This is a collection of theories and factors, that may have some positive effect on the evolution of an intelligent species. For the real thing, it is most probably more than one factor, and it's hard to say which one is the "real one". Some are serious, some are very theoretical, some are completely imaginary (or silly). Let’s see what we come up with.
What is the list useful for? Well, if you are creating another race or civilization, it is always useful to think outside of the box - and this is one such inspiration.
- social existence/living - no guarantee by itself, it is a crucial factor many theories build upon it. It is more than the anonymous existence in an insect swarm or a rat pack (though both can demonstrate a certain cunning in their actions as a group entity). It enables pack hunting and passing on of skills, politics and more complicated personal relationships. Speaking of...
- political existence - or lying, cheating and generally deceiving your fellow beings. Living in a group makes it necessary to read the intentions of others, and even better, to manipulate them. Such feats of thinking reward brain power, which can be used for other purposes, too. (Now think of a civilization, that appreciates this.)
- tools - also a sign of thinking, not a proof. It has been theorized, that extensive tool use and their manufacture account for increasing intelligence with developing manual skills, knowledge of working various materials and the finding of new applications.
- higher being(s) - on the one side, the Creator God(s), on the other side, aliens, some other, already intelligent being(s) made it so that people can think. They may or may not stay around.
- changing environment - often mentioned, large changes force existing lifeforms to adapt. Some lifeforms may be moving into a different territory, permanently or as a part of a periodic migration. Same goes for new predators/competition for the lifeform.
- sex - not as such, if a certain preference for partners lasts for long enough, it will change the species. Some theories hold the more intelligent individuals are more attractive. Others consider our obsession with youthful looks to be important: if the younger/immature looking partners are preferred, it leads to a longer period of maturing. If the species can survive it, this enables the development of larger brains and a longer childhood, that is more inclined to learning.
- radioactivity - the explanation for everything, whether it is exceptional solar flares, or a supernova exploding nearby, higher radioactivity triggers a higher rate of mutations. Some of them happen to be beneficial enough to confer that necessary extra kick.
- blind chance - intelligence just happened. It may not be an elegant explanation, but hey, it can’t be completely rejected.
- distributed thinking power - where an individual is a mere unit, large groups demonstrate the ability to learn and adapt to their surroundings. Larger groups could cross the boundary. This could also apply to colony lifeforms and other nonstandard candidates.
- drugs - through the intake of specific drugs, hormones or other chemicals, the existing neural system is uplifted enough to change its functionality or physiology (the "Harold & Kumar theory of intelligence").
- disease - a sickness, such as cancer, could have an unexpected outcome if the brain/neural system could tolerate its existence. The question of inheritance stays open (leading to odd customs like eating brains of the ‘smart ones’ after death).
- multimorphism - individuals of a given species specialize on various functions (like hunters and those remembering the spoils and prey, or primitive breeders and their protectors). With time could the nascent intellect grow in all the members of the species, there could stay a sharp divide, or they could split into two distinct subtypes. Also note exceptional specimens like queens.
- opposable thumb - a certain anatomical feature turns out to be eminently suitable for other purposes (like tool use), supporting the thinking process and raising the chances of its owners to survive.
- rock'n'roll - primitive humanoids discovered music, the generation of rythms and harmonies leads them towards more complex thinking and coordination of their activities. Who knew?
- telepathy - a species has accidentaly received the gift of reading thoughts. The race to a better interpretation of thought patterns makes them better predators, worse prey, or both. The brain is extra.
What is your theory?