Humans are more closely related than we commonly think
scientificamerican.com
Humans are more closely related than we commonly think
1–10 of 142 posts
Re: Humans are more closely related than we commonly think
#2Relevant xkcd: https://xkcd.com/1545/ (sorry) ;)
Re: Humans are more closely related than we commonly think
#3While this article's content isn't exactly wrong, the Wikipedia on "Identical ancestors point" gives some important context for what's actually being asserted:
All living people share exactly the same set of ancestors from this point back, all the way to the very first single-celled organism. However, people will vary widely in how much ancestry and genes they inherit from each ancestor, which will cause them to have very different genotypes and phenotypes.
This is illustrated in the 2003 simulation as follows: Considering the ancestral populations alive at 5000 BC, close to the ACA point, a modern day Japanese person will get 88.4% of his ancestry from Japan, and most of the remainder from China or Korea, with only 0.00049% traced to Norway; conversely, a modern-day Norwegian will get over 92% of his ancestry from Norway (or over 96% from Scandinavia) and only 0.00044% from Japan. Thus, even though the Norwegian and Japanese person share the same set of ancestors, these ancestors appear in their family tree in dramatically different proportions.
A Japanese person in 5000 BC with present-day descendants will likely appear trillions of times in a modern day Japanese person's family tree, but might appear only one time in a Norwegian person's family tree. A 5000 BC Norwegian person will similarly appear far more times in a typical Norwegian person's family tree than he will appear in a Japanese person's family tree.
Re: Humans are more closely related than we commonly think
#4While this article's content isn't exactly wrong, the Wikipedia on "Identical ancestors point" gives some important context for what's actually being asserted: All living people share exactly the same set of ancestors from this point back, all the way to the very first single-celled organism. However, people will vary widely in how much ancestry and genes they inherit from each ancestor, which will cause them to have…
An intuition about the "appearing trillions of times in a family tree" is to realize that family trees are actually a binary tree extending backwards in time--i.e. each person has exactly two parents, who have exactly two parents, and so on. So N generations back, there are 2^N individuals. Obviously, there weren't 2^100 people on Earth at any point in time, so this backwards tree starts folding back on itself, containing duplications. Go back far enough and there is a set of individuals who were alive at a particular point in time that completely cover that forward tree.
It helps to visualize this more as a mesh than a tree, or as a flowing river. The river divides around rocks and obstructions (those are points of temporary divergent evolution) but ultimately all flows together (convergent ancestry). We are truly one body of genetic material, and yet each is a unique combination of backwards traces.
It's really very cool IMHO.
Re: Humans are more closely related than we commonly think
#5While this article's content isn't exactly wrong, the Wikipedia on "Identical ancestors point" gives some important context for what's actually being asserted: All living people share exactly the same set of ancestors from this point back, all the way to the very first single-celled organism. However, people will vary widely in how much ancestry and genes they inherit from each ancestor, which will cause them to have…
The point in the article is that at many generations ago, we are heavily inbred, it is not that we are all related.
If you look at one generation ago one have 2 * 2 ^ 0 ancestors, at two generations, one have 2 * 2 ^ 1 ancestors, etc. At 27 generations one apparently has more ancestors than people in the world at that time. This apparent paradox stems from the fact that we are heavily inbred.
Thus the article is correct.
Re: Humans are more closely related than we commonly think
#6So I was wondering if this article was just being incredibly misleading or straightforwardly lying, and I hit this:
> “If you were alive at the genetic isopoint, then you are the ancestor of either everyone alive today or no one alive today,”
Yeah. That's a lie. There's no way around it, this is a dishonest statement.
I'm in no kind of mood to explain why that is, for pretty predictable reasons this conversation goes to places I'm not fond of.
But it ain't true, and I'm willing to explain why people might wish it was: 12 generations back, you have absolutely no DNA from some of your ancestors. That's how recombination works, the deck is shuffled in a "chunky" way and some of your ancestors get shuffled out.
So all those Europeans have no (dig this: zero) genes in common with Sub-Saharan Africans that weren't conserved 90,000 years ago either because: they don't have an African ancestor (the answer) or because they are descended from all Africans alive in 5000BCE and the genes all got shuffled out because reasons, which is, not the answer.
It's a nice story and I'd love to believe it, if it was true, which it isn't.
Re: Humans are more closely related than we commonly think
#7So I was wondering if this article was just being incredibly misleading or straightforwardly lying, and I hit this: > “If you were alive at the genetic isopoint, then you are the ancestor of either everyone alive today or no one alive today,” Yeah. That's a lie. There's no way around it, this is a dishonest statement. I'm in no kind of mood to explain why that is, for pretty predictable reasons this conversation goes…
Do you have a citation? Because that’s not what Wikipedia says https://en.m.wikipedia.org/wiki/Identical_ancestors_point
Re: Humans are more closely related than we commonly think
#8My relatives would sometimes talk about how we were related to some deposed king or some princess who ran away to avoid being married. I thought it's likely there's enough princesses and undocumented deposed kings out there that everyone should have a great-great-grandaunt who was a legitimate princess in their lineage. This article supports that theory.
Re: Humans are more closely related than we commonly think
#9Weren't Australian Aboriginals isolated for tens of thousands of years and some full blooded individuals still exist today? How could they have an ancestor outside Australia in only 1400 BC?
Re: Humans are more closely related than we commonly think
#10This was also a conclusion in a thoughty2 youtube video I watched:
This Is Why Inbreeding Is So Dangerous https://www.youtube.com/watch?v=hmv-z851BOE
I'm pretty this is why people all over the world like to keep track of their ancestry. People who don't will be more closely inbred.