Atavisms: 4 Lost Traits That Returned

Every once in a while, traits thought to be lost forever suddenly reappear, like a dolphin or a whale born with complete hind limbs! Known as atavisms, these occurrences can teach us all sorts of things, like how limbs actually grow.

Hosted by: Hank Green

SciShow has a spinoff podcast! It's called SciShow Tangents. Check it out at http://www.scishowtangents.org
----------
Support SciShow by becoming a patron on Patreon: https://www.patreon.com/scishow
----------
Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever:

Kevin Bealer, Jacob, Katie Marie Magnone, D.A. Noe, Charles Southerland, Eric Jensen, Christopher R Boucher, Alex Hackman, Matt Curls, Adam Brainard, Jeffrey McKishen, Scott Satovsky Jr, James Knight, Sam Buck, Chris Peters, Kevin Carpentier, Patrick D. Ashmore, Piya Shedden, Sam Lutfi, Charles George, Christoph Schwanke, Greg
----------
Looking for SciShow elsewhere on the internet?
Facebook: http://www.facebook.com/scishow
Twitter: http://www.twitter.com/scishow
Tumblr: http://scishow.tumblr.com
Instagram: http://instagram.com/thescishow
----------
Sources:
Dollo’s Law/Atavisms
https://pubmed.ncbi.nlm.nih.gov/7991619/
https://doi.org/10.1016/j.tree.2008.06.013
https://doi.org/10.1002/ajmg.a.36234
Cetacean Hind Limbs
https://doi.org/10.1007/978-1-4899-0159-0_10
https://doi.org/10.1073/pnas.0602920103
https://doi.org/10.1046/j.1525-142X.2002.02033.x
Limpet Shell Twists
https://pubmed.ncbi.nlm.nih.gov/16701270/
https://doi.org/10.1098/rspb.2003.2517
Soil Mite Sex
https://doi.org/10.1073/pnas.0700034104
https://doi.org/10.1002/ece3.5303
https://doi.org/10.1016/0305-1978(92)90056-J
Big Bone Worm Males
https://doi.org/10.1016/j.cub.2014.11.032
https://doi.org/10.1016/j.crvi.2008.10.007
https://doi.org/10.1038/s41467-017-01002-8
https://doi.org/10.1186/1741-7007-7-74

Images:
https://commons.wikimedia.org/wiki/File:Anthracotherium_magnum.jpg
https://link.springer.com/article/10.1007/s12052-009-0135-2/figures/24
https://link.springer.com/article/10.1007/s12052-009-0135-2/figures/2
https://commons.wikimedia.org/wiki/File:Trochita_trochiformis_01.JPG
https://www.inaturalist.org/observations/19706160
https://www.inaturalist.org/observations/35191166
https://www.inaturalist.org/observations/32780129
https://www.inaturalist.org/observations/7073348
https://www.flickr.com/photos/jsjgeology/25447477923
https://www.flickr.com/photos/treegrow/31682185476
https://eol.org/media/6248881
https://www.flickr.com/photos/treegrow/39096881684
https://www.flickr.com/photos/treegrow/26010907628
https://www.flickr.com/photos/scrippsocean/15806618219/in/album-72157647375239253/
https://www.flickr.com/photos/scrippsocean/15806619019/in/album-72157647375239253/
https://www.flickr.com/photos/scrippsocean/15372997583/in/album-72157647375239253/