Tuesday, November 17, 2009


Every once in a while an article comes out that answers a question I have had in my mind for years. The question: How can insects think with such power when their brain size is miniscule at best? Now I know thanks to a post on Current Biology titled Are Bigger Brains Better?

Attempts to relate brain size to behaviour and cognition have rarely integrated information from insects with that from vertebrates. Many insects, however, demonstrate that highly differentiated motor repertoires, extensive social structures and cognition are possible with very small brains, emphasising that we need to understand the neural circuits, not just the size of brain regions, which underlie these feats. Neural network analyses show that cognitive features found in insects, such as numerosity, attention and categorisation-like processes, may require only very limited neuron numbers. Thus, brain size may have less of a relationship with behavioural repertoire and cognitive capacity than generally assumed, prompting the question of what large brains are for. Larger brains are, at least partly, a consequence of larger neurons that are necessary in large animals due to basic biophysical constraints. They also contain greater replication of neuronal circuits, adding precision to sensory processes, detail to perception, more parallel processing and enlarged storage capacity. Yet, these advantages are unlikely to produce the qualitative shifts in behaviour that are often assumed to accompany increased brain size. Instead, modularity and interconnectivity may be more important.

After reading this amazing piece, one readily understands that efficiency of brain configuration is often of greater consequence than size, something also seen in the extraordinary intelligence of parrots as seen in a earlier BRT post titled Alex, we hardly knew ye.

Not only was Alex smart, (he understood colors, categories and numbers) he also was easily bored if the experiments he participated in were not up to snuff in challenging his intellect.

Seen below is another graphic from the CB writing showing how body mass is a predictor of brain mass in animals.

As follow up, check out Physorg's perceptive take on the CB posting.

Chittka says: "In bigger brains we often don't find more complexity, just an endless repetition of the same neural circuits over and over. This might add detail to remembered images or sounds, but not add any degree of complexity.

To use a computer analogy, bigger brains might in many cases be bigger hard drives, not necessarily better processors."

This must mean that much 'advanced' thinking can actually be done with very limited neuron numbers. Computer modelling shows that even consciousness can be generated with very small neural circuits, which could in theory easily fit into an insect brain.

In fact, the models suggest that counting could be achieved with only a few hundred nerve cells and only a few thousand could be enough to generate consciousness. Engineers hope that this kind of research will lead to smarter computing with the ability to recognise human facial expressions and emotions.

“Machines take me by surprise with great frequency.” - Alan Turing
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