So, I'm designing A species of sapient extraterrestrials for a series of short stories, and I've decided it would add flavour if they relied on a species of symbiotic organism to enhance their intelligence to the point of sapience.
The mechanism by which this works is that the symbiote would release hormones and other chemicals which cause the brain to grow faster and for longer than it otherwise would. The symbiote has NO intelligence or cognitive processing on its own. It does NOT override the mind of the host, it only enhances host intelligence.
With that said, what kind of organism exactly should this symbiote be?
Some things that should be the case if at all possible, but which can be omitted if there is no other way to make the general idea work:
- The symbiote should live inside the host.
- The symbiote should be something which primitive societies with minimal knowledge of anatomy might realistically not realise the existence of.
- The symbiote should be something which cannot pass through the placenta or through breast milk, requiring young to be deliberately infected, even if primitive societies do not realise what the ritual by which the young are infected actually does.