Why Are Primates So Smart?

Why Are Primates So Smart?

Primates can be defined as the most developed order of mammals. All Primates are classified into one taxonomic order, which divides into two major suborders that differentiate physically from each other after taking different evolutionary lines. The lower primates prosimii commonly called prosimians, meaning "pre-monkey", was the first suborder to evolve and includes animals such as lemurs, lorises, etc.

Anthropoidea was the subsequent suborder to evolve, 90% of anthropoidea is made up by the many different species of monkeys, and the remaining 10% are apes and humans. This suborder is divided into two infraorders, the Platyrrhini also known as the new world monkeys since these are only found in the Americas, and the catarrhini which includes apes, humans and old world monkeys, those found in Africa, Asia and some parts of Europe. There are distinguishable differences between the two infraorders, such as the absence of the pre-hensile tail in old world monkeys, and differences in nose shape and teeth structure, which relates to the differences in diet and olfactory capabilities.

The anthropoids are much larger, have highly developed stereoscopic vision, prehensile hands, show a higher level of intelligence, exceptional cognitive capabilities and have versatile diets which makes them very adaptable to changing environments, these characteristics have made them the most successful animals to populate earth.

Primates have a very important characteristic in that they have a large brain size to body ratio compared to any other taxonomic group, this therefore is one of the reasons primate behaviour is so complex and can explain partially the amazing cognitive abilities shown by non-human primates.

Brain tissue is extremely expensive to maintain, so the large brain primates have developed should represent an important evolutionary advantage that has been carried and constantly developed through evolution. In order to understand the evolutionary importance of having a large brain two hypotheses have been developed by studying the innate behaviours shown by primates towards food and social life. These hypotheses explain the factors that have constantly driven the increase in brain size and the development of certain specific areas in favour of others.

The ecological hypothesis uses the behaviour of primates towards locating and processing food, the use of tools to obtain extractive food such as hard-shelled nuts, and the planning of routes to the various food sources, which suggests that primates are able to form a detailed mental map of its various seasonal food sources. It is also important to note the importance of the diet maintained by primates, which can be seen as the factor driving these behaviours, since extractive foods are very rich in protein and energy, and fruits are seasonal and so a few sources are needed to maintain a constant supply throughout the year.

The second hypothesis explaining primate intelligence is known as the Social Intelligence Hypothesis, this hypothesis is highly supported by comparative studies of neocortical size and group size. This hypothesis argues that social manipulation