The 'Nice' List: 5 Most Incredible Discoveries of the Week Including a tumbling lake and having a ball with Hitler By Newser Editors, Newser Staff Posted Dec 25, 2015 4:19 AM CST Updated Dec 26, 2015 5:06 AM CST 1 comment Comments Ho ho h-oh my goodness, what have we here?! (Shutterstock) (Newser) – How a mom's age affects her first kid's smarts and century-old letters to Santa make the list: Science Explains Rudolph's Red Nose: A Dartmouth anthropology professor says Arctic reindeer are—at least among mammals—uniquely qualified to see ultraviolet light, which is more common in winter months. The problem is fog messes up the process, and that's where Rudolph's nose comes into play. There's just one issue with his schnoz. Yes, Adolf Hitler Only Had One Testicle: There's been speculation that Hitler was down a ball for years. First historians postulated the Fuhrer's missing genital was a shrapnel casualty from World War I. But recently analyzed medical documents that surfaced in 2010 suggest that Hitler had what's called "right-side cryptorchidism." Find out what that means, and what his childhood doctor had to say about his junk. A Canadian Lake Has Fallen Off a Cliff: In June, Canadian officials warned that a nameless lake in the Northwest Territories was about to fall off a cliff. It did in July when a section of ground ice that dates to the last ice age gave way, sending roughly half of the lake's 1 million cubic feet of water cascading into a valley below in a five-story waterfall that lasted two hours. Check out the time-lapse video of the muddy, impressive collapse. Mom's Age Affects Child's Intelligence: Researchers studied data on 18,000 kids and came up with interesting results: Children born to first-time moms who were in their 30s have better cognitive scores and "behavioral outcomes" than first-born children with mothers in their 20s and in their 40s. The 30-something moms were more likely to be better educated and have healthier lifestyles than their 20-something counterparts. But the possible reason they beat out the 40-somethings was a bit of a surprise. Man Opens Fireplace, Finds Century-Old Letters to Santa: When Peter Mattaliano decided to redo the fireplace in his NYC apartment, he called his construction-savvy brother to help him bust open the sealed unit. They ended up unearthing 100-year-old letters written to Santa by two children named Mary and Alfred—and their story is so poignantly touching that Mattaliano actually bought gifts for them this year. Click to read about more discoveries.