Hair Analysis

In recent years, a University of Toronto laboratory pioneered the use of neonatal hair to show exposure to drugs of abuse in pregnancy. Drugs such as cocaine, methamphetamine, heroin, etc., accumulate in the neonatal hair during its growth and thus serve as a long term “memory” of what happened during fetal life. The hair analysis method used by Dr. G. Koren's research group revolutionized the diagnosis of in utero exposure to drugs. A recent study by scientists from Medical University of Vienna traced the origins of hair to the common ancestor of mammals, birds and lizards that lived 310 million years ago. The study found chickens, lizards and humans all possessed a similar set of genes that was involved in the production of keratin . In chickens and lizards, the keratin produced was found in their claws, but in mammals it was used to produce hair. The scientists involved were still searching for the mechanisms that allowed mammals to use the keratins of animal claws to produce hair

The soft, fine hair found on many nonhuman mammals is typically called fur.

Historically, some ideas have been advanced to explain the small amount of body hair in humans, as compared to other species. However, recent research on the evolution of lice suggests that human ancestors lost their body hair approximately 3.3 million years ago. Most mammals have light skin that is covered by fur, and biologists believe that human ancestors started out this way also. Dark skin probably evolved after humans lost their body fur, because the naked skin was vulnerable to harsh African UV radiation. Therefore, evidence of when human skin darkened has been used to date the loss of human body hair, assuming that the dark skin would not have been needed until after the fur was gone.