Uploaded October 2015 | Updated September 2026, 3 weeks ago

Lincoln Chafee just dropped out of the race, but I'm still rooting for him and the metric system!

Darwin and Exceptions to the Rules of Nature

Hidden Lives of Plants A New Look at Orchids

StanEvolve |

Vote for Chafee in 2016!

Name: Darwin and autumn leaves @StanEvolve
Uploaded: 2025-11-22T01:29:31-0400
Duration: 8 min 17 s
Description: Why do tree leaves turn yellow and red in the autumn? Here is a partial answer. The yellow color was in the leaves all along, helping out with photosynthesis, while the red color was manufactured by the leaves as they grew older. Is there a reason for autumn leaves to have bright colors, or is it just a happy (to us human observers) accident?