study published in the Journal of Experimental Biology on July 6 found that drugs such as methamphetamines that make their way into the world’s waterways through human waste can actually cause fish to become addicts, thereby impacting the natural balance of ecosystems.
According to authors of the study, fish have nervous systems similar to human beings and are able to develop drug addictions "such as behavioral dependencies related to the dopamine reward pathway." In the study, researchers observed brown trout because, while the species is native to Europe, brown trout can be found in all continents, excluding Antarctica. "Furthermore, brown trout has been employed as a model species in toxicology (e.g.