July 23, 2015 â Teens using marijuana for medical reasons are 10 times more likely to say they are hooked on marijuana than youth who get marijuana illegally, a new study shows. The study is the first to report on a ... Slow to Mature, Quick to Distract: ADHD Brain Study Finds Slower Development of Key Connections.
Define prehistoric. prehistoric synonyms, prehistoric pronunciation, prehistoric translation, English dictionary definition of prehistoric. also preÂ·hisÂ·torÂ·iÂ·cal adj. 1. Of, relating to, or belonging to the era before recorded history. 2. Of or relating to a language before it is first recorded...
Unlike the Paleolithic, when more than one human species existed, only one human species (Homo sapiens sapiens) reached the Neolithic. The term Neolithic derives from the Greek Î½ÎµÎ¿Î»Î¹Î¸Î¹ÎºÏÏ, neolithikos, from Î½Î­Î¿Ï neos, new + Î»Î¯Î¸Î¿Ï lithos, stone, literally meaning New Stone Age. The term was invented by Sir John Lubbock in 1865 as a refinement of the three-age system.