Editing Visible spectrum (section)

===Mammals===
Most mammals have retained only two opsin classes (LWS and VS), due likely to the [[nocturnal bottleneck]]. However, old world primates (including humans) have since evolved two versions in the LWS class to regain trichromacy.<ref name="Hunt-2001"/> Unlike most mammals, rodents' UVS opsins have remained at shorter wavelengths. Along with their lack of UV filters in the lens, mice have a UVS opsin that can detect down to 340&nbsp;nm. While allowing UV light to reach the retina can lead to retinal damage, the short lifespan of mice compared with other mammals may minimize this disadvantage relative to the advantage of UV vision.<ref>{{cite journal |last1=Gouras |first1=Peter |last2=Ekesten |first2=Bjorn |title=Why do mice have ultra-violet vision? |journal=Experimental Eye Research |date=December 2004 |volume=79 |issue=6 |pages=887–892 |doi=10.1016/j.exer.2004.06.031|pmid=15642326 }}</ref> Dogs have two cone opsins at 429&nbsp;nm and 555&nbsp;nm, so see almost the entire visible spectrum of humans, despite being dichromatic.<ref>{{cite journal |last1=Neitz |first1=Jay |last2=Geist |first2=Timothy |last3=Jacobs |first3=Gerald H. |title=Color vision in the dog |journal=Visual Neuroscience |date=August 1989 |volume=3 |issue=2 |pages=119–125 |doi=10.1017/S0952523800004430|pmid=2487095 |s2cid=23509491 }}</ref> Horses have two cone opsins at 428&nbsp;nm and 539&nbsp;nm, yielding a slightly more truncated red vision.<ref>{{cite journal |last1=Carroll |first1=Joseph |last2=Murphy |first2=Christopher J. |last3=Neitz |first3=Maureen |last4=Ver Hoeve |first4=James N. |last5=Neitz |first5=Jay |title=Photopigment basis for dichromatic color vision in the horse |journal=Journal of Vision |date=3 October 2001 |volume=1 |issue=2 |pages=80–87 |doi=10.1167/1.2.2|pmid=12678603 |doi-access=free |s2cid=8503174 }}</ref>