system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is brown such a "default" colour in nature?

Brown seems to be such a default colour for things in nature and in day to life. Why is it so common for things to be or turn this colour in contrast to the vast array of other colours around?
gpt
Because “brown” is a result of mixing pretty much any two/three pigments (try it with red and green). That being said, it’s also because plants have usually two or three types of pigments and carotenoids are useful and abundant, and carotenoids range from yellows, to oranges and reds. For mammals that need to camouflage, it was useful to mimic the environments that are murky/shadowy especially since most mammals evolved from animals active in the mornings/evenings - hence ones producing melanin hit the jackpot and blended well with “murky” undefined colours such as varieties of brown.