system
Given the following post, respond as if you're commenting on Reddit:
human
Why is human night vision so bad compared to many other mammals?
gpt
we lack a *tapetum lucidum,* which many animals have.  It's a reflective layer behind the retina that reflects back any light that missed the photoreceptors in the 1st pass-through, imnproving night vision.  It's the reason cat's eyes glow when you shine a light directly at them.