We judge animal‘s intelligence by its ability to use tools. It requires skills and ingenuity. Furthermore, animals somehow manage to pass their skills to the younger generations, which shows that they do build upon a foundation. However, how to they choose appropriate tools for the job? An international research showed that macaques select rocks to crush nuts in accordance to their own body size.
There are two major philosophies when selecting tools – you can match them to your own strength or to the job at hand. Macaques appear to go with the first option when cracking oil palm nuts open. They choose a rock and just smash the nut until it is open – they don’t make tools. Meanwhile chimpanzees use bigger rocks to process the same nut and wild macaques use bigger rocks to crush sea almonds. Scientists say that these findings are important for the field of primate archaeology and could even tell something about how early humans used their tools.
When humans developed their own stone tool technology nearly 3.3 million years ago they also used a combination of a hammer rock and an anvil rock. This can be observed in primates today, even though up until recently only chimpanzees in Western Africa have been observed to open oil palm nuts using a stone hammer and anvil. Wild long-tailed macaque monkeys in Thailand are now seen using this technique, which has not been observed before. It is quite interesting, because oil palm nuts are not native to the islands and have been introduced only a couple of decades ago. This means that macaques, which typically fed on sea food, adapted themselves to this situation. It is also interesting that scientists are figuring this out without direct observations.
Macaques are better left alone now, but research has to continue. That is why scientists applied archaeological methods to research their use of tools. Scientists analysed marks on rocks, to see how they were used – monkey leave their tools behind, as they are not made, but found. Dr Tomos Proffitt, leader of the research team, said: “It appears that macaques are choosing stones based on what raw material is available rather than the best material for the job, but this is where we will develop our research to further understanding”.
Using tools is difficult – it does require intelligence. It is interesting to see how different animals use tools differently and how it affects their behaviour.