| Suppose a dead body was found and crime scene | | | | not human in origin. Another thing in the medulla that |
| investigators are called out to the scene to | | | | forensic scientists look for is whether the medulla |
| investigate. One of the few things they find left | | | | looks solid and continuous, or fragmented. Such |
| behind on the victim or in the back seat of a car is | | | | characteristics can help the scientist determine the |
| human hair. | | | | species of origin. There are databases of hair types |
| What is so special about hair to the criminalists? In | | | | from various animals that help criminalists arrive at a |
| this article, I will discuss the anatomy of human hair | | | | match. |
| and what part of hair is the focus of a forensic | | | | - Cortex: External to the medulla is the cortex. It is |
| investigation. | | | | the largest part of the shaft and is the part that |
| Hair grows out of the skin from a hole containing | | | | contains pigment, the substance that gives hair its |
| highly specialized cells called the follicle. There are | | | | color. Pigment particles display a wide range of colors, |
| three things that make up the shaft of human hair. | | | | shapes, and distribution patterns. All of these |
| The forensic scientist can use any of these three | | | | characteristics help forensic scientists determine race, |
| things to find a match between hair taken from the | | | | match unknown to known hair, and identify origin of |
| victim and unknown hair taken from the back seat of | | | | hair. On the microscopic scale, forensic scientists take |
| a car. The makeup of hair resembles that of a yellow | | | | advantage of the pattern of air pockets and |
| No. 2 pencil that you used in school. From inside out, | | | | structures within the cortex to arrive at a match. |
| the medulla would be the lead, the cortex would be | | | | - Cuticle: The cuticle refers to the layer of cells that |
| the wood, and the cuticle would be the yellow paint | | | | cover the external surface of the shaft and resemble |
| on the outside of the pencil. | | | | scales on a fish or maybe tiles on a roof. Forensic |
| - Medulla: The central part of the hair is called the | | | | scientists take advantage of the patterns found in |
| medulla which contains a slew of cells but looks as | | | | the cuticle to determine if hair is human and whether |
| though it is an empty or mud-filled central tube. The | | | | or not there is a match between this hair to another. |
| internal diameter of the "tube" with regard to the | | | | Small hairs can not escape the prying eyes of an |
| overall diameter of the hair is referred to as the | | | | expert forensic scientist. Finding a consistent pattern |
| medullary index. In human beings, the medullary index | | | | between unknown and known hair can bring crime |
| is measured out to be 0.3. What this means is that | | | | scene investigators one step closer to solving a |
| the medulla makes up 30% of the total diameter of | | | | crime. |
| the hair. In animals the medullary index is a bit larger | | | | The next time you watch your favorite CSI TV |
| than 0.5. If forensic scientists determine that hair | | | | show, you will have a better understanding of why |
| found in the back seat of a car has a medullary index | | | | hair is important in a criminal investigation. |
| greater than 0.5, they can conclude that the hair is | | | | |