(Sorry about the slight buzz in Anthony's audio this week. OUR BAD)A team of researchers injected human stem cells into mouse embryos. Just over two weeks later, the team had more mature mouse embryos that contained up to 4% human cells.  These cross-species hybrids, called chimeras, are the first time anyone has been able to create an animal that was made up of as many human cells as these mice. Anthony and Jeff talk about how much human is too human for animals, and whether they'd take a heart from a chimera.  Then, a new study, published  in the journal Integrative Organismal Biology argues that beard hair could collectively diffuse the force of a blow and so may have evolved in response to the need to win male-male battles.  Jeff and Anthony, erstwhile beard growers themselves, discuss the usefulness of a beard in a fight, and whether the science bears out.GET BONUS EPISODES, VIDEO HANGOUTS AND MORE. VISIT: http://patreon.com/wehaveconcerns Get all your sweet We Have Concerns merch by swinging by http://wehaveconcerns.com/shopHey! If you’re enjoying the show, please take a moment to rate/review it on whatever service you use to listen.Here’s the iTunes link: http://bit.ly/wehaveconcerns And here’s the Stitcher link: http://bit.ly/stitcherwhconcerns Jeff on Twitter: http://twitter.com/jeffcannataAnthony on Twitter: http://twitter.com/acarboniToday’s stories were Sent in by Kris Sikes https://bgr.com/2020/05/14/human-mouse-hybrid-chimera/And Mark Nuhfer https://www.livescience.com/beards-protect-face-punches.htmlIf you’ve seen a story you think belongs on the show, send it to wehaveconcernsshow@gmail.com, post in on our Facebook Group https://www.facebook.com/groups/WeHaveConcerns/ or leave it on the subreddit: http://reddit.com/wehaveconcerns