John Conroy (@juanitoelgato) returns to talk to us about satellite evidence of underground caverns on the moon and a giant frozen lake on Mars, why having a big brain is a privilege that not every animal can afford and what's killing off the world's reindeer population, is it Christmas? Plus we answer a yahoo question: "Would a horse age differently on the moon?" and a Chan question: "What do horse pants look like?" LAVA TUBES ON THE MOON AND AN ICE LAKE ON MARS https://www.sciencenews.org/article/moon%E2%80%99s-lava-tubes-could-be-colossal mars-ice-more-water-than-lake-superior.html">http://www.space.com/34811-mars-ice-more-water-than-lake-superior.html FOOD-DRIVEN EVOLUTION https://www.sciencedaily.com/releases/2016/12/161221132803.htm http://english.cas.cn/newsroom/research_news/201612/t20161226_172872.shtml REINDEER ARE DOOMED THANKS TO RIGHT-WING CHRISTIANS https://www.sciencenews.org/blog/wild-things/worlds-largest-reindeer-population-may-fall-victim-climate-change Find us at thesciencejerks.com and boardwalkaudio.com/sciencejerks. Email us heyjerks@sciencejerks.com. Subscribe for free on Stitcher or iTunes: https://itunes.apple.com/us/podcast/science-jerks-real-science/id578684997?mt=2