Editing Red (section)

=== Seeing red ===
[[File:Madrid Bullfight.JPG|thumb|Bulls, like dogs and many other animals, have [[dichromacy]], which means they cannot distinguish the color red. They charge the matador's cape because of its motion, not its color.]]
The human eye sees red when it looks at light with a wavelength between approximately 625 and 740 [[Nanometre|nanometers]].<ref name="Georgia State University Department of Physics and Astronomy" /> It is a primary color in the [[RGB color model]] and the light just past this range is called infrared, or below red, and cannot be seen by human eyes, although it can be sensed as heat.<ref>{{cite web |title=What Wavelength Goes With a Color? |website=Atmospheric Science Data Center |url=http://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html |access-date=2009-04-15 |url-status=dead |archive-url=https://web.archive.org/web/20110720105431/http://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html |archive-date=2011-07-20}}</ref> In the language of optics, red is the color evoked by light that stimulates neither the S or the M (short and medium wavelength) cone cells of the retina, combined with a fading stimulation of the L (long-wavelength) cone cells.<ref>{{Cite book |title=Introduction to psychology|last=Kalat|first=J. W. |date=2005|publisher=Thomson/Wadsworth|isbn=978-0534624606 |edition=7th|location=Belmont, CA|oclc=56799330|pages=[https://archive.org/details/isbn_053462460x/page/105 105] |url=https://archive.org/details/isbn_053462460x/page/105}}</ref>

[[Primate]]s can distinguish the full range of the colors of the spectrum visible to humans, but many kinds of mammals, such as dogs and cattle, have [[dichromacy]], which means they can see blues and yellows, but cannot distinguish red and green (both are seen as gray). Bulls, for instance, cannot see the red color of the cape of a bullfighter, but they are agitated by its movement.<ref name="Ali&Klyne1985">{{Cite book |last1=Ali |first1=Mohamed Ather |last2=Klyne |first2=M.A. |title=Vision in Vertebrates |place=New York |publisher=Plenum Press |year=1985 |pages=174–75 |isbn=978-0-306-42065-8}}</ref> (See [[color vision]]).

One theory for why primates developed sensitivity to red is that it allowed ripe fruit to be distinguished from unripe fruit and inedible vegetation.<ref>{{cite web |url=http://anthro.palomar.edu/primate/color.htm |title=Primate Color Vision |last=O'Neil |first=Dennis |date=March 19, 2010 |website=Primates |publisher=Palomar Community College |access-date=22 April 2010 |location=San Marcos, California |archive-url=https://web.archive.org/web/20110720024858/http://anthro.palomar.edu/primate/color.htm |archive-date=20 July 2011 |url-status=live }}</ref> This may have driven further adaptations by species taking advantage of this new ability, such as the emergence of red faces.<ref name="scidaily">{{cite web|url=https://www.sciencedaily.com/releases/2007/05/070524155313.htm|title=Color Vision Drove Primates To Develop Red Skin And Hair, Study Finds|last1=Hogan|first1=Dan|last2=Hogan|first2=Michele|date=May 25, 2007|website=Science News|publisher=ScienceDaily|location=Rockville, Maryland|access-date=22 April 2010|archive-url=https://web.archive.org/web/20100507093408/http://www.sciencedaily.com/releases/2007/05/070524155313.htm|archive-date=7 May 2010|url-status=live}}</ref>

Red light is used to help adapt [[adaptation (eye)|night vision]] in low-light or night time, as the [[rod cell]]s in the human eye are not sensitive to red.<ref>{{cite web|url=http://www.olympusmicro.com/primer/lightandcolor/humanvisionintro.html|title=Human Vision and Color Perception|website=Olympus Microscopy Resource Center|archive-url=https://web.archive.org/web/20170705094711/http://www.olympusmicro.com/primer/lightandcolor/humanvisionintro.html|archive-date=July 5, 2017|url-status=dead|access-date=Nov 23, 2018}}</ref><ref>{{cite web |url=https://www.pbs.org/wgbh/nova/worlds/stargazer.html#Sensitize%20Your%20Eyes |title=Be a Stargazer |access-date=2007-09-25 |website=Sensitize Your Eyes |archive-url=https://web.archive.org/web/20071012003807/http://www.pbs.org/wgbh/nova/worlds/stargazer.html#Sensitize%20Your%20Eyes |archive-date=2007-10-12 |url-status=live }}</ref>