Hey you! I mean whoever is reading this, did you know that we all belong to one family? The study which shows it, is more interesting and relevant in this fate filled world. Atleast this study comes close to prove that all of us have ancestors of every color and creed. Every Palestinian suicide bomber has Jews in his past. Every Sunni Muslim in Iraq is descended from at least one Shiite. And every Klansman’s family has African roots.!

How can this be?

Ok turn on your math skills and read on…

It’s simple math. Every person has two parents, four grandparents and eight great-grandparents. Keep doubling back through the generations - 16, 32, 64, 128 - and within a few hundred years you have thousands of ancestors.

It’s nothing more than exponential growth combined with the facts of life. By the 15th century you’ve got a million ancestors. By the 13th you’ve got a billion. Sometime around the 9th century - just 40 generations ago - the number tops a trillion.

But wait. How could anybody - much less everybody - alive today have had a trillion ancestors living during the 9th century?

The answer is, they didn’t. Imagine there was a man living 1,200 years ago whose daughter was your mother’s 36th great-grandmother, and whose son was your father’s 36th great-grandfather. That would put him on two branches on your family tree, one on your mother’s side and one on your father’s.

In fact, most of the people who lived 1,200 years ago appear not twice, but thousands of times on our family trees, because there were only 200 million people on Earth back then. Simple division - a trillion divided by 200 million - shows that on average each person back then would appear 5,000 times on the family tree of every single individual living today.

But things are never average. Many of the people who were alive in the year 800 never had children; they don’t appear on anybody’s family tree. Meanwhile, more prolific members of society would show up many more than 5,000 times on a lot of people’s trees.

Keep going back in time, and there are fewer and fewer people available to put on more and more branches of the 6.5 billion family trees of people living today. It is mathematically inevitable that at some point, there will be a person who appears at least once on everybody’s tree.

But don’t stop there; keep going back. As the number of potential ancestors dwindles and the number of branches explodes there comes a time when every single person on Earth is an ancestor to all of us, except the ones who never had children or whose lines eventually died out.

And it wasn’t all that long ago. When you walk through an exhibit of Ancient Egyptian art from the time of the pyramids, everything there was very likely created by one of your ancestors - every statue, every hieroglyph, every gold necklace. If there is a mummy lying in the center of the room, that person was almost certainly your ancestor, too.

It means One ancestral link to another cultural group among your millions of forbears, and you share ancestors with everyone in that group. So everyone who reproduced with somebody who was born far from their own natal home - every sailor blown off course, every young man who set off to seek his fortune, every woman who left home with a trader from a foreign land - as long as they had children, they helped weave the tight web of brotherhood we all share.

Excerpts From : Roots of human family tree are shallow