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Humans are more closely related than we commonly think

scientificamerican.com

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Re: Humans are more closely related than we commonly think

#111

Post by [deleted] »

coldtea wrote: post #55
titzer wrote: post #4

Earlier quoted context omitted.

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, cont…

> 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. So like Adam and Eve? :-)

[deleted]

Re: Humans are more closely related than we commonly think

#112

Post by rendall »

throwanem wrote: post #75
rendall wrote: post #71

Earlier quoted context omitted.

It is true. It has run away with us all

What are you actually talking about, though? Veiled and gnomic proclamations can be fun, but sooner or later you have to show your hand.

The fish represents the lost dreams of our ancestry, if not the fishy ancestors themselves. The man is us, all of us. The hungry family is our hungry family. Or perhaps our hunger for connection to our past. The story as a whole is meaningless, and in being so, represents the randomness and chaos in which we find ourselves. Is the universe beneficent, malevolent, indifferent? We cannot know for sure. We can only stare into the dying eyes that stare at us in turn, from the mirror, and guess.

Re: Humans are more closely related than we commonly think

#113

Post by delecti »

shuringai wrote: post #23

Problem is, The article assume humans mate with uniform distribution, and that they did so generations ago. The 2^n argument is way naive and this level of uniformity assumes every people on earth has the chance to end up with a uniform random other person as their partner, regardless of geographic, cultural etc differences.

Doesn't that only support their point? A naively optimistic estimate that ancestors are uniformly distributed will take more generations to hit the limit of 2^n vs the historic population. In reality ancestors are "reused" even faster than that, particularly with examples like geographically isolated villages, etc.

Re: Humans are more closely related than we commonly think

#114

Post by tsimionescu »

goto11 wrote: post #46
piokoch wrote: post #40

Earlier quoted context omitted.

Hmm, I was really surprised about the part on woman creation, as I've never read such version (in Polish), but, indeed this https://www.biblegateway.com/passage/?search=Genesis+2&versi... (very) strange translation mentions woman to be taken from man's rib. This translation https://www.biblegateway.com/passage/?search=Genesis%201&ver... looks much better "So God created mankind in his own image, in the image of God h…

You are looking at two different verses. NIV have basically the same text for Genesis 2:21: https://www.biblegateway.com/passage/?search=Genesis+2%3A21&... > So the Lord God caused the man to fall into a deep sleep; and while he was sleeping, he took one of the man’s ribs and then closed up the place with flesh.

I had heard a different theory, that this may be a mythological explanation on why humans don't have a penile bone like many common farm animals at that time (with 'rib' being a mistranslation of a more vague 'bone'). This would also make more symbolic sense, as a penile bone would be more obviously related to creation than a rib.

Re: Humans are more closely related than we commonly think

#115

Post by simonh »

etabetapi wrote: post #102
simonh wrote: post #38

Earlier quoted context omitted.

The 'recent dispersal' started some 70-50,00 years ago, reaching Europe about 40,000 years ago. https://en.wikipedia.org/wiki/Early_human_migrations#Homo_sa... Europeans have pretty low levels of sub-saharan genetic markers, with some remnant markets in southern Europe dating to the late Roman era, diminishing substantially as you move north. https://en.wikipedia.org/wiki/African_admixture_in_Europe

This is tautological, sub-saharan genetic markers are found predominantly in sub-saharan populations by definition. Given how humanity has evolved, "european" markers are a subset of the diversity found in subsaharan populations that are overrepresented from founder effects, with very few exceptions. 40,000 years ago sounds like a long time, but it really isn't. You need an amazingly small amount of migration (about…

I get your point. I'm somewhat surprised that the person I was responding to seemed to think it would even need a citation, but there you are.

>You need an amazingly small amount of migration (about one person per generation) to keep a population in sync with each other genetically.

Well it depends on the size of the population, but even then I don't see how this can be the case. One individual only contributes half their genes to each child, so assuming 2 surviving children that's a 25% lost immediately in the next generation. In just a few generations about half the incomer's genes will be lost in this way. The remainder will likely persist, but equally the number of their descendants that have none or very few of their genes will rise to predominate. In a stable population of 1,000 people, one single individual is unlikely to contribute much more than 1/2,000th of the genes in circulation.

Re: Humans are more closely related than we commonly think

#117

Post by acephal »

sfblah wrote: post #116

The article asserts that all people have some European ancestry. I strongly doubt that. Consider uncontacted tribes in Papua New Guinea, the Amazon rainforests or Sentinel Island.

>At first glance, these dates may seem much too recent to account for long-isolated Indigenous communities in South America and elsewhere. But “genetic information spreads rapidly through generational time,” Rutherford explains. Beginning in 1492, “you begin to see the European genes flowing in every direction until our estimates are that there are no people in South America today who don’t have European ancestry.”

Re: Humans are more closely related than we commonly think

#118

Post by throwanem »

rendall wrote: post #112
throwanem wrote: post #75

Earlier quoted context omitted.

What are you actually talking about, though? Veiled and gnomic proclamations can be fun, but sooner or later you have to show your hand.

The fish represents the lost dreams of our ancestry, if not the fishy ancestors themselves. The man is us, all of us. The hungry family is our hungry family. Or perhaps our hunger for connection to our past. The story as a whole is meaningless, and in being so, represents the randomness and chaos in which we find ourselves. Is the universe beneficent, malevolent, indifferent? We cannot know for sure. We can only star…

Nobody likes a smartass.

Re: Humans are more closely related than we commonly think

#119

Post by [deleted] »

rsynnott wrote: post #82
alea_iacta_est wrote: post #81

> Humans left Africa and began dispersing throughout the world at least 120,000 years ago, but the genetic isopoint occurred much more recently—somewhere between 5300 and 2200 B.C., according to Rohde’s calculations. All the article seems to be based on the Out of Africa hypotesis, but what about the multiregional hypotesis?

> but what about the multiregional hypotesis? The strong multi-regional hypothesis is essentially a dead issue; didn't survive contact with modern genetics. There's now some evidence for regional admixture for genetics from archaic humans with Homo sapiens, and this is sometimes called (kind of misleadingly, IMO), the weak multi-regional hypothesis.

[deleted]

Re: Humans are more closely related than we commonly think

#120

Post by btilly »

acjohnson55 wrote: post #91
genghizkhan wrote: post #56

Earlier quoted context omitted.

Adam: https://en.wikipedia.org/wiki/Y-chromosomal_Adam Eve: https://en.wikipedia.org/wiki/Mitochondrial_Eve

I'm trying to square those articles, which put Y-chromasomal Adam and Mitochondrial Eve >100kya with the Identical Ancestor Point, which is only 5000-15000ya. I guess it's kind of like the difference between a permutation and a combination.

Simple explanation. It is the difference between "things have mixed so much that everyone is your ancestor somehow" and "on a strict matrilineal or patrilineal descent, everyone winds up at the same thing".

In the first the path goes through both fathers and mothers. This is easier to achieve, and so you get to it more recently. The second is harder and so happened longer ago.

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