That is a very interesting question! There
are many reasons that we need to live on the
surface of the Earth and not inside it. One
reason is that humans have evolved to breath the
exact mixture of gas that is in our atmosphere
(mostly nitrogen and oxygen). Plants create the
oxygen that we breathe, and they can only do
this at the surface of the Earth where they get
plenty of sunlight. Humans also need sunlight to
produce vitamin D, an essential nutrient.
Another reason that we can’t live deep
inside the Earth is that the pressure and
temperature get very high deep underground. The
pressure increases because of the weight of all
of the rock above. Humans would get crushed by
the pressure if they went too deep. The Earth
also gets very hot deep down. The rocks would be
over 550 Fahrenheit if you dug down 10 miles.
That’s way too hot for humans to live!