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 evolutionary developmental biology
Jeremy De Silva and Julie Lesnik examined chimpanzee neonatal brain size to identify implications for brain growth in "Homo erectus". This changed the understanding of differences and similarities of post-natal brain growth in humans and chimpanzees. The study found that there was a distinction necessary between growth time and growth rate.The times of growth were strikingly similar, but the rates were not. The paper further advocates the use of fossils to assess brain size in general and in relation to cranial capacity.