Different lineages of plants have evolved the ability to make many chemicals that have adverse physiological and psychoactive effects, presumably because such effects interfere with and limit herbivory. Due to constant observation on the effects of consumption of such plants by livestock, as well as by direct experimentation, people have discovered the medicinal and psychoactive effects of consuming such plants. The active drugs isolated from these plants and have been adopted for both medicinal and hedonistic purposes, despite the often overall negative consequences to the users. The high demand for these drugs, due in large part to their addictive nature, combined with the globalization of commerce in the last few hundred years, has led to extensive global trade in these compounds. This has in turn often caused serious social dysfunction. Attempts by governments to restrict the consumption of these drugs by its citizens (the so-called “wars on drugs”), by, among other things, limiting imports, have led to wars between countries and, sometimes, to political instability in either producing or consuming countries.