Grandparents ~ Somebody check my math - something doesn't add up!

[Gleb Gamow]

Facts:

- A generation = 25 years (using the highest number in lieu of 20, the number of years for earlier generations)
- 2⁴⁰ = 1,099,511,627,776
- 40 X 25 = 1,000

Given the above, a thousand years ago I had over a trillion grandparents. Correct?

Question: What was the population of the Earth a thousand years ago? Was it over a trillion?

[1715257434]

1715257434

[1715257434]

1715257434

[1715257434]

1715257434

[PoorLad]

Reality check: People die. Every single second almost 2 people die

[Gleb Gamow]

Reality check: People die. Every single second almost 2 people die

People dying regardless the rate has nothing to do with what was presented. For you or I to be here today, we each would had to have a trillion grandparents 40 generations ago. That fact is undisputed [unless my math and assessment is in error, hence seeking input from those learned].

[PoorLad]

It was on the population thing Wiki say we was between 255 and 400mill people 1000 years ago.

[Hannu]

Reality check: People die. Every single second almost 2 people die

Have you ever listen earth voice on space?

[R.R. Toulkens]

Obviously we share common ancestors, not to mention one male can get any number of females pregnant. You don't need 20 people to generate 10 people, actually just a couple suffices.

[Gleb Gamow]

Obviously we share common ancestors, not to mention one male can get any number of females pregnant. You don't need 20 people to generate 10 people, actually just a couple suffices.

Okay, let's do the reverse.

Pretend that a thousand years ago there were only two people on the planet. They had two children, a boy and girl. Forty generations later, that equates to a trillion offsprings, of which there has never been a trillion people total on this planet.

[PatioCrasher]

Facts:

- A generation = 25 years (using the highest number in lieu of 20, the number of years for earlier generations)
- 2⁴⁰ = 1,099,511,627,776
- 40 X 25 = 1,000

Given the above, a thousand years ago I had over a trillion grandparents. Correct?

Question: What was the population of the Earth a thousand years ago? Was it over a trillion?

This is an interesting dilema and thought process.  But I doubt the populations ever grew at that rate.

Think about tribes. They would probably roughly grow to about double or triple in size before probably being annialated by another tribe (At least thats what I beleive happened here in Africa.. )

[Gleb Gamow]

Facts:

- A generation = 25 years (using the highest number in lieu of 20, the number of years for earlier generations)
- 2⁴⁰ = 1,099,511,627,776
- 40 X 25 = 1,000

Given the above, a thousand years ago I had over a trillion grandparents. Correct?

Question: What was the population of the Earth a thousand years ago? Was it over a trillion?

This is an interesting dilema and thought process.  But I doubt the populations ever grew at that rate.

Think about tribes. They would probably roughly grow to about double or triple in size before probably being annialated by another tribe (At least thats what I beleive happened here in Africa.. )

https://answers.yahoo.com/question/index?qid=20061106182557AAmbeKh

Scientifically it is considered between 22 and 25 years.

I chose 25 years as a working figure to illustrate my stance, but will gladly recalculate using any number of years between generation up to 50 years on average, albeit hell, even 70 years between gens gleaned from the KJV would suffice.

[Foxpup]

You're talking about pedigree collapse, and what doesn't add up is that many of your trillions of great⁴⁰ grandparents are in fact the same person due to inbreeding, which is unavoidable since everyone is related to everyone else in the world.

[Gleb Gamow]

<Addressing the last post in a sec. Guys, I'm not tryin' to troll here, albeit it kinda reads like a Flat-earther defending his position.  I'm fully capable of conceding my stance once shown where I'm in error. Look forward to reading your arguments. Thanks, guys.>

Here's a table depicting a child born in the year 2000 having parents both 25 years of age (born 1975; first row), with all grandparents also 25 years old [for sake of illustration].

[As with subsequent rows] we can all relate to the second row, all of us having 2 parents and 4 grandparents for a running total of 6 distinct people (excluding ourselves/exampled millennium child), ancestors born in the years depicted in the last column.

I duly hope that the table is self-explanatory from there on out. If not, please inquiry. First, a pic to help illustrate the table:

After 8 generations, all 128 great-grandparents are distinct.
254 distinct people are depicted.

Generations	Dad's Parents	Mom's Parents	Running Total	Years (Date)
1	1	1	2	25 (1975)
2	2	2	6	50 (1950)
3	4	4	14	75 (1925)
4	8	8	30	100 (1900)
5	16	16	62	125 (1875)
6	32	32	126	150 (1850)
7	64	64	254	175 (1825)
8	128	128	510	200 (1800)
9	256	256	1,022	225 (1775)
10	512	512	2,046	250 (1750)
11	1,024	1,024	4,094	275 (1725)
12	2,048	2,048	8,190	300 (1700)
13	4,096	4,096	16,382	325 (1675)
14	8,192	8,192	32,766	350 (1650)
15	16,384	16,384	65,534	375 (1625)
16	32,768	32,768	131,070	400 (1600)
17	65,536	65,536	262,142	425 (1575)
18	131,072	131,072	524,286	450 (1550)
19	262,144	262,144	1,048,574	475 (1525)
20	524,288	524,288	2,097,150	500 (1500)
21	1,048,576	1,048,576	4,194,302	525 (1475)
22	2,097,152	2,097,152	8,388,606	550 (1450)
23	4,194,304	4,194,304	16,777,214	575 (1425)
24	8,388,608	8,388,608	33,554,430	600 (1400)
25	16,777,216	16,777,216	67,108,862	625 (1375)
26	33,554,432	33,554,432	134,217,726	650 (1350)
27	67,108,864	67,108,864	268,435,454	675 (1325)
28	134,217,728	134,217,728	536,870,910	700 (1300)
29	268,435,456	268,435,456	1,073,741,822	725 (1275)
30	536,870,912	536,870,912	2,147,483,646	750 (1250)
31	1,073,741,824	1,073,741,824	4,294,967,294	775 (1225)
32	2,147,483,648	2,147,483,648	8,589,934,590	800 (1200)
33	4,294,967,296	4,294,967,296	17,179,869,182	825 (1175)
34	8,589,934,592	8,589,934,592	34,359,738,366	850 (1150)
35	17,179,869,184	17,179,869,184	68,719,476,734	875 (1125)
36	34,359,738,368	34,359,738,368	137,438,953,470	900 (1100)
37	68,719,476,736	68,719,476,736	274,877,906,942	925 (1075)
38	137,438,953,472	137,438,953,472	549,755,813,886	950 (1050)
39	274,877,906,944	274,877,906,944	1,099,511,627,774	975(1025)
40	549,755,813,888	549,755,813,888	2,199,023,255,550	1,000 (1000)

The ONLY way any of us could've had less than 1,099,511,627,776 grandparents during the course of the last 1,000 years as depicted above, is if a few of the generation spans were longer than 25 years, thus to compensation, simply add another 25 years to the mix, resulting in 2,199,023,255,552 (2.199+ trillion) grandparents to assure at least one trillion grandparents. <I guess there's other ways, but will let this graph stand unedited (this note included prior to publishing)>

Historically, parents, especially women, were much younger than 25 years old hundreds of years ago.

[Gleb Gamow]

You're talking about pedigree collapse, and what doesn't add up is that many of your trillions of great⁴⁰ grandparents are in fact the same person due to inbreeding, which is unavoidable since everyone is related to everyone else in the world.

https://en.wikipedia.org/wiki/Pedigree_collapse

Without pedigree collapse, a person's ancestor tree is a binary tree, formed by the person, the parents (2), the grandparents (4), great-grandparents (8.), and so on. However, the number of individuals in such a tree grows exponentially and will eventually become impossibly high. For example, a single individual alive today would, over 30 generations going back to the High Middle Ages, have 2³⁰ or roughly a billion ancestors, more than the total world population at the time.

This apparent paradox is explained by shared ancestors, referred to as pedigree collapse. Instead of consisting of all different individuals, a tree may have multiple places occupied by a single individual. This typically happens when the parents of an ancestor are related to each other (sometimes unbeknownst to themselves). For example, the offspring of two first cousins has at most only six great-grandparents instead of the normal eight. This reduction in the number of ancestors is pedigree collapse. It collapses the ancestor tree into a directed acyclic graph.

Are we saying that of the 7.442+ billion people living today along with those who've died during the past 100 years, not a one of them had a quasi-pure ancestor lineage for 30 generations?