Many varieties of bananas have seeds; however, Cavendish bananas, which are the type that most people eat, do not have seeds. Long ago a tetraploid banana was mated with a normal diploid banana, creating a banana that couldn't mate or produce seeds, which is the banana we eat today.
The black dots in the middle of the bananas we eat are immature seeds that will never develop. These Cavendish bananas made up 47 percent of the bananas produced worldwide between 1998 and 2000. The skin of these bananas is green and then turns yellow when they ripen, and ultimately black when they are overripe. However, once they are picked, the bananas won't turn yellow naturally and require ethylene to start ripening again.