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How Many Ancestors Do You Have?

My grandparent ancestors have been in America for around 270 years with 8 generations for my maternal and 9 for my paternal families. That makes the actual number around 25 years per generation. Our ancestors number more than a million in 20 generations with our 16th great-grandparents from roughly the year 1525 if none of them were related through more than one family. At 8 generations you have 254 ancestors in that generation. At 15 generations over 32,000 ancestors in that generation. At 21 generations you have over a million ancestors in that generation with a total of over 2 million total ancestors! Most of our ancestors would be related multiple times in the small farming communities and villages where they would have lived. I have found a number of instances in a few of my family lines which show many common ancestors on both sides of the family making spouses second and third cousins, rarely first cousins although it is known to have occurred. This table assumes you were born in the year 2000.

An interesting story in the Monday July 3, 2006 Journal Gazette newspaper by Matt Crenson discusses the mathematical probability that all living humans today have a common ancestor if you go back 2,000 to 5,000 years. This is discussed in the 2002 book Mapping Human History by Steve Olson. Olson states that if you go back 5,000 to 7,000 years we would all have the same set of ancestors. An interesting observation made was that "every Palestinian has Jews in his past. Every Sunni Muslim in Iraq is descended from at least one Shiite. And every Klansman has African roots."

Year Generation Total Ancestors   Surnames
2000
1
You
You
1
1975
2
2
2 parents
2
1950
3
6
4 grandparents
4
1925
4
14
8 g grandparents
8
1900
5
30
16 gg grandparents
16
1875
6
62
32 ggg grandparents
32
1850
7
126
64 gggg grandparents
64
1825
8
254
128 ggggg grandparents
128
1800
9
510
256 gggggg grandparents
256
1775
10
1,022
512 ggggggg grandparents
512
1750
11
2,046
1,024 gggggggg grandparents
1,024
1725
12
4,094
2,048 ggggggggg grandparents
2,048
1700
13
8,190
4,096 gggggggggg grandparents
4,096
1675
14
16,382
8,192 ggggggggggg grandparents
8,192
1650
15
32,766
16,384 gggggggggggg grandparents
16,384
1625
16
65,534
32,768 ggggggggggggg grandparents
32,768
1600
17
131,070
65,536 gggggggggggggg grandparents
65,536
1575
18
262,142
131,072 ggggggggggggggg grandparents
131,072
1550
19
524,286
262,144 gggggggggggggggg grandparents
262,144
1525
20
1,048,574
524,288 ggggggggggggggggg grandparents
524,288
1500
21
2,097,150
1,048,576 gggggggggggggggggg grandparents
1,048,576

Continuing with the newspaper story, by the 13th century we would have 1 billion ancestors and 40 generations ago in the 9th century we would have a trillion ancestors. 1,200 years ago there were only 200 million people on Earth. "Simple division - 1 trillion divided by 200 million - shows that each person back then would appear 5,000 times on the family tree of every single person living today ... It is mathematically inevitable that at some point, there will be a person who appears at least once on everybody's tree."

Genealogy research is never complete, important details might be missing, and often contains errors, so let me know if your research contradicts mine. My Indiana and Ohio family research comes from conversations with relatives, scrapbooks, library research, online records, visits to courthouses, final resting places on family farms and cemeteries. Families in other states rely mostly on the research of others. Links to other web sites often change then won't work, so if you find broken links, have additional information on any families, corrections, photos, or anything to add to the history of our families, please leave a Comment in my Guest book, join my Follis Families on Facebook page for updates and new discoveries, or send an Email. The Wayback Machine archives most old web pages so copy and paste the broken URL address to find the missing 404 pages that disappeared. Read Dick Eastman's newsletter on using Unverified Data from the internet. This web site is designed to work with JavaScript and the latest browsers. If you experience display problems you may need to update your browser.

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