An incredibly profound observation of the effects of methylendioxymethamphetamine (MDMA) on octopuses was just published this week in Current Biology. The findings of the study titled, A Conserved Role for Serotonergic Neurotransmission in Mediating Social Behavior in Octopus, suggest incredible implications for how social behavior is built into the very molecules coded by our DNA.
Researchers chose the octopus because they are one species on this planet that seemingly couldn't be further from a human biologically speaking. As the study points out, Human and octopus lineages are separated by over 500 million years of evolution and show divergent anatomical patterns of brain organization. One of the major differences is the function and construction of the nervous system.