Lottia digitalis Point on the California coast, "L. digitalis" coexists with the similar species, "Lottia scabra", but each occupies a slightly different habitat. "L. digitalis" tends to occupy vertical rock faces or overhangs and certain horizontal ones clothed by algae and barnacles. "L. digitalis" clump together more often, prefer wave-exposed areas, occupy sites further up the shore and are seldom found in rock pools. Both species move about freely when the tide is up but "L. digitalis" settles in a different location at each low tide whereas "L. scabra" tends to home to the same spot. "L. scabra" has a more rugged
Recreational drug use part of the milieu of drug taking. The reasons for drug use appear to have as much to do with needs for friendship, pleasure and status as they do with unhappiness or poverty. Becoming a drug taker, to many people, is a positive affirmation rather than a negative experience.” Anthropological research has suggested that humans "may have evolved to counter-exploit plant neurotoxins". The ability to use botanical chemicals to serve the function of endogenous neurotransmitters may have improved survival rates, conferring an evolutionary advantage. A typically restrictive prehistoric diet may have emphasised the apparent benefit of consuming psychoactive drugs, which