http://rstb.royalsocietypublishing.org/content/356/1407/381.full.pdf - Fantastic article in general.
Cannabinoid receptors seem to have evolved in the deuterostome superphylum. I've heard sea squirts being quoted as the 'first' animal with an endocannabinoid system but that's a bit harder to verify. Offthehook, it's worth noting that cannabinoids and endocannabinoids evolved separately and quite distinctly. They might happen to interact with the same receptors but it is something of a fluke of nature, though these things happen surprisingly often.
Cannabinoid receptors seem to have evolved in the deuterostome superphylum. I've heard sea squirts being quoted as the 'first' animal with an endocannabinoid system but that's a bit harder to verify. Offthehook, it's worth noting that cannabinoids and endocannabinoids evolved separately and quite distinctly. They might happen to interact with the same receptors but it is something of a fluke of nature, though these things happen surprisingly often.
