What is the purpose of natural selection?

Natalie had random hand movements when she was two months old. when she was six months old, she used to grab a block with her whole hand. now at the age of ten months, she can grasp the same block with her thumb and forefinger. this sequence of growth in her hand and finger movements is according to the pattern.

This comparative chart is an example of one that might be used by scientists and law enforcement personnel for identification purposes. the chart represents a technological advance called

Which was most likely an effect on society that resulted from improvements in blood handling during world war i and world war ii?