Human hair growth
The three stages of hair growth are the anagen, catagen, and telogen phases. Each strand of hair on the human body is at its own stage of development. Once the cycle is complete, it restarts and a new strand of hair begins to form. The rate or speed of hair growth is about 1.25 centimetres or 0.5 inches per month, or about 15 centimetres or 6 inches per year.
Human brain
As a hominid brain, the human brain is substantially enlarged even in comparison to the brain of a typical monkey. The sequence of human evolution from "Australopithecus" (four million years ago) to "Homo sapiens" (modern humans) was marked by a steady increase in brain size. As brain size increased, this altered the size and shape of the skull, from about 600 cm in "Homo habilis" to an average of about 1520 cm in "Homo neanderthalensis". Differences in DNA, gene expression, and gene–environment interactions help explain the differences between the function of the human brain and other primates.