Babies full of cannabis
Here’s an interesting one. The brain and nervous system uses endocannabinoid transmitters and receptors, the same receptors cannabis works on to produce its signature effects. These are believed to fulfil various roles, from memory to metabolism, but their overall purpose is still debated.
One theory, that I came across in a presentation in my student days, is that we’re flooded with natural cannabis when we’re born. Think about it: you’re a very small, still-forming human and in a very messy and intense sequence of events your universe has just gone from a warm wet sack to a sterile hospital room. That should prove intensely traumatic. But not if you’re “stoned”. Think about it some more: you’re unnaturally relaxed, and inexplicably hungry. Very useful traits in a newborn.
This may have stemmed from the claim that breast milk is full of cannabinoids, but I’ve not been able to track down any reliable studies supporting this notion. Shame, it’s quite an intriguing idea.