A lot of humans need or want braces to fix their crooked teeth, but why do you never see a dog walking down the street with headgear? Our ancient ancestors and mac and cheese may be to blame! Hosted by: Hank Green ---------- Support SciShow by becoming a patron on Patreon: www.patreon.com/scishow ---------- Dooblydoo thanks go to the following Patreon supporters—we couldn't make SciShow without them! Shout out to Kevin Bealer, Mark Terrio-Cameron, KatieMarie Magnone, Patrick Merrithew, Charles Southerland, Fatima Iqbal, Benny, Kyle Anderson, Tim Curwick, Scott Satovsky Jr, Philippe von Bergen, Bella Nash, Bryce Daifuku, Chris Peters, Patrick D. Ashmore, Charles George, Bader AlGhamdi ---------- Looking for SciShow elsewhere on the internet? Facebook: www.facebook.com/scishow Twitter: www.twitter.com/scishow Tumblr: scishow.tumblr.com Instagram: instagram.com/thescishow ---------- Sources: www.wired.com/2011/11/agriculture-jaw-shape/ www.pnas.org/content/108/49/19546 journals.plos.org/plosone/article?id=10.1371/journal.pone.0117301 www.ncbi.nlm.nih.gov/pubmed/19514263 www.sciencedirect.com/science/article/pii/S004724840400051X rspb.royalsocietypublishing.org/content/early/2011/06/07/rspb.2011.0971