magazine issue 12 2006 / Issue 1

On Scaffolds and Sweet Potatoes

• written by Arno van Voorst

For example did the same Imo mentioned above discover how to wash a different type of food: wheat. The Japanese researchers had scattered this food, but had by doing so created a new dilemma for the macaques: how can you get fine wheat separated from sand? Imo found a simple, yet effective solution: she made a huge ball of the sand and wheat, walked up to the water and dumped the ball in the water. As sand is heavier than wheat, the sand sank to the bottom, whereas the wheat stayed afloat and became easy to collect.

Their next major discovery was that the macaques started to flavour their potatoes. Apparently sweet potato does not have such a great taste, as macaques changed again in their washing habits. Instead of washing their potatoes in sweet water, the macaques moved to the sea to wash their food. There, they bit holes in the potatoes and washed them. The result of this washing was that the potatoes got a nice salty taste.

What most people should know is how revolutionary this was in other ways as well: the Koshima macaques were originally afraid of the sea and extremely reluctant to even put a single toe in the water. Through the habit of salting their potatoes however, the macaques started to venture deeper and deeper into the water to flavour their foods. And they even brought their young with them while washing. The result of this behaviour was that the young became better and better acquainted with the water and very soon started to play and swim in the sea.

During this change from an animal that lived exclusively in the forests to an animal that spent lots of time around and in the water, the macaques made various new discoveries. Some of the elderly males found out that fish aren’t just strange animals with shiny skins, but are also highly edible, not to mention quite tasty. Fish eating soon became a new habit among the macaques, along with catching limpets and octopus from pools. Quite a change, especially when you consider that macaques prefer life as a vegetarian, with only occasional insects to add to their meal.

Finally, the researchers also discovered that, due to the fact that the macaques had to carry their balls of wheat and heavy potatoes with two hands, the animals started more and more to walk on their hind legs when carrying their food.

All of these changes took place in a time span of around 30 years.

What is the most interesting about these findings? It is simple: by feeding the macaques, the scientists had been responsible for a birth of a completely new life style among the animals. The original potato washing habit had triggered a new habit – the separating of wheat and sand – and these two had helped to trigger the playing and swimming in the water. In the end, these two pairs of behaviours stimulated each other: the washing of food encouraged to stay and play in the water, whereas the playing in the water encouraged the animals to stay near the sea and wash their food.

One single change in behaviour can therefore lead not only to new behaviours in the same domain – that of food washing in general – but can also switch to other domains of behaviour. In the end, such changes can have such profound effects or become such a complex network of habits that support each other, that the original habit is no longer required to keep the entire life style existent. Or, simply said: even if you remove the potatoes the animals will continue to show their new sea based life style. The washing of potatoes is therefore more than an example of animal culture: it is also a prime example of a scaffold.

Implications of scaffolds

So what is the value of the appearance of scaffolds in animal culture? As mentioned above, scaffolds are rarely found, as the scaffold is often destroyed after the structure is finished. That such a scaffold was found and so well documented is a rarity. It also demonstrates that a scaffold can be basically anything that causes some change. It does not by necessity have to be a phenomenon of any great importance at all – washing sweet potatoes isn’t the most amazing thing in the world – to have an effect. And not just any effect. This report also shows that the changes that can be caused by scaffolds are profound. The washing of potatoes was not the end result, but was actually the seed from which completely new sorts of behaviour sprang forth. Scaffolds can be important.