Leaping Marsupials!

There seems to be much general amusement concerning the wallabies in Tasmania suspected of creating 'crop circles' after getting stoned on opium poppies (http://news.bbc.co.uk/1/hi/world/asia-pacific/8118257.stm). Apparently, Tasmania is where the greatest legal concentrations of the poppy are grown to provide material for the medical manufacture of morphine and related materials. As far as the wallabies are concerned, the poppies are just an unfamiliar, rather succulent food item (the plant is alien to Tasmania). All mammals have morphine receptors in their brains to enable them to respond to their own natural pain-relieving chemicals (the so-called 'endorphins') that are released in emergencies (when there is no time to 'worry' about aches, knocks and bruises). The opium poppy has essentially manufactured an endorphin-shaped molecule concentrated particularly in its sap to protect its precious seeds and tissues from being eaten by animals. It's amazing what trouble these plant chemical defense mechanisms cause in humans. So don't sneer at the wallabies. Crop circles are quite a minor problem.