myDNAOrigin

The modern human (Homo sapiens) originated in Africa, the continent where we have spent most of our existence, some 200 000 – 300 000 years ago. It was only about 60 000 – 70 000 years ago that a small East African population migrated out-of-Africa, giving birth to all non-African populations. As genetic diversity continues to increase with time, so the greater genetic diversity within the much older African population can be better explained.

One group of the out-of-Africa migrants moved east, reaching India, Southeast Asia and finally Australia approximately 50 000 years ago.

Another group of out-of-Africa migrants moved to the Near East/Arabian Peninsula, and further split into two groups; one eventually reaching and settling in Europe about 45 000 years ago, and the other returning to the continent to settle in North Africa.

The populations that settled on the Asian continent eventually reached Siberia. Approximately 15 000 – 20 000 years ago they crossed the Bering Strait, reaching the American continent for the first time.

Ancient DNA studies showed that when the modern humans travelled out-of-Africa, they crossed paths with other human groups, namely Neanderthals and Denisovans. Hence, the genome of current European and Asian populations has approximately 2.3% of Neanderthal input; and the Southeast Asian population can have up to 4% of Denisovan input in their genomes. Interestingly, the Sub-Saharan African population does not have any input of either Neanderthal or Denisovan in their genomes, as these groups were never present in Africa.

Given the origin and migration of our species, human populations have primarily been organised into three large ancestral groups: African (Sub-Saharan Africa), Asian (more precisely East Asia) and Eurasian (not only Europe, but related by ancestry, Southwest Asia, North Africa and to some extent Central Asia).

There are gradients of genetic diversity between the human populations – some DNA variants are more frequent in certain regions than in others. Thus, as we analyse millions of DNA variants at the same time, we acquire an excellent resolution in identifying the origin of an individual based on their specific genetic profile.

DNA is passed from parent to offspring, from generation to generation, and has been doing so for hundreds of thousands of years. Therefore, your DNA contains bits of information from all your ancestors, serving as a map that can be used to determine where your predecessors originated.

• The DNA stored inside your autosomal chromosomes (DNA)
• The DNA stored inside your mitochondria (mtDNA)
• The male Y chromosome

Humans have 23 pairs of chromosomes including the sex chromosomes which determine the male (XY) or female (XX) gender. The Y chromosome only exists in males, passed from father to son, generation after generation. For males, we can therefore analyse the genetic information in your Y chromosome to discover your paternal ancestry (from your father’s side of the family). Paternal ancestry is defined by a haplo group: a group of individuals who share the same genetic variation and have the same paternal ancestor.

Both males and females have mtDNA, but it is only passed on by female parents to offspring. A mother will pass her mtDNA on to all of her daughters and all of her sons. The mtDNA can therefore be analysed to find out your maternal ancestry (from your mother’s side of the family). Maternal ancestry is also defined by a haplo group, being a group of individuals who share the same genetic variation and have the same maternal ancestor.

Founded in 2008, DNAlysis continues to pioneer personalised medicine services here in South Africa and abroad. Recognised as a leader in the industry, hundreds of doctors and healthcare practitioners around the world have come to rely on the DNAlysis team for support and training, while our tests have gained a reputation for being clinically relevant and scientifically robust. Our ISO-accredited laboratories in Johannesburg and Helsinki process more than 2000 DNA samples per month, reporting on Nutrigenomics, Pharmacogenomics, Ancestry and Risk Screening.

As one of South Africa’s premier genetic testing laboratories, DNAlysis offers an innovative approach to genetic testing. Our industry-leading methods provide healthcare practitioners and patients with uniquely personalised treatments; and enables a more precise, predictable and preventive approach to healthcare.

Our network of highly trained healthcare practitioners use our range of DNA tests to gain a greater understanding about possible lifestyle, supplement and nutritional interventions that will assist their clients with a number of genetic related health concerns.