As our ancestors ventured out of eastern Africa, they branched off in diverse groups that crossed and recrossed the globe over tens of thousands of years. Some of their migrations can be traced through haplogroups, families of lineages that descend from a common ancestor. Your paternal haplogroup can reveal the path followed by the men of your paternal line.

275,000 years to just one man: the common ancestor of haplogroup A. Current evidence suggests he was one of thousands of men who lived in eastern Africa at the time. However, while his male-line descendants passed down their Y chromosomes generation after generation, the lineages from the other men died out. Over time his lineage alone gave rise to all other haplogroups that exist today.

For more than 100,000 years, your paternal-line ancestors gradually moved north, following available prey and resources as a shifting climate made new routes hospitable and sealed off others. Then, around 60,000 years ago, a small group ventured across the Red Sea and deeper into southwest Asia. Your ancestors were among these men, and the next step in their story is marked by the rise of haplogroup F-M89 in the Arabian Peninsula.

Passing through the Middle East, your paternal-line ancestors continued on to the steppes of Central Asia, vast grasslands stretching all the way from central Europe to the eastern edge of Asia. From its origin in the western steppes nearly 50,000 years ago, haplogroup K-M9 spread across most of the globe. In fact, nearly half of all paternal lineages outside of Africa are branches of haplogroup K.

The next step in your story can be to the common ancestor of haplogroup R, a man who likely lived in Central Asia between 30,000 and 35,000 years ago. The Ice Age was still in full swing, and for thousands of years his descendants roamed the vast steppes of the continent, where they hunted huge mammals like the mammoth.

Your ancestral path forked off again between 20,000 and 25,000 years ago in western Asia, at the beginning of the last great peak of the Ice Age. Massive glaciers covered northern Eurasia, but farther south in the Iranian Plateau your ancestors flourished. When the Ice Age finally gave way to our warmer climate nearly 11,500 years ago, a new era of migrations from the Middle East began and eventually carried haplogroup R-M343 across three continents.

Your paternal line stems from a branch of R-M343 called R-M269, one of the most prolific paternal lineages across western Eurasia. R-M269 arose roughly 10,000 years ago, as the people of the Fertile Crescent domesticated plants and animals for the first time. Around 8,000 years ago, the first farmers and herders began to push east into Central Asia and north into the Caucasus Mountains. Some of them eventually reached the steppes above the Black and Caspian Seas. There, they lived as pastoral nomads, herding cattle and sheep across the grasslands, while their neighbors to the south developed yet another crucial technology in human history: bronze smelting. As bronze tools and weaponry spread north, a new steppe culture called the Yamnaya was born.

Around 5,000 years ago, perhaps triggered by a cold spell that made it difficult to feed their herds, Yamnaya men spilled east across Siberia and down into Central Asia. To the west, they pushed down into the Balkans and to central Europe, where they sought new pastures for their herds and metal deposits to support burgeoning Bronze Age commerce. Over time, their descendants spread from central Europe to the Atlantic coast, establishing new trade routes and an unprecedented level of cultural contact and exchange in western Europe.The men from the steppes also outcompeted the local men as they went; their success is demonstrated in the overwhelming dominance of the R-M269 lineage in Europe. Over 80% of men in Ireland and Wales carry the haplogroup, as do over 60% of men along the Atlantic Coast from Spain to France. The frequency of R-M269 gradually decreases to the east, falling to about 30% in Germany, 20% in Poland, and 10-15% in Greece and Turkey. The haplogroup connects all these men to still others in the Iranian Plateau and Central Asia, where between 5 and 10% of men also bear the lineage.

The spread of haplogroup R-M269 in northern Ireland and Scotland was likely aided by men like Niall of the Nine Hostages. Perhaps more myth than man, Niall of the Nine Hostages is said to have been a King of Tara in northwestern Ireland in the late 4th century C.E. His name comes from a tale of nine hostages that he held from the regions he ruled over. Though the legendary stories of his life may have been invented hundreds of years after he died, genetic evidence suggests that the Uí Néill dynasty, whose name means “descendants of Niall,” did in fact trace back to just one man who bore a branch of haplogroup R-M269.

The Uí Néill ruled to various degrees as kings of Ireland from the 7th to the 11th century C.E. In the highly patriarchal society of medieval Ireland, their status allowed them to have outsized numbers of children and spread their paternal lineage each generation. In fact, researchers have estimated that between 2 and 3 million men with roots in north-west Ireland are paternal-line descendants of Niall.