Who's Counting: Jesus' Descendants

June 3, 2006 -- -- This month's Who's Counting briefly examines three very different stories in the news. The first concerns Dan Brown's "The Da Vinci Code" and the movie of the same name. The novel is based on the premise that Jesus married and had children, and that a direct descendant of his is alive today.

Probability theory tells us, however, that if Jesus had any children, his biological line would almost certainly have either died out after relatively few generations, or else would have grown exponentially so that many millions of people alive today would be direct descendants of Jesus.

Of course, this is not a special trait of Jesus' descendants. If Julius Caesar's children and their descendants had not died out, then many millions of people alive today could claim themselves Caesar's descendants. The same can be said of the evil Caligula and of countless anonymous people living 2000 years ago. It is not impossible to have just a few descendants after 2000 years, but the likelihood is less than minuscule.

The research behind these conclusions, growing out of a subdiscipline of probability theory known as branching theory, is part of the work of Joseph Chang, a Yale statistician, and Steve Olson, author of "Mapping Human History: Genes, Race, and Our Common Origins."

Going back another millennium, we can state something even more astonishing. If anyone alive in 1000 B.C. has any present day descendants, then we would all be among them. That is, we are descended from all the Europeans, Asians, Africans and others who lived 3,000 years ago and have descendants living today.

Consider the implications for future generations. If you have children and if your biological line doesn't die out, then every human being on earth 2,000 or 3,000 years from now would be your direct descendant.

Getting back to "The Da Vinci Code," we can conclude that if the heroine of the book were indeed descended from Jesus, then she would share that status with many millions if not billions of other people as well. This makes the book's plot even harder to swallow, but then probability was never much of a match for fiction or Hollywood.