The genome is the set of genetic material that we inherited from our parents and is usually analyzed in three areas because each tells us complementary stories about the ancestors of a person:
- Autosomal chromosomes
- Sex chromosomes
- Mitochondrial DNA
The 22 chromosomes called autosomes are in pairs, since we inherit one copy of the mother and another of the father. Therefore, the genetic profile derived from autosomes is a combination of our ancestors, both maternal and paternal, and is characterized by allowing the mixture of multiple ancestral lineages that go back thousands of years. This mixture is one of the great sources of human diversity that we observe today.
There are two other parts of the genome that are inherited without mixing between lineages. They are mitochondrial DNA which is inherited exclusively through the mother and from the Y chromosome that is inherited through the paternal route, in the case of males. This genetic material also accumulates changes (mutations) over time and according to the combination of these mutations each person is assigned a haplogroup. However, by not mixing with the genetic material of other ancestors, one can trace the geographical origin of the mutations and thus trace the migratory path of the maternal and paternal ancestors of each person since the human species appeared. In this sense we are all mutants and we are all migrants.
Where do humans come from?
All humans share a common origin somewhere in southeastern Africa where our species originated approximately 200 thousand years ago. From a common ancestor, which all primates (including humans, chimpanzees, gorillas, orangutans, etc.) share, our species began to differentiate and acquired anatomical and cognitive characteristics that distinguish it from the rest. This group is known as the population of modern humans. For thousands of years modern humans remained in Africa, but about 70 thousand years ago a group left that continent to search for new lands and that is how the world began to be populated. Anthropological evidence suggests that the exit from Africa occurred in the Middle East and that, following a coastal route, humans reached Southeast Asia and even Australia and Melanesia approximately 50-60 thousand years ago.
Modern humans, when leaving Africa, went to Europe and to Central and East Asia, where they met the Neanderthals. By this time, the Neanderthals had left Africa and had inhabited much of Eurasia for 400,000 years. The last great migration occurred approximately 15-20 thousand years ago when a group of humans crossed from Siberia through the Bering Strait to the American continent and populated the whole continent from North to South until arriving in Patagonia.
What is genetic ancestry?
During this journey of great migrations, many generations passed and in each of them, mutations have occurred in our genetic material that are transmitted to the children, who in turn transmit new mutations to their descendants and so on. It has been estimated that approximately 60 new mutations appear in each individual in each generation. This series of changes have made human populations different and is one of the main sources of diversity that we observe today. These genetic changes have been recorded in the DNA sequence of each individual and by comparing a large number of individuals we can identify the origin of each one of their mutations. You can also detect mixing events and calculate the proportions in which each ancestral population contributes to the genetic profile of each individual. It is this concept that we call genetic ancestry.
Latin America is a region where a large amount of genetic mixing has occurred in the last 500 years due to the contact of populations from different continents that have been isolated for thousands of years after regions of the world and therefore genetically differentiated. The greatest genetic contributions to the Latin American population come from indigenous populations in the Americas, which in turn harbor a great ethnic, linguistic and archaeological diversity, as well as European and African populations. However, there is also an important presence of ancestral components of very diverse origins given the intense migration that accompanied the process of colonization in Mexico, in the rest of Latin America and in other regions of the world, which in turn have become much more connected. easily in the modern era where intercontinental travel is more frequent and simple.
That's how now with genetic tools you can discover your ancestral history and know in detail the roots that make up the mosaic of diversity that you carry inside.
What implications does knowing your genetic ancestry have?
The family history told by genealogical records generally goes back a few generations. In most cases, we lose track beyond grandparents or great grandparents. However, the DNA keeps a historical record of all the ancestors that have contributed to the mix that makes each person unique. Although we do not know who were specifically these ancestors, we can identify their origin through genetic similarities between your sample and the descendants of ancestral populations around the world, which we use as a reference. In this way, we can calculate the proportion of each of these ancestral components in your DNA, that is, estimate your genetic ancestry.
Knowing these genetic roots can help us to recover stories that otherwise have left no record. This is more common in regions with a high degree of miscegenation such as Mexico and Latin America, where the ancestors of the current population came from distant regions of the world and whose registration has been diluted in the generalized notion that the mixture can erase our estate. However, with these high resolution genetic analyzes we can identify the origins of each person within their indigenous roots in America, Europe, Africa or any other region of the world. For example, most Mexicans have an indigenous contribution and now, thanks to our detailed reference panel, we can know which ancestral populations we have inherited.
It is very important to distinguish that the populations used in this analysis are only a reference to approximate your DNA sample to the ancestral group with greater similarity and we have made an effort to make this approximation as accurate as possible. However, it is virtually impossible to have representation of all the possible ancestral populations of the world, so that an allocation of a certain percentage to a specific ancestral group (for example Pima) can also be compatible with other similar ancestors of the same region (Like Yaqui or Mayo or some other indigenous group from Northern Mexico that is not represented in our reference panel). In this way, genetic ancestry is also a very powerful tool to contribute to the identity of individuals and populations. However, no percentage of ancestry defines membership or identification with a particular ethnic group nor is the role of any genetic test to determine it. We believe that this self-determination responds to multiple social, linguistic and cultural factors and that it is an individual decision of each person. With this test we simply aim to offer a tool to bring the advances of genomic sciences to the general public and allow everyone to know more about their own roots and the diversity that makes us unique.
Behind the genetic test of SOMOS is a team of experts in genomics of human populations with wide international recognition ...
Genetic information contained in the genome can tell us so much more aspects besides ancestry, which contribute to each person being unique. For example, it is possible to assess the risk to certain diseases or traits ...
How does it work
It all starts in the cells that can be recovered from your saliva sample and that contain your genetic information. The first step of our analysis is to extract and isolate the DNA from your cells. The next step is to amplify the molecules...