a tiny insect when it comes to brain power!

Read more on brain size and intelligence here. 

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