Why swarming locusts grow giant brains

Image via Wikipedia

One of my favorite blogs posted this recently. (If you do visit the original site – the comments are worth a scan too – who says geeks have no sense of humor?).  I did read though that a leap in the evolution of the human brain is attributed to the way we increasingly banded into groups.

At the risk of anthropomorphizing locusts, I can’t help but wonder what living in urban settings might be doing to our brains – any ideas? How about swarming social networks? I can’t stop thinking “mob mentality”, but then…

Credit to the author: Tim Barribeau


When the conditions are just right, solitary grasshoppers undergo a terrifying transformation that converts them into masses of swarming locusts that destroy crops. New research reveals why swarming locusts grow much bigger brains than ordinary grasshoppers.

During times of scarcity, locusts default to a solitary form, actively avoiding others of their species. However, when rain comes and plants bloom, the insects undergo a dramatic conversion. It’s thought to be triggered by their legs bumping in to one another due to the increase in population density, and the grasshoppers shrink, change color, and behavior. They eat more, breed easily, and constantly pump serotonin into their body, which encourages the swarming.

So what happens to the brains of these insects when they so dramatically change? They significantly alter their behavior in order to survive as a swarm, which then has a dramatic effect on their brains. Researchers at the University of Cambridge compared the solitary and gregarious modes of the Desert Locust, and found intriguing alterations.

Even though in their swarming form the locusts are smaller than when they’re solitary, their brains are approximately 30% larger. With this transformation, the areas devoted to vision and smell decreased markedly, but there was a huge growth in the areas associated with learning and processing complex information.

In other words, their brains shift towards dealing with the intricacies of the swarm. Says Dr. Swidbert Ott:

Their bigger and profoundly different brains may help swarming locusts to survive in the cut-throat environment of a locust swarm. Who gets to the food first wins and if they don’t watch out, they themselves become food for other locusts. In a nutshell, you need to be brainier if you want to make it in the mayhem that is a locust swarm. As swarming locusts move through the landscape, they face much more of a challenge in finding and assessing potential foods, which may be something new that they have never encountered before.

The researchers hope this will provide more insight into the development and evolution of brains in response to social pressures and the environment.

via Proceedings of the Royal Academy B

Send an email to Tim Barribeau, the author of this post, at tim@io9.com.

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