system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we have two of some organs (e.g. lungs, kidneys, etc.) but not of others (e.g. liver, pancreas, etc.)?
gpt
Surface area. Our body is constantly filtering via the kidneys and exchanging gas via the lungs. Having twice the amount of alveoli and twice the amount of nephrons helps our body keep up with the amount of absorption, secretion, and exchange necessary to maintain homeostasis. You can technically live without one kidney and one lung, but it puts stress on that organ and requires you to make lifestyle changes to accommodate.