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Wednesday 18 October 2017

The wonder of the organisation in an ant nest - an emergent property

By Jim Hurley - Nature Trail

A Wood Ant nest; Co Tipperary is the species' stronghold.
A Wood Ant nest; Co Tipperary is the species' stronghold.

Organisation in the nest of a colony of ants is amazing yet it is not designed by any individual ant or steering committee of ants. Furthermore, no individual ant has the means to see or appreciate the big picture. Each individual lives for a short while carrying out its simple daily chores but the colony and nest live on growing in both size and complexity. The whole is more than the sum of its individual parts.

The flocking of birds and the shoaling of fish are other examples of this common phenomenon if the natural world. As long as each bird flies a precise distance from, and in alignment with, its nearest neighbour the flock rises and falls, wheels and turns in perfect synchrony as if following a carefully choreographed plan involving months of intensive practice.

We find such matters amazing if not magical. Science explains them via the philosophical concept of 'emergent properties'.

Take table salt as an example. Many people sprinkle salt of their dinner, boiled egg or packet of chips to give it the salty taste that they find agreeable. Salt is a compound of two chemicals: sodium and chlorine. Sodium is a soft metal and is one of the most common chemicals found in seawater. Chlorine is a green, poisonous gas put in drinking water and swimming pools to kill germs.

Sodium is not edible and doesn't have a salty taste. Chlorine doesn't have a salty taste either and is very poisonous. In nature, chlorine doesn't normally occur as a gas; it is most commonly found joined to sodium to make salt in the sea. Since the briny taste of salt is not a property of either the sodium or the chlorine, saltiness is a property that emerges when the two components join.

Saltiness is an emergent property; it is a new property that emerges from the joining of two constituents neither of which possesses the property of saltiness.

Biologists argue that the wonder of organisation in an ant nest is similarly an emergent property. There is a division of labour and while the ants appear to be cooperating with each other and showing admirable care for the queen, her offspring and the welfare of the colony, each individual is simply following a basic set of instincts.

The sum of all the individual, low-level behaviours emerges as what we perceive to be high-level, sophisticated, social organisation. The whole is more than the sum of its individual parts.

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