Alfred Russel Wallace, a biologist, naturalist and anthropologist who studied life in the tropics of Indonesia came up with the same idea of natural selection as Charles Darwin and prompted Darwin to publish his Origin of Specie sooner rather than later. He also studied the geographic distribution of species and as as well he was a social activist who criticized capitalism and warned of damage to the environment from man's economic activities.
Cells do need food. In a process known as cellular respiration, cells convert biochemical energy (oxygen as food) from nutrients into adenosine triphosphate (ATP), and then release waste products.
hope this helps.. :D