Abstract
One of the factors contributing to human dominance among animals is the ability to translate intelligence and imagination into tangible technology. During the last two million years, members of the human lineage have doubled their brain size, despite the fact that neural tissue is metabolically expensive, suggesting that strong selective pressures were driving the process. Some of these were clearly the advantages bestowed by technology, such as the management of fire and the use of more and more sophisticated tools and weapons.
But if technology can bestow such valuable advantages, why have many other animals not followed this course to the same extent? It seems to me that there are at least five obvious constraints that would apply to any candidate for the role of a ‘technologically competent animal’. Although some are applicable only if the candidate were a mammal, they are:
1. A critical minimum brain size. As was emphasised by Phillip Tobias as long ago as 1971, the human brain is characterised by a very large number of ‘extra neurons’, over and above those needed to handle the basic functions of the body. For human-style intelligence, it seems that a volume of at least 500 cc of ‘extra’ neural tissue-hardware is required, so a constraint is imposed on the minimum size of a mammal that could accommodate this. The constraint does not seem to be as rigidly applied in the case of birds.
2. Suitable appendages for manipulating objects related to the technology in question.
3. A social organisation that would promote the collective effort required for the successful fulfilment of any major technological undertaking.
4. A language-like communication system that would allow the exchange of concepts between individuals.
5. Appropriate birth-canal adjustments to allow the passage of the offspring's large head in such technologically competent mammals.
Various animals fulfil these requirements to some extent and could go on to become completely technologically competent in the course of future evolution, given the appropriate selective pressures. Some such animals are discussed in this paper.
Résumé
Un des facteurs contribuant au succès de notre espèce réside dans sa capacité à traduire son intelligence et son imagination en une technologie performante.