Scientists have several ideas why humans can high-five each other instead of, say, high – four or high – six. One theory suggests four fingers and a thumb on each hand are the perfect number and length to grip objects firmly. (Another study suggests we can grasp most things with just our thumb and index finger if necessary; the other four fingers are spares.)
The process of evolution determined the most beneficial number of fingers and toes for our survival. Pandas, after all, have thumb like digits to help them grasp bamboo shoots, while some birds have quadruple digits for perching and tucking away during flight. Occasionally, babies are born with extra fingers and toes (a condition known as polydactyly), but those additional digits have never offered enough of an edge to survive to later generations. In other words, evolution determined that five fingers per hand are just right for humans.
Picture Credit : Google