DNA: The Extraction Process

The extraction process of DNA found in ancient human remains contains three distinct components: the preparation of the fossilized materials for extraction; the extraction of the ancient human remains using specific chemical materials; and the separation of DNA.

The first step of the extraction of DNA in ancient human remains is the powdering of bone material. This step also includes the incubation of the human remains located in an archaeological dig, in order to protect the remains from damage during the extraction of genetic materials.

Next, DNA is extracted using phenol-chloroform; phenol-chloroform is a liquid-liquid form of extraction method used in archaeology in order to purify DNA whose quality has been compromised by proteins. DNA may also be dialyzed against an ethylenediaminetetraacetic acid (EDTA), a crystalline acid with strong chelating properties and Tris Hydrochloride (Tris-HCl). This helps to purify DNA, creating a buffered solution, in order to separate DNA from foreign substances accumulated over time, which can affect DNA analysis.

After the extraction of DNA is complete, the aqueous phase of the process is undertaken. This stage separates DNA and purifies it. This procession of separation and purification can be performed using such materials as glass-milk or silica suspension.

Part of the extraction process is a form of DNA analysis known as Polymerase Chain Reaction (PCR) testing, which creates millions of identical copies of DNA from a biological sample. This DNA amplification allows for the analysis of DNA samples that are as small as a few skin cells. However, this type of DNA testing requires that samples not be contaminated with other biological materials during the identification, collection and preservation of samples. As such, during the extraction of ancient human remains, a variety of factors can affect the quality of DNA. This includes environmental degradation and the degradation of the sample itself, due to the oxidative process. These changes can affect the composition of DNA, making it challenging for archaeologists to analyze the DNA of human remains.

There are three basic results expected from the process of archaeological DNA extraction. These three results are:

• No DNA
• DNA that is fluffy in appearance. This means that the DNA has been sheared during the extraction process; however, in this case, it is still possible to analyze whether DNA is present or not
• DNA that appears in its original form, as long, narrow threads