system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why isn't forest predators, like tigers and lions, fur green?
gpt
Mammals simply do not have the genes to produce green pigments.

All mammal fur and hair is pigmented with some combination of only two kinds of melanin:

* eumelanin makes brown and black fur
* pheomelanin makes yellow and orange fur
* White fur has no melanin.

Those are the only colors of fur that any mammal is able to produce, period.