Brad Ideas - Random Ideas - Comments

It's harder over the long distances

brad — Sat, 23 Jul 2011 10:09:39 -0700

The numbers are huge, but the amount of travel and interbreeding of the regions was much less until the 19th century and in the 20th century the borders were vastly lowered to interbreeding. I say everybody is your cousin within the breeding community you came from but it takes a lot of detail to track the more dispersed groups.

Lets narrow things down...

Anonymous — Sat, 23 Jul 2011 07:50:55 -0700

Lets say just Asians, Europeans, Africans and other non-isolated populations can be included. Judging from my own intuition and other factors on the field I have contacted, could 16th cousins still hold? I mean, that far back, each couple could potentially have 4294967296 people descended from them. Of course, due to inbreeding, ancestors are shared thus increasing the odds of anyone being descended from them. So lets just say Asians, Europeans and Africans. How would that turn out?

Actually...

Anonymous — Tue, 07 Jun 2011 08:11:47 -0700

I actually took this up with some experts. They concluded that finding common ancestors for people of European, Asian and African ancestry would be within 300-500 years. However, this does not apply to isolated Native American tribes, Oceanic peoples and Australian aborigines. In other words, finding ancestors within that time frame would strictly apply to people of Old World descent, not including the completely isolated peoples.

Family tree calculations

Jim — Sun, 08 May 2011 13:40:00 -0700

If there was no inbreeding by the time you go back 28 generations ( around 1,000 AD)
You have 268,435,456 Ancestors - World Population was around 275,000,000.
My Mom's side & Dad's side of the tree meet with Alice Montagu, Joan Beaufort just to name 2 common ancestors of both trees & there are a lot more. I have SEVERAL places where a Ancestor has 2 or more children - they split off but come back together in a couple generations. I can get back to Noah through Shem & Japheth from either side of the family- PROVING it is the hard part.

The world

brad — Tue, 22 Mar 2011 16:38:32 -0700

Everybody in the world would be related if we interbred with people in other countries and tribes the way we do today. However, prior to 500 years ago, nobody interbred between the Americas and Eurasia/Africa, and Australia was also isolated. Travel was also slow within Eurasia/Africa.

However, there has been a lot of interbreeding in the past 5,000 years, so there are fewer and fewer “pureblood” people left on the planet. Soon they will all be gone unless they take tremendous effort.

I'm WAAAAY Confused!

Anonymous — Tue, 22 Mar 2011 14:22:28 -0700

Wasn't this article supposed to show how related everyone in the world is or does this only include people of European descent"

I understand, sort of...

Anonymous — Thu, 10 Mar 2011 16:18:11 -0800

So only Europeans are 16th cousins?

Sorry

brad — Thu, 10 Mar 2011 15:26:27 -0800

I don’t understand this question. Because of geographic isolation, Europeans may not share with Chinese, necessarily. They will share with other Europeans. The math in this post simply says that if I have a million ancestors from Europe and you have a million ancestors from Europe, the odds that there is nobody in both sets are very, very low. If I have a million ancestors from Europe and you have a million from China, it’s more possible that they two sets don’t overlap.

My reply

Anonymous — Thu, 10 Mar 2011 14:58:41 -0800

But if you share at least on 16th G-G-G grandparent with any Chinese, wouldn't it seem likely that least one of those common ancestors are Chinese?

Your ancestors

brad — Mon, 07 Mar 2011 22:14:11 -0800

Because as you go further back in time, people moved around less and bred around less, things don’t branch out geographically as much as they would with today’s patterns. Again, going back 500 years you have a million ancestor slots, and due to overlap, a smaller number of ancestors. There were Chinese who made it to Europe 500 years ago and who were breeding with Europeans. It is not certain you have some of them in your ancestry but certainly possible if your general ancestry is European.

Fewer Americans came to Europe, none before 500 years ago, and I would guess they bred less.

What about ancestors

Anonymous — Mon, 07 Mar 2011 19:15:33 -0800

I just had a curious thought. Could this counter-intuitive phenomenon, the Birthday Paradox, be used to estimate unsuspected ancestry? Like, could it be used to say that a European could have ancestors among the Medieval Chinese Population? How likely is it and how long in terms of generations into the past would it take? What do you think about that? Is there any merit to it?

How far back do you want to go

brad — Thu, 24 Feb 2011 09:54:53 -0800

Once you go back far enough so you have millions of ancestors at that level, then you are going to be descended from every type of person in the regions your ancestors came form. Some lords, lots of peasants — just as in the population then, there were a few lords and lots of peasants. You may get a slightly larger representation of lords and rich people because they could afford to have more families. Some lords were notorious for also siring lots of children outside wedlock, and thus are over-represented compared to the ordinary individual.

Since populations used to keep much more closely together in the middle ages (today we interbreed very freely by comparison) you will have fewer ancestors outside your ethnic groups, but it would be very rare to have none if you go back far enough.

And generally, within any given geographic region, go back 1K to 2K years and you are descended from everybody who lived then, unless that person’s line died out quickly (ie. they had no children, or grandchildren.) Once a person gets a line going it’s pretty much impossible to keep it from mixing with all the other lines. The only thing that will do that is a huge geographic barrier. (ie. the population of the Americas was kept isolated from Eurasia for 10,000 years until 1492.)

What are the odds?

Anonymous — Thu, 24 Feb 2011 03:58:17 -0800

What does anybody think about the odds of being descended from any given person living back generations back? Like, for example, what are the odds of the ancestor of being a Lord, a Samurai, a peasant or a Tribal warrior? What does anyone think? My own thoughts would be to divide the population of the world by the number of ancestors to determine some basic odds. Well, please give me some feedback.

Depends on the person

brad — Tue, 22 Feb 2011 15:24:26 -0800

But to go back 500 years to 1511, say, that’s going to be 20 or so generations. Your family tree 20 generations back has one million slots, but due to re-forking (distant inbreeding) many of those ancestors will appear in many slots, especially if you came from closely knit tribes or villages in some sections of your tree.

So if you imagine you have 250,000 unique ancestors from that period — and I don’t really know what the right re-blending number is — you would want to look at the populations of the regions and ethnic groups from which you came, and you could calculate the odds of any one member of such a group being an ancestor. But many of us are mixes of ethnic groups, so only some of your tree is going to qualify.

If you are truly “purebred” and your ethnic group had a population of 10 million 500 years ago, and you have 250K ancestors within it, then the odds are 1 in 40 that any given one is your ancestor. However, the more purebred you are, the more inbreeding, so in fact the odds are poorer. I may be underestimating the inbreeding by a lot here.

What are the odds?

Anonymous — Tue, 22 Feb 2011 12:28:34 -0800

What do any of you think about the odds of being descended from anyone in any given point in time? I mean, how likely is it being descended from a person in the 16th century?