5 Most Incredible Discoveries of the Week Including bone-healing marijuana and new categories for drunks By Jenn Gidman, Newser Staff Posted Jul 18, 2015 5:29 AM CDT 3 comments Comments All right, all right, all right! (Shutterstock) (Newser) – In addition to surprises about Pluto, stories about ancient sperm and ancient dentists make the list of the week's discoveries: Oldest Animal Sperm Found: Scientists exploring an Antarctic island stumbled across history—the world's oldest animal sperm. They found it inside a fossilized cocoon made by some type of worm 50 million years ago. As with many great discoveries, it was kind of by accident. Ancient Tooth Reveals Earliest Dental Visit: Cavemen got cavities, too, and just like us, they had to go to the dentist. Researchers studying a 14,000-year-old infected molar say someone tried to clean it with flint tools—a discovery that amounts to the first known evidence of dentistry. It took a microscope to reveal the work. Scientists Decide There Are 4 Kinds of Drunks: Are you an Ernest Hemingway drunk (no real personality change) or a Mary Poppins drunk (happy and sweet)? A Nutty Professor drunk (uncommonly extroverted) or a Mr. Hyde drunk (hostile and brooding)? University of Missouri researchers broke down imbibers into four distinct personality categories, and one group dominated. Standing Might Be Bad for You, Too: Study after study has told us how bad it is to spend our workdays sitting. Now new research indicates standing may be problematic, too. Researchers had young adults (18 to 30) and an older group (over 50) "simulate" five hours of standing work, with 30-minute lunch breaks and five-minute seated breaks. While some ended up with short-term issues like fatigue, leg cramps, and backaches, there were longer-term issues, too. Pot Helps Heal Broken Bones: There's a new and promising use for marijuana, or at least a compound found in it. Israeli researchers discovered that cannabidiol worked wonders for rats with broken limbs. When rats with mid-femoral fractures were given CBD, the healing process was "markedly enhanced" within just eight weeks. And the treatment did more than just mend bones. Click to read about more discoveries, including how firstborns tend to have higher IQs.