DNA has been the subject of exceptionally high interest to the public for the last three decades. It played a critical role in the famous trial of O.J. Simpson in 1995 and this trial and its absorbing TV coverage stimulated great interest among the general non-science community. Since then, almost every TV detective story plot involves forensic DNA.
As one of the very top ideas in popular scientific media, DNA is used to identify pathogens, identify biological remains in archeological digs, trace disease outbreaks and study human migration patterns. It is also used in diagnostics, new vaccine development and cancer therapy. As illustrated in the O.J. Simpson trial, DNA revolutionised crime scene analysis in many countries including New Zealand and provided decisive evidence in many local court cases involving violent offenders. The Crown Research Institute, ESR, provides the expert witnesses and conducts DNA analysis and manages DNA databases for the NZ Police. I served as a government appointed director on the board of ESR for several years.
At a family and an individual level, DNA is the basis of popular interest in www.ancestry.com and related genealogy services, as people seek to understand more about their distant forebears. There are some ethical concerns about private DNA data being made accessible by other parties with vested interests in ethnicity and health information.
But what is DNA? Deoxyribonucleic acid, or DNA, is a complex long-chain molecule that exists as a helical structure. The DNA contains all the information necessary to build and maintain an organism. All living things have DNA in their cells and this defines their form and function. It also serves as the primary unit of heredity in organisms of all types. When organisms reproduce, a portion of their DNA is passed onto their offspring, which ensures a degree of continuity from one generation to the next while at the same time as allowing for slight changes that contribute to the diversity of life.
All modern human beings (Homo sapiens) on the planet are 99.9% identical in their DNA make-up.
Neanderthals share 99.7% with modern humans but because of inter-breeding with early modern humans, we have retained a small proportion of their DNA. Chimpanzees share 98.8% DNA in common with humans. Pigs (98%), cats (90%), dogs (84%) and cows (80%) are also high on the DNA commonality list. In contrast, yeasts have 26% DNA commonality with humans. The link https://thednatests.com/ gives a more complete list of organisms and their commonality percentage.
As an example, Covid 19 testing depends primarily on detection of viral DNA while the identification of the variant type (e.g., Delta or Omicron) depends on the identification of the entire virus genome. The genome is the entire set of DNA instructions in the virus cell, which provides a distinctive fingerprint for each variant.
The small difference between the DNA of different individual humans (see above) incorporates significant information about an individual’s propensity to specific illnesses. An aspect of this field is the matching of specific medication to a patient’s individual DNA. This is an example of the emerging and future field of genetic medicine which is expected to benefit us all.