Smith was born in Broken Hill, Northern Rhodesia, now Kabwe, Zambia. His father was a metal worker who opened a sheet metal factory and then bought a cattle ranch.
As a baby, Smith was sick with cerebral malaria for ten days, but made a full recovery. He spent the first years of his life on his father's cattle ranch which consisted of 12,000 hectares of forest, hills and savannah. On the ranch his companions were the sons of the ranch workers, small black boys with the same interests and preoccupations as Smith. With his companions he ranged through the bush, hiking, hunting, and trapping birds and small mammals