History Of Dna Analysis
DNA first started to play a role in the 1800s when a child was born and didn't have either parent's eye color. At the time it was believed that children had a mix of their mother and father's traits. This lead to the eye color paternity theory, which was based on that mixed trait belief. In 1865, the father of genetics Gregor Mendal came up with a foundation for which inheritance and genetics determined a child's traits. Mendal's laws would become the foundation for modern DNA testing.
When scientist discovered the four different blood types in the early 1900s it lead to more advancements in DNA testing. In the 1920s the genetic component of blood typing was discovered and scientist realized that they could determine a child's blood type based on the blood type of their parents. This information led to paternity testing based on blood typing. However, this was a flawed system because it only determined if blood types matched or were compatible. In other words, it narrowed down what blood type a child's parents could have, so in some cases it could eliminate a person, but not in all.
A decade after people started to use blood typing to determine paternity scientist discovered proteins in the blood that could uniquely identify a person. This is when serological testing was developed. Using serological testing scientist were able to determine the blood group of a child based on the blood group of their parents. However, like blood typing, this method of testing was not very accurate and only served to exclude certain people.
Progress kept rolling on and in the early 1950s a team of scientists in England discovered actual DNA. X-ray diffraction was used to analyze DNA molecules. The analysis determined that DNA was actually resembled a ladder with molecules being paired at the rungs of the ladder.
Two decades later in the 1970s scientist began tissue typing and discovered the HLA protein. Scientist found out the HLA protein was present everywhere in the body accept the red blood cell. They also determined that HLA was highest in concentration in white blood cells, and that there are different types of HLA that varied from person to person. HLA testing was able to determine paternity with an 80% accuracy.
DNA testing kept advancing through the 1980s and 1990s. In the 80s scientist discovered a technique for DNA testing called restriction fragment length polymorphism. This technique was the first genetic test to use actual DNA. The standard for DNA testing changed in 1990 when scientist began to use a new technique called polymerase chain reaction or PCR. This method produces quicker and more accurate results.