Nov. 9, 2010 Carotenoid pigments are the source of many of the
animal kingdom's most vivid colours; flamingos' pink feathers
come from eating carotenoid-containing shrimps and algae, and
carotenoid colours can be seen among garden birds in blackbirds'
orange beaks and blue tits' yellow breast feathers. These
pigments play a crucial role in sexual signals. According to the
study's lead author Dr Tom Pike of the University of Exeter:
"Females typically use carotenoid colours to assess the quality
of a potential mate, with more colourful males generally being
regarded as the most attractive." This long-held assumption is,
however, hard to study because we see colour very differently to
fish and previous studies have not taken such differences into
account, instead comparing only the colours perceived by humans.
"The major difference between stickleback vision and our own is
that they can see ultraviolet light, which is invisible to
humans. This may be important because carotenoids reflect
ultraviolet light as we