It's pretty obvious that accumulation of genetic and epigenetic errors -- bit rot -- is a major factor. But there's also a developmental issue. Neoteny played

It's pretty obvious that accumulation of genetic and epigenetic errors -- bit rot -- is a major factor. But there's also a developmental issue. Neoteny played a substantial role in human evolution. And as people get older, they tend to look more and more like adult "prehuman" primates. Bushy eyebrows. Hair on the ears.