Wednesday, October 19, 2016
The largest study of genetic variation in the human Y chromosome has revealed that half of all western European men are descended from an individual male thought to have lived 4,000 years ago
The team of researchers believe that this man was one of the earliest people to rule Europe in the Bronze Age. The study also shows explosive rises in male population numbers between 55,000 and 4,000 years ago. Using data from the 1000 Genomes Project, the study analyses the sequence differences of 1,244 human Y chromosomes from 26 populations around the world. Analyzing the Y chromosome of modern men can help us discover the history of our ancestors. The Y chromosome, which is only passed from father to son, is linked to male characteristics and behaviors. The team of 42 researchers involved in the study used the data from the 1,244 Y chromosomes to build a tree that reveals how the men are related to one another genetically. All the men studied were proven to have descended from a single man who lived approximately 190,000 years ago. Lead author Dr Yali Xue from the Wellcome Trust Sanger Institute said that this pattern tells us that there was an explosive increase in the number of men carrying a certain type of Y chromosome, within just a few generations. They only observed this phenomenon in males, and only in a few groups of men. One of the scientists involved in the study, Dr Chris Tyler-Smith, said that genetics can't tell us why it happened but they know that a tiny number of elite males were controlling reproduction and dominating the population. With half of western Europe descending from just one man, there can only be speculations as to why these increases in population happened. The results reveal that the earliest explosions in population occurred 50,000-55,000 years ago, across Asia and Europe, and a later explosion occurred 15,000 years ago in the Americas. The researchers believe this increase in population may be due to the movement of humans out of Africa and settling in Europe and Asia, where there were plenty of resources allowing the population to thrive. The study states that there was a notable increase in the number of lineages outside Africa around 50,000-55,000 years ago, perhaps reflecting the geographical expansion and differentiation of Eurasian populations as they settled the vast expanse of these continents. Later explosions in population occurred between 4,000 and 8,000 years ago in sub-Saharan Africa, Western Europe, South Asia, and East Asia. The later population increases are thought to be explored by advances in technology. The best explanation is they may have resulted from advances in technology that could be controlled by small groups of men. Wheeled transport, metal working and organized warfare are all candidate explanations that can now be investigated further. The data used in this study was gathered from the 1000 Genomes Project, which ran between 2008 and 2015, creating the largest public catalogue of genetic variation in the human Y chromosome.