How Many Direct Ancestors Do You Have?
Oh I hope I’m wrong. Please tell me I’m wrong. It’s quite possible. It’s 1am and I’m still kind of drunk. But as I was trying to get to sleep, this question bugged me:
“How many people lived and died for me to be here?”
In other words, “How many direct ancestors do I have?”
The reason this is an important question is because I know that I am the legacy of those ancestors. In most cases, the ONLY thing they left behind to show they were here, were their children and grandchildren. Their DNA. I am their legacy.
So how many direct ancestors do I have?
I know I had two parents. They had to live for me to be here. They each had two parents. And so forth and so on, back in time. Let’s say that, on average, each set of parents procreated the next generation when they were about 30 years of age. How many ancestors do I have?
This problem bothered me enough that I had to get back up and knock out a simple spreadsheet to work it out.
I got as far as 10,000 years (approximately 8000 B.C.E.) and gave up.
If I go back 60 years, I have 6 ancestors - my parents (2) and my grand-parents (4) = 6.
If I go back 90 years, I have 14 - the above plus my great-grandparents (8).
Now… if I go back 500 years, I have 262,142. Feeling the burden of responsibility yet??
Go back 1000 years - 34,359,738,366 (aka 34 billion).
Go back 2000 years - 295,147,905,179,353,000,000 (295 quintillion).
Go back 10,000 years - 34,996,011,596,528,200,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000 (yeah.. whatever. But it’s 3.4996E+100).
Now… how old is the human race (fundamentalist Christians need not answer)? According to Wikipedia
“The most widely accepted view among current anthropologists is that Homo sapiens originated in the African savanna around 200,000 BP.”
I don’t think Excel could handle those orders of magnitude.
So unless I’m wrong (PLEASE tell me I’m wrong), this many humans lived, scratched out a living in the dirt, fought desperately against the elements, and then died - all so I could be here. So YOU could be here.
WE ARE THEIR LEGACY.
Here’s the question I am asking myself - WHAT AM I DOING TODAY TO LIVE UP TO THAT RESPONSIBILITY?
……..
Please tell me I’m wrong.
I’m going to try to go to sleep.
May 3rd, 2007 at 2:02 am
ask god.
May 3rd, 2007 at 3:58 am
Hi Cam,
The math is a little wonky as you have the population of your ancestory outstripping the total population of the world. Wikipedia lists the estimate of total number of people to have ~ever~ been born as around 125 billion.
It’s probably safe to assume that the branches of the family tree fork back together again and again throughout time. A geneticist would likely be able to better tell you at what population size the numbers even out.
But how’s this for mind numbing facts. 5% of the entire population of the species, throughout all history … are alive here and now.
May 3rd, 2007 at 8:49 am
Basically it comes down to inbreeding. I can’t find a link to the actual explanation, but it is in here somewhere: http://www.talkorigins.org/indexcc/
May 3rd, 2007 at 8:53 am
I’m sure there is a better resource out there, but my google fu is weak on this topic. Try the comments on this page for a better explanation: http://blogs.msdn.com/calvin_hsia/archive/2004/07/11/180353.aspx
May 3rd, 2007 at 9:26 am
So roughly 3.5 google ancestors after 10,00 years… just wanted to use google in it’s original context. It’s such a rare opportunity.
That number sounds rather big though. I heard that the global population doubles every 50 years or so. The maths is really bad, but as an indication, it means that the global population tends to zero at around 300AD. Again the maths is full of holes but the sum of these populations is only 14 trillion. That really rough figure is way off 3.5 google.
So how many people have ever lived??
May 3rd, 2007 at 9:51 am
sorry should have refreshed before i posted the comment =)
May 3rd, 2007 at 10:01 am
Yeah so how do we make this work?
I tell ya, I could NOT sleep last night, this idea was bugging me. Obviously the numbers I’ve got are ridiculously huge. So then, how does it all map out? Every generation had parents. And surely inbreeding couldn’t have been THAT common… was it? A few thousand years ago, was the entire human race just like… Tasmania???
May 3rd, 2007 at 12:23 pm
inbreeding is the key to making it sound less than that number, if you were talking about how many people you needed then yes it is that many but for all those numbers it is not distint people. also we don’t know how many people where alive when sparta was around etc because they say they killed many hundreds of people. with only an army of 100??? don’t know if its true but if they had wars on such a grand scale it would account while the total world population is so small yet our anscestors is so great ;).
btw off topic but how much does it cost to send a single book from from amazon.com to australia?? want to get
http://www.amazon.com/Sun-Suns-Virga-Book-1/dp/0765315432
May 3rd, 2007 at 2:24 pm
Dude, You have way too much time on your hands. What the hell difference does it Make what your doing wih your life now to people who lived 10,000 years ago. I can guarantee they weren’t worried what you be doing now back then.
Counting sheep or warm milk is a better way to get to sleep.
Maybe I am selfish but I don’t really care what my ancestors 3-4 generations did to ensure that I am here now or whether I should be living up to a legacy. I am here now and do what I do, People in 100 years won’t be worried about the legacy I left so why I should be worried about people 10,000 years ago.
I think I sometimes overthink things too much but you take things to an extreme.
May 3rd, 2007 at 8:19 pm
Will - it costs too much. Even with the strong dollar. Do what I do - walk down to your local indy bookstore and ask them for a quote to get it in for you. They will usually cover the cost of the S&H.
May 3rd, 2007 at 8:22 pm
Tony - I really am feeling the weight of the sense of responsibility I have to my ancestors as well as my descendants. I want to be a good ancestor.
So can’t anybody explain to me why these numbers don’t work? Why are my numbers WAYYY too big? Just saying “inbreeding” doesn’t explain it.
May 3rd, 2007 at 11:15 pm
Hey Cameron,
I’ve read a great book that explains it, called “Mapping Human History” by Steve Olsen. You should be able to read the relevant pages on Amazon:
http://www.amazon.com/gp/reader/0618091572/ref=sib_dp_pt/103-7819944-7687015#reader-link
Search the book for “this is getting ridiculous”. Read from that page on (you might need to be logged in to Amazon for it to work). Should be pages 44-46 I think. If you’re interested, I could even lend you the book (If I’m correct, I don’t live that far away from you, I’m in Maribyrnong). You’d enjoy too I’m sure - it seems our interests cross at more than a few eclectic points!
Cheers
May 4th, 2007 at 12:32 am
I’ve got no answer for that question, but your estimate of average age of your ancestors would be way off I think, as in past generations people tended to breed at a much younger age than today. In most primitive civilizations, as I understand, people aged 30 to 35 would be considered the “old” ones. Most would have died much younger than that.
May 4th, 2007 at 1:22 am
By inbreeding, we’re not talking the ‘nuthin says lovin like marrying your cousin sort. But more likely that a husband/wife pair from one generation had a relative in common back ten, twenty steps previous.
But all life on earth is related - one way or another - in that at some point we’ve all descended from the same common ancestor. I recall hearing from one podcast or another (perhaps biotech nation?) that the same bits of DNA that are responsible for the segmentation of an insect’s thorax are part and parcel of what becomes our spinal column.
So even putting aside the numbers of humans… how many species had to rise and fall and be struggled against to get you to the point where you can sit out on the porch and enjoy a cool beer on a warm autumn’s day?
May 4th, 2007 at 8:23 am
Like Rob Clark says, think of it as common ancestory rather than inbreeding. In some ways its like the six degrees of separation thing that says everyone’s connected.
It really it true to say that we’re all related. I’d love to know how many “degrees of relatedness” you have to go back in order to have a good chance of being related to everyone who’s alive today.
May 4th, 2007 at 8:41 am
Dean - you’re my freakin hero. That book is perfect. I read a few pages on Amazon and I’m going to order it today.
So the ‘inbreeding’ thing is right but it actually IS about “marrying your cousin” Rob. You got back 40 or so generations and pretty much everyone is marrying their cousin. And cousins have at least of one set of shared grandparents. Which compresses the math.
But still - while that may stop my quintillion numbers from arising, we are still left with the fact that 1000 years ago, your ancestors, my ancestors, were pretty much the entire population of a country. Go back much further and our ancestors were the entire extant human race.
Mind boggling.
May 7th, 2007 at 7:45 pm
Cam, it is not so much inbreeding, but siblings. Your numbers sort of assume no inbreeding, but also only a *single child* per “breeding pair”. My two children share the same two immediate ancentors - as far as I know ;), the same 6 ancestors back another generation, and so on.
May 7th, 2007 at 8:54 pm
Hey Bernard! I’m not sure why the number of children matter. The total number of MY ancestors is the same whether or not I have siblings. The fact that I have two sisters doesn’t alter the number of ancestors I personally have. And even that number grows to ridiculous sizes if I keep adding two parents for everyone on the list. So I guess it means that some of them had to be related and have the same parents or grandparents. Quite honestly I still can’t really see in my minds eye how even that concession gets the numbers down small enough though.