I worked out in my head that over the last 200 years roughly one thousand of my ancestors existed.
I was thinking about my ancestors, how many of them there are. We have 2 parents, 4 grand parents, 8 great grandparents. Both our parents have 2 parents each so each level of our ancestry doubles. I was thinking that the average person has a child when they're in their 20s so each generation should represent 20 to 25 years, 4 generations of a family is roughly 100 years. 
Generation 4 is 16 great great grandparents, generation 5 is 32 great great great grandparents, generation 6 is 64 great great great great grandparents, generation 7 is 128 great great great great great grandparents, generation 8 is 256 great great great great great great grandparents, generation 9 is 512 great great great great great great great grandparents, 200 years and about 1000 ancestors. Then generation 10 had 1024 great great great great great great great great grandparents all alive at the same time. One thousand forgotten stories and lost thoughts. I know very little about them.
The same could be true of my descendants, if my descendants have 2 children each at 20 to 25 years of age on average then after 200 to 250 years I would have about one thousand living descendants.
