With 100 $ and one internet click you can find out the path your ancestors trod. How did people get to populate the world? Archeologists and paleoanthropologists tried to find out the answer to this question in the few traces they could find- the scattedred remains of our remote ancestors.[BR]However, the old towns and artifacts could only tell a fragmentary story. In the present, geneticians discoverd complete files of prehistoric migrations, written in our genes.Mutations of certain components of human DNA accumulated in sequences like layers in a geologic fault. DNA analysis helps researchers establish what was the path our ancestors trod. It costs 100 $,plus taxes and a click. By comaparing these sequences among populations of the globe and then by transposing them on a map, scientists revealed the sketch of paths trod by eary migrations, genetic traces left by our ancestors while they adventured out of Africa to colonise the world. Long lines have been drawn , intersected,each of them marking the passing of a distinct genetic line. Embracing the coast lines, the deserts and wandering on fields, these people roamed generations after generation, following the rythms of hunt and harvest. The progress seemed imperceptible on a generation scale, but at the end of 50000years, people occupied all the inhabitable contintents of Earth. In their way towards them they gave birth to diverse populations, we see today in the whole world. This fascinating odissey makes the study of a materialpublished by "National Geographic". DNA: It contains the whole information necessary to construct the human body. it is composed of long liniar sequences, named nucleotides.
There are 4 nucleotides which make the double heliocoidal DNA, distinguished by symbols. They are called the bricks of life, and their order and position encode the information in the DNA. Marker: A fragment from DNA, with a known position , useful in retracing specific genes and genetic diseases. It is known that neighbouring DNA fragments tend to be inherited , property that allows the use of markers in order to determin exactly the inherited pattern of a gene , that hasn't yet been identified. There are two important types of markers. Mutation: aleatory modification in DNA sequence,produced as result of a copying error during the cellular division. It can mean the replacement of only one necleotide by another, or the adding or erasing of a nucleotide. Mutations happen very rarely, but as the human genom has a great size (six milliards nucleotides), the children have about 50 mutations that distinguish them from their parents. Haplogroup: A group of branches that have in common a set of mutations specific to the members in the respective group.because Haplogroups are defined by mutational events that occur at a certain time and in acertain place in the history, they have features representative for the age and the amplitude of migrations which create the history of that period.