Sunday, November 7, 1999
AS recently as 1960s it was boldly claimed that "man is the only tool-making and tool-using primate", and our species was referred to as "man the tool-maker". This ability had long been considered one of the features that set man apart from all other animal species, but about 35 years ago Jane Goodall, the zoologist, discovered an amazing fact. In the wild chimpanzees, too, use tools in their daily life. She was astonished to see these primates using twigs to fish out termites from their mound nest.
It has also been proved that they do not pick up just anything for the use. Instead, they plan in advance. Their tools are carefully selected and prepared. Like many species that are thought of as exclusively herbivorous, chimpanzees, too, in reality have a strong urge for non-vegetarian food which supplements their diet in many ways. One such source is insect world. Apes are regular seekers of ant nests or termite hills, and when they find one they break a small hole in it, but that is not enough to reach the insects. To probe deeper a chimpanzee will seek out a smooth twig, and if it does not find one it well improve upon any other less suitable twig by breaking it to a manageable length and removing all side-projections so that it will not snag as it is withdrawn from the hole.
It is a sight to watch chimpanzees fishing for termites. Once a required tool is made, it is laboriously inserted into the hole and pushed right in. This action is done with great concentration and restraint, and then the animal gently withdraws the tool with defenders of the nest clinging firmly to the intruder. The chimpanzee gently wipes it sideways across its mouth and swallows the insects.
In a situation when no suitable tool is available nearby the nest, these animals have been seen to travel for up to half a kilometre to locate one. Not only that, once an efficient probing-stick has been made, it may be carried around from nest to nest as its owner searches for a good site for its termite fishing. And in the course of probing if a favourite tool is broken, it is repaired and then reused.
Not only that, experiments have shown that with little encouragement chimpanzees in captivity can learn to use tools in a remarkably sophisticated way. It has been found that they can successfully insert and turn keys to open locked doors, they can handle paint-brushes to make simple and abstract patterns on paper, they can obtain food by inserting coins in slot machines, they can dislodge objects by aiming and hitting accurately.
Chimps have been observed doing many things in the wild which require certain amount of intelligence. They crack nuts with the help of stones, and this is not a casual activity. The stones and the nuts in question are not found together. Each had to be collected separately and then brought together at a suitable place. It has been observed that chimps carry whole armful of nuts to a flat spot along with a carefully selected stone and then methodically crack them one by one. In case of thirst they have been seen to fashion a sponge from a wad of leaves and dip it into the small pools of water that form in certain tree-forks. Soaked with water, the sponge is then raised to the lips and the liquid sucked from it. These animals usually lap water, but when the quantity of water is not sufficient then the above method is adopted.
It is not only these primates who use implements, there are some other mammals and birds too. For example certain monkeys batter crabs against hard stones to crack them open.
Mongooses and skunks use
special body movement to fling birds eggs, like
that of ostrich which they cannot break easily, against
rocks, as a way of cracking them open. Woodpecker finch,
a bird of Galapagos Islands, employs a sharp twig or a
large cactus spine as a tool when searching for grub or
insects that live hidden inside wood, cracks and
crevices. It impales them by cactus spine. Song thrush
uses large stones as an anvil against which it can smash
open snails. Sea otters too use stones as an anvil, like
song thrush, to break open shellfish.
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