Carl Linnaeus, the great Swedish biologist who classified our species, placed insects in a separate group, in part because he believed they didn’t have brains at all. Maybe that’s not such a surprise, because if you behead a fruit fly, it can live pretty much as normal for several days, flying, walking and mating. Eventually, of course, it will starve to death, because no mouth means no food. The reason why insects can survive in a headless state is that they don’t just have a main brain in their heads but also a nerve cord running through their entire body, with ‘mini brains’ in each joint. Consequently, many functions can be performed regardless of whether or not the head is in place.

      Are insects intelligent? Well, that depends on what you mean by intelligence. According to Mensa, intelligence is the ‘ability to acquire and analyse information’. Now, it’s unlikely that anybody’s going to argue that insects deserve to be members of Mensa, but the fact is that they never cease to surprise us with their ability to learn and make judgements. Some things we believed to be the sole preserve of large vertebrates with proper brains also turn out to be within the capabilities of our tiny friends.

      But not all insects are created equal, and there are great differences between them. Those with dull lives and simple habits are the least bright. You don’t need the wisdom of Solomon if you’re going to spend most of your life snugly tucked up in an animal hide with your sucking snout stuck in a vein. However, if you’re a honeybee, a wasp or an ant, you’re more in need of intelligence. The cleverest insects are the ones who look for food in lots of different places and also form close bonds with one another; in other words, the ones that live alongside many others in a community. These critters must constantly be making judgements: is that yellow thing over there a flower with sweet nectar or is it a peckish crab spider? Will I be able to carry that conifer needle alone or will it take several of us? Do I need to take a sip of this nectar to keep myself going, or should I take it home to Mum?

      The social insects divide up jobs, share experiences and ‘talk to each other’ in an advanced way. This requires capacity for thought. To cite Charles Darwin in The Descent of Man: ‘The brain of an ant is one of the most marvellous atoms of matter in the world, perhaps more so than the brain of a man.’ And that was without knowing what we now know: that ants are capable of teaching skills to other ants.

      The ability to teach has long been seen as exclusive to us humans, almost a proof of an advanced society. Three quite specific criteria distinguish teaching from other communications: it must be an activity that only happens when a teacher meets an ‘ignorant’ pupil; it must involve a cost for the teacher; and it must make the pupil learn more rapidly than he/she otherwise would have. The term is used for communication about concepts and strategies, so the honeybees’ dance (see here), which is more about process, is generally not viewed as teaching. However, it turns out that ants are capable of teaching things to other ants, through a process known as ‘tandem running’, in which an experienced ant shows the way to food. This occurs in a European species, Temnothorax albipennis, which relies on landmarks such as trees, stones and others, as well as scent trails, to remember the way from the anthill to a new source of food. In order for several ants to be able to find the food, a she-ant (all worker ants are female, see here) who knows the way must teach it to the others. The teacher runs on ahead to show the way, but constantly stops to wait for her pupil, who runs more slowly, apparently because she needs time to take note of the landmarks they are passing. When the pupil is ready again, she touches the teacher with her antennae and they continue on their journey. The behaviour therefore satisfies the three criteria of ‘genuine teaching’: the activity happens only when a teacher meets an ‘ignorant’ pupil, it involves a cost for the teacher (she must stop and wait) and it makes the pupil learn more quickly than she would have on her own.

      Bumblebees have also recently been inducted into the exclusive little group of creatures who can teach tricks to their peers. Swedish and Australian scientists successfully trained bumblebees to pull on a string to gain access to nectar. They made artificial blue flowers in the form of plastic discs, which they filled with sugar water. When these were covered with a transparent plate of plexiglass, the only way of gaining access to the sugar water was to pull on a string attached to the fake flower. If the scientists only let untrained bumblebees loose on the covered flowers, they didn’t understand a thing: none of them pulled on the string. A great starting point. Then the bumblebees were given a chance to get acquainted with the ‘flowers’, learning about the reward they offered. Gradually, the fake flowers were pushed further and further beneath the transparent plexiglass plate. This time, when the fake flowers were finally pushed fully beneath the plate, 23