Counts of Ancestors

I put this graphic and explanation together to explain some anomalies in the data when I look at the number of ancestors I have, as compared to the number of ancestors that I should have compared to the number of people in the world, in Europe and in Norway during these times.

When considering how many ancestors one has, the answer appears to be mathematically infinite. In reality, you need to understand a number of practical factors when researching this. This graph helps illustrate the concepts. The graph has a number of illustrations:

The World Population is in red noting the world population from about year 1000 to the present. The yellow arrows note some significant events in Norway that affect population and genealogy studies. Specifically:
- The Viking Age which ran from about 800 A.D. to about 1200 A.D. During this time, the Vikings were widely traveled and some picked up wives from other geographic regions. If you look in this genealogy, you'll find Viking kings and their children intermarried into much of Northern Europe, the British Isles and all the way south to Spain, Portugal, and Italy as well as east to Kiev in the Ukraine (a trading route to the Constantinople or Byzantium, as they called it ). My "Norwegian" ancestry at this time is much broader than Norway. It includes most of Europe, mostly the places I mentioned above. The royals are known, few commoners are known during this period.
- The Black Plague was a significant event in Europe, much of in in southern Norway. Notice the dip in world population, even though the event was localized in Europe.
- The Reformation was a significant event in world history. In Norway, for genealogists, it signifies a time before which many of the common church records disappeared. The records were destroyed or taken by the priests that were expelled (or killed) as the churches were converted.
- Immigration from Norway took place from the 1800's to early 1900s as the population grew and unoccupied farmland was unavailable.
Norway Population is in green. It is a sliver of information on the chart since the population in proportion to the world is a very small percentage.
Ancestors are a calculated figure which assumes that each person has two parents (Duh!), and each generation spans about 30 years on average. One way to look at this brown filled curve is to think of it as how many of your ancestors were born after a certain year. None of my ancestors were born after 1930, 2 were born after 1900, 4 were born after 1870, etc.

The rest is explained below.

The world population in the last thousand years has grown roughly exponentially to it’s current count of about 4.2 Billion (2002). The population of Norway is about 4 million, just a blip at the bottom of the chart.

In the year 1000, it is estimated by most scholars that the world population was about 225 million. Norway had about 200,000, but that is not even sure, it may have been far less. In any case, the population of Norway is about one tenth of one percent of the world, for the last thousand years according to my research..

Mathematically, your ancestors double in count every generation…2 parents, 4 grandparents, 8 great grandparents, etc. 30 generations would yield over 2 billion 31st grandparents (2³⁰ = 2,147,483,648).

Obviously there is a conflict here. How can one have two billion ancestors in a population of 200 million, one tenth of the possibility, and much less when you consider that we are researching a population of limited travel [assuming that most of the population didn't travel, clearly the vikings were well traveled at that period of time]…we are researching a population of a few hundred thousand n all of Europe at most.

There are a few implications in this observation:

1)we are related to the same people in multiple ways. In the year 1000, you may have descended from a few thousands of couples rather than millions. The smaller the area of your origin (i.e., Norway), the more likely this is. Someone with a Chinese Father and Swedish Mother has a more likelihood of diversity, of course. In my case, the origins of my people point to southern Norway.

2)The farther back we go, the more likely we are related to other Norwegians. As 30th generation descendants, we are likely related through these common ancestors.

2 billion ancestors out of a population of 200 million means we have a good chance of being related to everyone at that time. Since the population of the Nordic areas is closer to 100,000 (about 50,000 are men). Having a 31st generation ancestor (one of 1 billion men), in a population of 50,000 means that there are 20,000 chances (1Billion divided by 50 thousand) to be related to a specific ancestor at least once.

Said in a different way, the probability of being related to any one person in the Scandinavia area in the year 1000 is about one chance in 50,000. You have 1 billion chances to be related at least once.

Some papers have suggested that in 30 generations, you are likely to be descended from 25,000 unique people, not billions. That would imply that each unique person is related to you in 40,000 different ways.

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This chart shows another interesting observation. The world population takes a dip in the 1300s. This coincides with the black plague in Europe, which wiped out up to 1/3 of the population in some areas. In Norway, it wiped out whole farms, leaving them empty for hundreds of years in some cases.

How Many Ancestors do I have, if I have Norwegian Ancestry ?...