Intuition
Is intuition a faculty possessed by all living things?
One of biology’s greatest mysteries can be found inside the trunk of the oak tree. That’s where you’ll find the larva of the Capricorn Beetle. It’s a rather unremarkable creature except for the fact that it acts with remarkable foresight.
The larva of the Capricorn Beetle starts life about the size of a long grain of rice and ends up, three years later, fully grown, at about four centimetres long. It’s a simple creature with mandibles at one end, an anus at the other, and a muscular tube in between. It’s gray-white, and naked, except for a few short hairs and some small protuberances on its belly and back, which are its vestigial legs.
This simple little creature spends the entire three years of its larval stage creating a tunnel in the trunk of the oak, excavating the tunnel at one end and filling it up with its excrement at the other. It’s a tunnelling, eating, and digesting machine with very little ability to know anything of its environment. Presumably because there’s not much for it to see in the pitch black of the trunk, it’s completely blind. Presumably because the only noise it could hear would be its own chomping, it’s completely deaf. Presumably because of its monotonous diet, it has no taste-buds; and because the only things it could smell would be the fresh wood in front of it and its waste behind it, it has no sense of smell. Its one and only known sense is its sense of touch.
A large number of beetles have larvae that live exclusively on wood, and since they live exclusively within the trunks of their trees we can be pretty sure that they know nothing of the world outside - from the time they’re born to when they penetrate the bark and emerge as beetles. But the behaviour of the larva of the Capricorn Beetle as it prepares to change from grub to beetle should make us wonder.
When the time draws near for the larva to change, or ‘pupate’, it seems to lose the instinct that has kept it safe inside the trunk and away from the beaks of hungry birds, and it tunnels toward the outer edge of the bark. This action puts it directly in the way of danger - because many birds are highly attuned to detecting and removing insects from the bark of trees. So why does it do this? Because its beetle form has no apparatus to tunnel! If the grub pupated within the trunk the emerging beetle would awaken inside a beautifully carved oak coffin; and there it would perish. We can see how evolution would favour action that prevents this, even if that action brought a level of danger itself, but the grub's sense of the limitations of its future form goes further.
On reaching the outer bark the grub gnaws out a pupal chamber large enough for it to turn around in. It then regurgitates a chalky substance, which hardens as it dries, and it uses this as render on the chamber’s outer end. It seems to 'know' that while its beetle form cannot chomp through wood, it is capable of dislodging this thin port-hole. The grub then has the extraordinary 'good sense' to lie down to pupate with its head toward this outer end. It seems to 'know' that while it can turn around in its pupal chamber, its beetle form with its stiff wing-cases, cannot. If it pupated with its head pointing the other way, the emerging beetle - unable to turn around and use its mandibles to open its escape hatch - would be imprisoned and die. But the grub never pupates facing the wrong way, so no such tragedy ever confronts it as a beetle. After it pupates it wakes and finds itself in the form of a beetle, inside a capsule from which it can easily escape. And so it does, able to see, smell, taste and hear for the very first time … and flies off to find a mate.
How does the grub 'know' that its future form is incapable of something that is, essentially, its only skill - that is, burrowing through wood? How does the grub 'know' that its future form is capable of dislodging the chalky membrane? How does the grub 'know' that its future form is unable to turn around inside the pupal chamber? Such things are hard enough to understand when the creature in question has faculties such as sight and hearing and we can see that it is capable of awareness and response to its environment. But how can it happen with a virtually senseless grub?
The answer is: it cannot. I've put the words 'know' and 'good sense' in inverted commas because I don't believe that the grub knows the limitations of its future form, or really has good sense, but I find it hard to say that its only sense is its sense of touch. All living things seem to have another sense: instinct, something hard-wired by evolution, but something not easily explained. There are many examples of instinctive creatures that possess extrasensory perceptions: migratory urges, symbiosis, the movement of animals seemingly governed by a collective psyche, and all of these suggest perceptions that cannot be traced to the activity of physical sense-organs alone.
Intuition: (noun) The act or faculty of knowing or sensing without the use of rational processes.
Intuition is a word that is rarely used in biology, but the above meaning of the word is quite appropriate in that context. There are many questions here, such as: what is the difference between instinct and intuition? How is instinct hard-wired into the brain? And, could intuition be a faculty possessed by all living things?
The information on the Capricorn Beetle was sourced from the works of the English Biologist E. L. Grant Watson.