In this article, I will discuss the qualities of hair. I will also bring up some of its applications in forensic science. It is a continuation of my Hair in Forensic Science article.
Fun fact: Hair can be straight, curly, or kinky, depending on the cross-section, which may be round, oval, or crescent-shaped.
Hair Growth
Terminology
Anagen: Hair that is actively growing; lasts up to 5 years.
Catagen: Hair that is not growing.
Telogen: Hair that is dead; ready to fall out. Lasts 2-6 months.
Length
Hair grows about 0.5 millimeters per day, which translates to 1 centimeter a month. This would be ½ inch per month.
The root
Human roots look different based on whether they have been forcibly removed or if they are telogen hair. Animal roots vary, but have a general spear shape.
DNA From Hair
The roots of your hair contain nuclear DNA. If the hair was forcibly removed, some follicular tissue containing DNA may be attached. However, the hair shaft contains abundant mitochondrial DNA, inherited only from the mother. Identification can be done using the DNA of relatives if no DNA from the body is available. This process, though usable, is more challenging and expensive than using nuclear DNA.
Hair And Forensic Science
When hair is collected during a forensic examination, it must be taken by everyone involved, including the victim of the crime, any possible suspects, and anyone who could have left their hair on the scene in general.
Hair toxicology comes in handy when providing information on an individual’s history of drug use or poisoning. Hair must be taken from different locations on the individual’s body when testing to get a fully accurate timeline.
Thank you to Geetha S. for editing this article!
