>>13013091Even if you could figure out a way to engineer chloroplast production in a human, humans don't have a high enough surface area to mass ratio to make photosynthesis worth it. That's why only very small animals have evolved the mechanisms to absorb chloroplasts.
>But trees are huge!Yes, but over 90% of a tree's mass isn't alive. Only the leaves and a very small layer of cells on the outside of the roots and beneath the bark is actually alive. And the rest of the mass is almost entirely composed of high surface area leaves. Photosynthetic skin wouldn't even produce enough energy to be noticeable unless you walked around naked with grow lights blasting every inch of your skin 12 hours a day.
