The absolute number one point that must be understood about ancestral trees and genealogy is that the results have nothing to do with feelings or family. Step-relatives and adoptions may be loved and adored, but have nothing at all to do with matters of the blood. Ancestral trees are one hundred percent about which strapping buck shagged which fair maid in the past to build the unique combination of genes that is you.
The number of people involved in the creation of “you” is astounding.
- two parents
- four grandparents
- eight great-grandparents
- 16 great-great-grandparents
- and so on (32, 64, 128, 256, 512, 1024, 2048, 4096….)
Clearly a binary progression starting with you and heading into the past towards the time of creation of the species. Now I absolutely do not want to get into a discussion of the age of our species – much less one regarding the age of our planet. Regardless of whether you are a creationist or a “big-banger”, one thing that is universally agreed upon is that human beings existed and were breeding on this planet 6,000 years ago. So the next question becomes… How many generations can “fit” into 6,000 years?
Many ancestral trees on the internet seem to assume (in lieu of concrete birth and death years) a thirty year span between average generations. By extension, four generations should span 120 years, and 40 generations should take 1,200 years. 6,000 years therefore corresponds to 200 generations.
But just how many people “is” 200 generations? Time for Math. Going back to the binary progression idea, we know that one generation change can be represented by two parents. This can be expressed more “mathematically” via 2**(one generation) = (two parents). Going onward, 2**(two generations) = (four grandparents) followed by 2**(three generations) = (eight great-grandparents). But what number is represented by 2**(200 generations)? Answer, a whole lot. But even the actual huge number behind “a lot” is not really close. 2**200 is actually only the number of great-to-the-197th-grandparents each individual has. When counting individual ancestors in a family tree, one also has to account for 2**199 great-to-the-196th-grandparents, 2*198 great-to-the-195th-grandparents, and so on.
The total number of ancestors among 200 generations is expressed as (2**201))-1. The value is astounding: 3213876088517980551083924184682325205044405987565585670602751.
This theoretical value is several tens of orders of magnitude above the number of humans who have ever existed. Clearly, something else is going on to have made this possible. The answer – shared ancestors.
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