Why can't people fly?

Answer 1

People do not have wings; so the Wright brothers invented powered craft that could fly.

People can not fly without the help of machines do to many reasons. Some of the main reasons are our bodies are not aerodynamic, our bones are not hollow, and we do not have wings. There are many ways we can fly do to technology though from paragliding to planes we can explore the sky.

Answer 2

Answer

People can't fly because first of all we aren't aerodynamic enough and second of all unlike birds, people don't have air sacs, hollow bones, or a lightweight body. Well we might have a lightweight body, but they need wings to fly and we don't have enough strength to hold up a wing structure that could make them fly. The only thing we could get to fly is planes, hang gliders, and other flying mechanics we made. Also birds can breathe in a lot of oxygen with their air sacs, but we can't. Birds need that oxygen for flying up high because the higher up you go, the less oxygen is there. Plus I don't think it'll be easy to breathe correctly up there because you're using up a lot of energy and you need oxygen to pump to your blood.

Answer

Basically it's down to strength-to-weight ratio. Even if we made us some wings we'd be too weak for our weight, or too heavy for our strength to be able to overcome gravity.

Birds are adapted to flying already from the start, with lighter skeletons, higher metabolic rates and huge flying muscles, all of which contributes to give them a better strength-to-weight ratio.

Answer 3

People are too heavy for the speed they can run to be able to fly.