Uploaded February 2009 | Updated September 2026, 1 hour ago

---

How does your foot know it should be a foot? How come you don't grow ears on your arm? Find out in "Regulatin' Genes". ↓ More info and resources below ↓

Thanks to Jake Wachtel for directing/editing and Bob Siegel for the cameo. Special thanks to DERRICK DAVIS, world-renowned econ/public-policy major, for showing some love to hum bio.

Subscribe to Science With Tom: bit.ly/1Hf68JW

Website: sciencewithtom.com
Facebook - facebook.com/ScienceWithTom
Twitter - twitter.com/ScienceWithTom
Instagram - instagram.com/sciencewithtom
Snapchat - +ScienceWithTom