Skip to main content

Genetic Genealogy

Recently, my five years old boy asked me the question I knew it would eventually come. The very question all parents are inevitably facing with, when the right time comes. With my son it came in the most simplest form: "What is God?" popped occasionally after tons of OMGs he heard everywhere in his realm of cartoons, video games, YouTube channels and TV shows. I wasn't prepared completely. I mean I had pretty good idea of how to explain mythical phenomenons, unknown and unexplainable tales and the very concept of belief, but I didn't know how to do it without destroying Santa Claus, Easter Bunny and other fairy tales he enjoys every year. To me, it's much too early for that age in life. It would only add disappointment and confusion and its better to leave it for little later. So I performed good and old evasive maneuvers and in a couple of curves succeeded in changing the topic and postponing the inevitable for the next time which will come probably sooner than I think. The truth is, while it is not too difficult to explain the absence of God with simple Occam's razor principle, it is extremely hard to comprehend why so many people live in their world of prayers, worshiping the divine and believing in wide variety of religious stories.

Gene -> DNA -> Chromosome -> Cell*

To be honest whether or not God(s) is responsible for the very creation of life as we know it or it came after a long period of evolutionary 'tries and errors' one thing is for sure. Who ever the creator is, today we know great deal of how the life laboratory works and almost completely understand the very basic of how one live entity grows from the stage of being small seed (or two of them to be precise for many species) to fully formed individual. It's all written in the biggest molecule out there located in every single living cell. No matter if you are a virus, small bacteria, tree, ugly fly or any kind of mammal how you will look like and what will be your capacity to dazzle, it is all written in genes of your DNA molecule. To put it simple, one gene, or group of them are responsible for one property of you. They are virtually responsible for the way you are smiling, how you walk, why your hair is curly and blonde, how intelligent you are, how tall you are, why you love romantic movies and hate science fiction... They even define you to be either religious or skeptic, explorer or indigenous, emotional or psychopath... Basically everything that defines a personality. You can't escape from what you are as it is simply carved in the stone and irretrievably combined in your DNA sequence.

But how does it work really? You probably heard that human genetics are only couple of percent different to, for example, genetics of chimps, while the neanderthals differ in less than one percent. In human genetics, one parent is providing 23 chromosomes that are paired with other parent's and stored in our cells in total of 46. Chromosome sequencing counted sum of 32.185 genes responsible for unique appearance of each person. There are no two identical individuals, even identical twins differs on genetic level providing for example different fingerprints among hundreds of other genetic differences they have due to mutations in genes in their early development.

Map of Human Migration**

Contrary to all those differences between individuals, genetic genealogy, on the other hand, deals with similarities and identical sequences in human genome, trying to classify humans in their groups of origin. This scientific effort is providing better understanding of human migrations from the point when everything started for all of us back then in Africa. Many genealogy surveys are performing DNA testing for this purpose and after less than a decade of mass analyses DNA material and thousands of specimens, dozen of haplogroups (geographic areas or migrational paths occupied with people with same or similar sequences in particular genes) are identified. The evolution of humans depends on one single thing - mutations in genes or errors made in human genome due to environmental and other factors in long history of human migrations. Homo sapiens lived entirely in Africa 150.000 years ago and started migrating out approximately 70.000 years ago. This process is considered finished only 2.000 years ago when the last habitable island in Pacific was occupied. Along the way our ancestors changed according to the conditions of the area they encountered and evolutionary speaking divided into different races and groups. The research so far gave us very interesting results. Probably the most valuable fact given is that we all share the same family lineage. So far, among all tested DNA samples, it is not yet identified a sample with different rooted ancestors, both male and female. This hints that all people on Earth are having the same ancestors, scientific Adam and Eve, or to be precise 'Y-chromosomal' Adam and 'Mitochondrial' Eve.

In other words, everyone is related and basically if we had the data of all people in the world ever lived we could be able to create one giant family tree started with mentioned Adam and Eve. Even though they didn't know each other and lived separately by maybe 100.000 years, those two lineages are now the only one survived in time. At least until we don't find different data in Y-DNA and mtDNA tests and find more ancestor roots. Only to be fair, after all the testings so far it seems that even if we find any, they would only represented the side paths and small groups of humans sharing this hypothetical lineage(s). But how exactly it is possible to trace down your ancestors by analyzing the DNA code? The goal is to identify sequences in DNA that are in a way "immune" to mutations and passed from generations to generations almost unchangeable over time. There are sequences like that in the male sex Y-chromosome passed only by fathers line. More than 100 of sequences and their repetitions within the chromosome are identified over years and today used in searching for match for most recent common ancestor when two samples are compared. Those sequences in laboratory are called markers and as many markers are used for comparison the more precise the result could be, meaning you would be able to find more recent common ancestor. Same is with maternal lineage test, only in this case X-chromosome is useless due to severe changes over time and instead mitochondrial DNA (mtDNA) is used as this is passed by female ancestor in almost unchanged form. Similar to the Y-DNA test markers are compared only with a difference that this time it is not number of repetitions of sequences that are searching for but instead predicted changes or rare mutations in DNA recombination happening over time. The same procedure can be used for testing Y-DNA as well. Combination of this two testing types and comparing the results with sample database provide matches in both recent and ancient ancestries and predict appropriate haplogroup for the specimen along with the list of many relatives who already tested and found in the database.

Haplogroup I (Y-DNA) distribution

You probably noticed that I am not trying to include too much scientific data and terms. If you are eager to dive deeper into this extremely interesting research please find links and follow up stories I included at the end of the post. Furthermore I am not expert in this field, just another reader following the research for more exiting discoveries and possible breakthroughs and not only in genetic genealogy but in DNA general sequencing as well. With courtesy of Beth Perry Steger, my dear Facebook friend, I own a NG's Genographic testing kit, the project with probably the biggest database of tested users counting more than half a million users. Unfortunately, due to Serbian law policy that forbids sending any kind of biological samples via any kind of mail services I am still waiting for the opportunity to do this abroad but nevertheless there are only couple of Haplogroups I can belong to and the biggest probability is the Haplogroup I (M170) where almost one third of population of Serbs are predicted to origin from. However, there are couple of more candidates for this region of the world, if we exclude possible surprises and unknown data happened in history of my family. Long ago I started to fill out our family tree online and only have partial data for generations 5 and above which is too small data specimen to conclude anything valuable. I am sure I will know more in following years and that this post thread dedicated to genetics will get its successor.

Finally and probably completely unrelated to genealogy described in this post which is more anthropological study and not used for medical purposes, it would be unfair, to say the least, not to mention the large percent of noncoding DNA or "junk DNA" portion of human genome. More than 50% of the double helix is still not fully understood. It is determined that this part of DNA is not encoding protein sequences like those genes we mentioned earlier. It seems that big part of this DNA sequences don't have any known biological function and only recently some new theories and studies indicate that they are very active and serve in regulation or fine tuning of proteins. Difference in protein regulations and molecules might be responsible for different reaction of people to the same disease. It is not clear why, for example, identical twins react different to some infections or diseases to the case that in same environments one twin can be more immune to same disease comparing to his sibling.

Anyway, entire DNA research is still young science and I am sure more and more discoveries are still awaiting in near future and to make sure we better understand what are scientists dealing with, just try to comprehend the size of this molecule. I found the fact that one single gram of DNA can hold 700 terabytes of data while one state of the art personal notebook today contains less than one terabyte of internal memory. Imagine what can be stored inside. If even a tiny portion of junk DNA is really junk we might learn how to use it to store files inside. One day instead of magnetic hard drives you might have a personal computer that connects to cockroaches carrying your personal data.

Guide to Finding the Best DNA Ancestry Test

* Cell division

Image follow up stories


© 2020 Milan's Public Journal