Kurup, R: Hedonic Symbiotic Treadmill - The Biology of Happiness

Hedonic dopaminergic and serotonergic circuits depend on the extent of archaeal symbiosis. Endosymbiotic archaea generate archaeaons, which have a shikimic acid pathway that produces psychedelic alkaloids such as LSD, morphine, and psilocybin. Tyrosine and tryptophan catabolism can also generate neuroactive alkaloids that contribute to activation of the hedonic circuits. Good and bad things happen, but there is always a return to a set point of happiness. A certain level of archaeal symbiosis is required to maintain a baseline of happiness. Archaeal endosymbiosis leads to Neanderthalization of the human brain, and primitive Neanderthal society was a hedonistic, anarchic society.