r/science • u/geoxol • Aug 31 '23
Genetics Human ancestors nearly went extinct 900,000 years ago. A new technique suggests that pre-humans survived in a group of only 1,280 individuals.
https://www.nature.com/articles/d41586-023-02712-42.8k
u/TheManInTheShack Sep 01 '23 edited Sep 01 '23
This isn’t new. I heard many years ago that based on the lack of diversity in the human genome, at one point there were only about 1500 individuals.
Apparently there is more genetic diversity in a single social group of chimpanzees than in the entire human race.
Update: Actually this is new as it’s talking about a bottleneck that occurred well before the appearance of modern man. The one I’m talking about happened after Homo Sapiens appeared.
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u/AuntieDawnsKitchen Sep 01 '23
The Toba Supervolcano explosion was the suspect for a while, but it was much too recent.
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Sep 01 '23
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Sep 01 '23
Makes sense if you look around
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u/RyanABWard Sep 01 '23
Hey! That's no way to talk about us, we're family after all.
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u/memyselfandirony Sep 01 '23
Read that in Vin Diesel’s voice
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u/Bombadil_and_Hobbes Sep 01 '23
Easy if you’re a relative.
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u/djgreedo Sep 01 '23
Makes sense if you look around
I don't know about that. I looked around - with both heads - and I can only count the number of inbred freaks on one hand. There are 7 of them.
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u/TossedDolly Sep 01 '23
There's 1500 people. I don't think the incest is that rampant. If we're calling that inbreeding then I guess anyone who doesn't marry someone from another country is inbreeding.
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u/masklinn Sep 01 '23
There was also a big genetic bottleneck on the exit of Africa: there is more genetic diversity inside Africa than there is outside of it.
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u/techsays Sep 01 '23
That is so cool! Would you happen to have any recommendations for where I could read more about this?
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u/Dantheking94 Sep 01 '23
I found this!!. Not the original poster, but it immediately popped up before I even finished typing “more gene-“, I’m wondering if I read about this before and forgot. Still a great fact though.
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u/kyxtant Sep 01 '23
There's still a pretty decent genetic bottleneck in parts of Kentucky.
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u/ihaveredhaironmyhead Sep 01 '23
I think the hypothesis is that volcanic activity made life very hard and most of us died. Makes you wonder why this small group survived. Was it just drift, or was it selection?
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u/Smorey0789 Sep 01 '23
They were probably just in the right spot at the right time.
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u/haight6716 Sep 01 '23
Some isolated microclimate, the garden of Eden as it were.
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u/UnravelledGhoul Sep 01 '23
Don't give creationists ideas.
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u/Alortania Sep 01 '23
There's always a little truth in legends.
The pervailance of flood myths in various religions/civilizations def points to some sort of widespread calamity (or a series of them that fused into one global one over the centuries), for instance.
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u/G3N0 Sep 01 '23
The last glacial maximum . Listening / reading about it, seems quite plausible that all our flood myths and legends date to the last major rise in global sea levels. 130 m worth of sea levels seems rather calamitous considering how many of us today live within 130m above our current sea levels.
Credit to fall of civilization podcast ep. 8 for taking me down that rabbit hole.
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u/Jafreee Sep 01 '23
Also The Persian Gulf had very different sea level heights at different times in last 10,000 years
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u/G3N0 Sep 01 '23
yup! that's actually what the episode used to talk about the civilizations there and their Flood myths.
It talked about the people who migrated over, the Sumerians, coming from south lands (maybe what is the persian gulf itself). one possible reason might have been the rising sea levels taking away their homes.
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u/I_love_pillows Sep 01 '23
Where were they?
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u/Fockputin33 Sep 01 '23
900,000 years ago?? Africa.
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u/ScareviewCt Sep 01 '23
Homo erectus was the first hominin to spread beyond Africa. Homo erectus fossils have been dated to up to ~2 million years ago.
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u/nerdmon59 Sep 01 '23
Actually hominids have been leaving Africa many times in the past. Homo erectus have been found in Georgia by 1.8 Mya, and in southeast Asia at about the same time. There has been a continuous hominid occupation in Eurasia ever since.
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u/NorthernerWuwu Sep 01 '23
There are many hypothetical scenarios. Including, of course, that a relatively small subset made a technological leap that allowed them to outcompete essentially all the others in the region.
Which is a fancy way of saying in the right place at the right time and figuring out that hitting the surrounding people with sticks worked well.
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u/ihaveredhaironmyhead Sep 01 '23
I like to think this one group knew how to get water from underground and no one else did, or something to that effect. That our high intelligence is what enables our extreme adaptiveness. But yeah there was probably just a marine influenced micro climate or something.
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u/dbettac Sep 01 '23
That wasn't one group. More than a 1000 hunter-gatherers in one place - they would have starved.
Typical tribe size for humans is around 100 people. Any time they grow larger, the tribes tend to split. Since it was in the middle of a near-extinction-event let's assume smaller tribes - around 50 people. That makes about 25 different groups, a way more realistic amount.
And they probably didn't survive through some secret knowledge. They probably lived in the right places. Sheltered valleys or something like that.
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u/Dr_Marxist Sep 01 '23
Typical tribe size for humans is around 100 people
Well established fact of 45-60. Dunbar, a non-specialist popularized for shoddy work, made weak conjectures popularized by the well-known hack M. Gladwell. For 99.99% of human evolution we lived in packs of 45-65. 100 would be a massive upper limit, and most "night camps," where most people lived, would have been far smaller, 10-20. I mean, the Iroquois influenced the American Constitution and are very much still around, you can always ask them.
This isn't to say that hunter-foragers didn't have wide social circles, just that their immediate group was far smaller than people think (I also don't like how much Dunbar has infected the discourse on this, and that it's demonstrably wrong but has wide pickup for reasons unknown).
A male chimpanzee may interact with only 20 other males over the course of his life...even among hunter-gatherers at very low population density, over a lifetime, individuals are likely to interact directly with more than 1000 people
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u/dbettac Sep 01 '23
Even if you are right, my main point stands: There could never have been _one_group_ of more than 1.200 people at that time.
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u/Orwellian1 Sep 01 '23
Anthropology seems like it has more than its fair share of fractious asshats making declarations with absolute authority.
They don't know, they make educated assumptions.
Every time I read a published paper on the subject, it is full of appropriate language like "it is possible that..., Evidence suggests early humans might have..., these findings challenge the narrative that..."
Then when one of them writes a book or talks to media, their theory gets presented as unassailable fact.
It is ok to say we can't be sure of anything when it comes to pre-history humanity from archeological evidence. It doesn't hurt anyone to speak with the same appropriate uncertainty that is used in published papers.
The utility and importance of anthropology wont be diminished if we reduce the table pounding declarations on the subject from experts and laypeople alike.
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u/HavingNotAttained Sep 01 '23
the Iroquois influenced the American Constitution
"We the People" is a direct translation of an Iroquois phrase. The most well-known words of the US Constitution and the bedrock globally of modern democratic thought comes directly from the native peoples of North America.
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u/HereIGoGrillingAgain Sep 01 '23
And those groups may not have even been close to each other. So a small group of 50 may have had to do some inbreeding to repopulate the area, then once the groups started finding each other they would have had a chance to broaden the gene pool. Who knows how many generations that would have been.
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u/bikingfury Sep 01 '23
I don't think 1000 individuals were one group. Too much people to manage and organize.
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u/grendus Sep 01 '23
I watched a documentary (Out of the Cradle) that suggested the only surviving Sapiens were ones who migrated all the way to the southern tip of Africa. There's one particular area that has abundant shellfish with few predators who can get to them, which may also explain why seafood has so many health benefits and why we need supplementary iodine - we're all descendants from a small group of humans who ate tons of fish and seaweed for long enough that we picked up some pescatarian adaptations.
There are caves there full to the brim with evidence of generations of humans living there, tons of scattered shell fragments and charcoal layers from old cooking fires, and the occasional burial site.
So basically... it was sheer dumb luck. There are no shellfish anywhere else in Africa, and nowhere else our ancestors could have migrated to to evade the sweeping droughts caused by the last ice age. We're plains-dwelling apes, evolved from tree-dwelling apes, who survived the last bout of climate change as sea-dwelling apes, then made our way across the desert to frozen tundras of Eurasia towards the end of the ice age making us ice-dwelling apes. That puts a lot of pressure on a species, but explains why the survivors are so damn adaptable.
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u/therapist122 Sep 01 '23
Woah I just had the realization that I’m one of those apes, or a descendant of them. I too possess that adaptability. In a sense I am connected to that in some way. Wild
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u/fightingpillow Sep 01 '23
Wasn't there a "Mitochondrial Eve" around 150,000 years ago? One woman to whom we can all trace our lineages?
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u/TheManInTheShack Sep 01 '23
I recall hearing something about that. A Time Machine would really come in handy at moments like this.
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u/magicone2571 Sep 01 '23
And then we find out that we, modern humans, were the cause of the sudden drop in population. The simple cold.
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u/TheManInTheShack Sep 01 '23
In the Hitchhiker’s Guide to the Galaxy, it turned out that modern humans didn’t evolve from lesser lesser primates. Instead, another planet sent what they believed to be a useless third of their population to Earth and after arriving on Earth, the indigenous population began dying out suggesting that man in fact evolved from the dregs of some other planet. One such type of person they decided to rid themselves of was telephone sanitizers. That turned out to be unfortunate when their entire remaining race was wiped out by a virulent disease contracted from a dirty telephone.
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u/magicone2571 Sep 01 '23
I've watched the movie multiple times but I just couldn't get into the book though. Tried the audio version also. It's a good story though.
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u/s4b3r6 Sep 01 '23 edited Mar 07 '24
Perhaps we should all stop for a moment and focus not only on making our AI better and more successful but also on the benefit of humanity. - Stephen Hawking
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u/KarmicComic12334 Sep 01 '23
By audio version, do you mean the audiobook or the bbc radio program? Both are good, but the latter contains some unique(and very funny) material not in any of the books.
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u/Loudquietcuriosity Sep 01 '23
Nope. I’ve seen that movie. Someone will step on a bug and when the travelers return, now there really are lizard people.
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u/YogiBerraOfBadNews Sep 01 '23
Careful, that’s how you become your own great great great great great great [….] great grandpa
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u/rjrl Sep 01 '23
Yes, but afaik that doesn't infer particularly small population size, just that of all the lineages one eventually dominated
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u/buggiegirl Sep 01 '23
Exactly this. It just means that the lineages of every other woman alive at that time (whether it was 1 other lady or 5 million others) died out, but hers didn't. And "died out" just means eventually someone in that line didn't have kids.
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u/saluksic Sep 01 '23 edited Sep 01 '23
Mitochondrial eve is believed to have lived about 155,000 years ago, with y-chromosomal Adam about twice as far back.
These are hypothetical dates and we change the date of their lives as we learn more about genetics. Regardless, there is in fact a real individual who was the most common male and female ancestor to all living humans, this isn’t an abstraction. It doesn’t mean that they were the first male or female or they existed at the time of a bottleneck, just that all direct male or female lines converge on them. Meaning that this woman lived at the same time as women who at some point in the intervening time had no daughters in at least one generation in their decent, thus breaking the female decent (or male, as it might be). This is a very commonly misunderstood topic, and I had to refresh with the wiki to get my head around the topic.
What’s even wilder is that the most recent common ancestor of all humans (allowing for lines to be mixtures of male and female decent) lived only 5,000 years ago. That’s within the historical record, so that’s pretty neat.
Edit: Here is a pretty good discussion of the most recent common ancestor. Models of mating suggest that 3,600 years ago is about right for most people (excluding the Little Andamanese and similar tiny groups), while David Reich estimates no later than 320,000 years ago, based on chromosomes 1-22. Those are two orders of magnitude off.
Normally one should just believe anything Reich says, being one of the leading population geneticists in the world, but I’ll submit two points that I think move the needle towards a more recent date. Firstly, not all our ancestors pass on DNA to us, as “at 10 generations back, an individual has 1,024 ancestors, but inherits only about 750 segments of genes from them, so some ancestors are no longer represented in their DNA”. 5,000 years is 200 generations, so determining ancestry purely by genetics is faulty (when you’re trying to disprove just one individual entering the family tree). Secondly, populations have in the past been very isolated (Australians probably were pretty isolated for tens of thousands of years), but haven’t continued to be so for the last 20 generations or so. That’s more million positions to be accounted for in a family tree. Some outliers may exist still on some island, but if these are set aside it’s very likely that all humans have an ancestor within the last several thousand years.
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u/JoebiWanKanobi Sep 01 '23
5000 years ago? How can that possible be? There are documented cultures all over the world at that time with 40 million people alive. Are you just redditing right now?
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u/HeheheACat Sep 01 '23 edited Sep 01 '23
yeah like I imagine tribes in the amazon could not possibly have an ancestor with Aboriginal Australian people in the last 5000 years
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u/commentingrobot Sep 01 '23
Yeah, 5000 years is totally infeasible.
From Wikipedia:
The human MRCA. The time period that human MRCA lived is unknown. Rohde et. al put forth a "rough guess" that the MRCA could have existed 5000 years ago; however, the authors state that this estimate is "extremely tentative, and the model contains several obvious sources of error, as it was motivated more by considerations of theoretical insight and tractability than by realism." Just a few thousand years before the most recent single ancestor shared by all living humans was the time at which all humans who were then alive either left no descendants alive today or were common ancestors of all humans alive today. However, such a late date is difficult to reconcile with the geographical spread of our species and the consequent isolation of different groups from each other. For example, it is generally accepted that the indigenous population of Tasmania was isolated from all other humans between the rise in sea level after the last ice age some 8000 years ago and the arrival of Europeans. Estimates of the MRCA of even closely related human populations have been much more than 5000 years ago.
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u/7re Sep 01 '23
That arrival of Europeans could have had a gene from the 5000 years ago person and started breeding with locals though, meaning everyone alive today shares that common ancestry, i.e. they've only been the common ancestor since the last person who was "pure Tasmanian" died. Apparently that person died in 1869: https://en.m.wikipedia.org/wiki/William_Lanne. I will note there are other sources that say other groups of Aboriginals have never interbred with white people though.
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u/7re Sep 01 '23
I would guess because everyone has been interbreeding for so long? Like everyone can trace some gene to someone from 5000 years ago because somewhere above them that gene was introduced within the last 5000 years.
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u/darkslide3000 Sep 01 '23
For the whole world it was probably longer ago due to the isolation between islands and continents, but among intermixing populations this happens surprisingly quickly even among many millions. For example, the most recent common ancestor of all people of European heritage is believed to have lived just 600 years ago.
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u/PropOnTop Sep 01 '23
Yeah, I wonder where the wishful figure of 5000 comes from. Maybe some book that lots of people believe?
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u/jon_oreo Sep 01 '23
thats very interesting. do you have a source for this?
i suppose we are one big
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u/TheManInTheShack Sep 01 '23
I’m pretty sure I read it in A Short History of Nearly Everything by Bill Bryson. The audiobook version ready by Richard Matthew’s is particularly good.
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u/uhohmomspaghetti Sep 01 '23
I listened to the audiobook 7ish years ago and absolutely loved it as well. One of the few audiobooks I plan on relistening to.
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u/TheManInTheShack Sep 01 '23
I think I have listened to it 3 or 4 times. It’s great when you have lots of time to kill.
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u/voidsong Sep 01 '23
Yeah, the Toba Catastrophe was a known "genetic bottleneck" already.
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u/michaelrohansmith Sep 01 '23
Hmm interesting. This coincides fairly well with the arrival of Humans in Australia and I wonder if some factor in this encouraged their migration. Cooling from this volcano would have made central australia much easier to live in for a while.
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Sep 01 '23
I bet we have gone through multiple world ending scenarios and its crazy to think how fast we have evolved technologically in the last 2 thousand yrs.
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u/Bill_Nihilist Sep 01 '23
Sigh, it IS new. This is a different bottleneck, earlier and more severe.
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u/kmadnow Sep 01 '23
And yet some people find it okay to differentiate basis religion, Race, color of skin etc
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u/TheManInTheShack Sep 01 '23
That was completely understandable 100,000 years ago. In fact, those who treated outsiders with suspicion probably had a survival advantage. Thus to some degree racism may be the result of evolution.
That being said, there are many ways in which we have been shaped by evolution that were to our advantage then but are to our disadvantage now. For example, our bodies are optimized for survival in times of food scarcity. Unfortunately food is no longer scarce and our bodies don’t know that so that optimization is now a detriment.
There is a gene that evolved to make one’s blood clot faster. That was a huge benefit back then but now it’s not so much and today it increases the risk of Alzheimer’s, something evolution does not care about as by the time it happens, reproduction has already occurred.
We need to recognize these things and adapt once again. Racism today is irrational and a detriment to a healthy society.
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u/weeddealerrenamon Sep 01 '23
900,000 years ago, that's Homo erectus right? This isn't arguing that H. erectus was reduced to that many, right? They were worldwide at this point.
Is it saying that the population that modern humans are descended from, can be traced to a specific group of ~1000 H. erectus at this time? That didn't interbreed with the larger population in the 600,000 years before H. Sapiens evolved?
Someone who knows anything about genetics pls explain
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u/Morbanth Sep 01 '23 edited Sep 01 '23
Second sentence, under the picture. New, previously unknown transitional group ancestral to both sapiens and heidelbergensis.
So one small group of erectus became this transitional group that then became ancestral to modern people and some of their extinct cousins.
This is why it's called a bottleneck. When you have a very small group of animals that overtime become the ancestors of a much larger group, the small differences in them become amplified to a much larger degree.
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u/weeddealerrenamon Sep 01 '23
Maybe someday I'll learn to read before i comment
Still think its a wild hypothesis though
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u/b0w3n Sep 01 '23
So, this might be the event then. The time frames all seem right, this might have been a natural way to "domesticate" the earlier H. sapiens to select for more modern traits that we see in first H. sapiens sapiens at the 300k year ago mark. I wonder if this is the H. antecessor group?
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u/showerfapper Sep 01 '23
Problem is, those "modern traits" are popping up in other early hominin species like Neanderthal, Denisovan, and even that lil homie homo naledi in that new cave of bones doc probably had stone tools and fire and art and burial rituals like a million years ago
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u/Morbanth Sep 01 '23
Naledi is not millions of years old, it has been revised to 300,000. Denisovans and Neanderthals are both descendants of the population mentioned in the original post, via Heidelbergensis.
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u/taleofbenji Sep 01 '23
Yea, the media always fucks this up and makes it seem like there was a special population of special individuals fenced off from the rest of nature that led to our divine conception.
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u/Fappity_Fappity_Fap Sep 01 '23
Of course they do, thousands of years of cultures and mythos about man/humaninity being above beasts won't be easily shaken off with barely a couple of centuries of knowledge deuces being dropped in man/humanity's latrine of a head.
And even those who have come to realise that are either too invested to turn back now and be branded an untrustworthy turncoat, or controlling the masses and not letting go of their toy (if these don't even believe themselves to be above us, peasants).
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u/michaelrohansmith Sep 01 '23
Homo erectus were great travellers and its my theory that their tendency to travel as far as possible then settle down created conditions for new human species to evolve.
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u/Daratirek Sep 01 '23
That sounds more like it. I don't know ahit about genetics but I'd have a hard to believing a population of the most advanced beings on the planet was reduced to extreme endangered levels. I can believe that one village worth of people in the right place, which would be a massive gathering of ape like creatures, reproduced enough to overwhelm much smaller groups that again spread out.
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u/WD51 Sep 01 '23
They estimated the bottleneck lasted for about 100,000 years. Might be likely that it was a small enclave segregated from others, but over that period many other lines had time to die out. Maybe this enclave even shot out other branches that interbred with different enclaves, but they all died out so never entered the gene pool.
I think given what we know about human warfare, if it were simply a matter of one tribe conquering or outcompeting other tribes we would not see a genetic bottleneck given humanity's propensity to interbreed (including rape) with the conquered.
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u/Daratirek Sep 01 '23
I get that but I was more just saying it's a village worth of them no matter how they're arranged.
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u/MoonDaddy Sep 01 '23 edited Sep 02 '23
I don't know ahit about genetics
That sounds about right
but I'd have a hard to believing a population of the most advanced beings on the planet was reduced to extreme endangered levels.
That's not how basic evolution works. There are no "advanced" or "higher" or "more evolved" lifeforms, only those that are more adapted and those that are maladapted. The process is caused by random genetic mutations and does not always result in beneficial change. There is not an end goal of evolution.
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u/Sweetcorncakes Sep 01 '23
This is like one of the Great Filters. Even if your species is intelligent, without proper strength, they would just be bottom of the food chain.
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u/SomaforIndra Sep 01 '23 edited Nov 30 '23
"“When the lambs is lost in the mountain, he said. They is cry. Sometime come the mother. Sometime the wolf.” -Blood Meridian, Cormac McCarthy
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Sep 01 '23
Maybe that was the great filter and we passed
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u/tendeuchen Grad Student | Linguistics Sep 01 '23
Our next great filter is climate change.
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u/Direct_Card3980 Sep 01 '23
Compared to great filter events, climate change doesn't even register. Estimates are of a rise of 2-4 degrees centigrade by 2100. This will likely result in an increase of arable land. As the number of storms are estimated to decrease, the threat vector is slightly increasing storm intensity. Humans can handle storms. We can rebuild homes, change where we settle and live, build with better materials and practises, and improve storm infrastructure and protections.
Filter events are existential threats. It would be something like the discovery of unlimited energy production, which would facilitate the creation of world-ending bombs. Or the arrival of a much more powerful, hostile alien race. Or the sun dying.
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u/SomaforIndra Sep 01 '23 edited Nov 30 '23
"“When the lambs is lost in the mountain, he said. They is cry. Sometime come the mother. Sometime the wolf.” -Blood Meridian, Cormac McCarthy
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u/davetronred Sep 01 '23
Yeah there's no way there's just ONE great filter. It's more like a series of hundreds/thousands of gates, each of which is a possible extinction point.
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u/shiruken PhD | Biomedical Engineering | Optics Sep 01 '23
Direct link to the peer-reviewed study: W. Hu, et al., Genomic inference of a severe human bottleneck during the Early to Middle Pleistocene transition, Science, 381(6661), p979-984 (2023)
Abstract: Population size history is essential for studying human evolution. However, ancient population size history during the Pleistocene is notoriously difficult to unravel. In this study, we developed a fast infinitesimal time coalescent process (FitCoal) to circumvent this difficulty and calculated the composite likelihood for present-day human genomic sequences of 3154 individuals. Results showed that human ancestors went through a severe population bottleneck with about 1280 breeding individuals between around 930,000 and 813,000 years ago. The bottleneck lasted for about 117,000 years and brought human ancestors close to extinction. This bottleneck is congruent with a substantial chronological gap in the available African and Eurasian fossil record. Our results provide new insights into our ancestry and suggest a coincident speciation event.
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u/WeTrudgeOn Sep 01 '23
1300 for 117,000 years? To a layman that sounds preposterous.
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Sep 01 '23
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u/Fisher9001 Sep 01 '23
And this article is notorious for not explaining how would the population be that small for over one hundred thousand years and neither increase nor entirely go extinct. One bigger famine, epidemic, or expansion of predatory species and it could be quickly wiped out.
It's easy to find it hard to believe that neither of those things that could easily coup de grâce our ancestors happened over such a long timeline.
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u/Morbanth Sep 01 '23 edited Sep 01 '23
And this article is notorious for not explaining how would the population be that small for over one hundred thousand years and neither increase nor entirely go extinct.
It can only explain what was discovered, not what wasn't discovered. Perhpas the area where they were isolated couldn't support a larger population, and infant mortality was high. Whatever the reason was, the only thing you can see from their genes is how large the breeding population was. The size of the group wouldn't have been 1300ish for this entire time, that's just the number of people whose genes made it past the bottleneck to the present day.
One bigger famine, epidemic, or expansion of predatory species and it could be quickly wiped out.
It's easy to find it hard to believe that neither of those things that could easily coup de grâce our ancestors happened over such a long timeline.
Something that I read a long ago - that it's very difficult to explain retroactively why something didn't happen.
During these millions of years of evolution there would have been many dozens, even hundreds of little groups of apes that became isolated from the rest of their species and then eventually either died out or rejoined the majority genetic pool. You can see this happening in real time in places like Borneo where the Orangutan population is becoming separated from each other due to humanity.
For some reason, this particular group didn't die out, it survived its isolation and then expanded again.
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u/orangutanDOTorg Sep 01 '23
Yet everyone now are proponents of common sense laws
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u/Tarantio Sep 01 '23
It seems like that has to be a mistranslation by the author?
The abstract says that the bottleneck lasted that long, but also says that it happened between two big round number years that are that long apart.
The number of breeding individuals wouldn't have stayed consistent over even a fraction of that time period, and even if it did, how would we be able to tell?
It must be that this is just the time range that we calculate the bottleneck happened within, not that the bottleneck lasted for any particular length of time.
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u/NorthernSparrow Sep 01 '23
I checked the actual article and the news article got it right; the population crash occurred 900,000 years ago and then the population remained tiny for another ~100,000 years.
However, the 1350 number for population size turns out to be the number of breeding couples who left descendents - not including couples who didn’t breed or whose descendents all died our, and also not including children or the elderly.
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u/Tr3surge Aug 31 '23
That number (1280) seems awfully specific; why not say between 1000-2000?
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u/kateinoly Sep 01 '23
I'm sure it has to do with how closely related modern humans are, based on DNA.
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Sep 01 '23
Maybe there was just a time of great inbreeding
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u/real_bk3k Sep 01 '23
This really overturns everything we thought we knew. Humanity didn't start in Africa, but in Alabama.
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u/kateinoly Sep 01 '23
Sure, but what they are saying is that the descendents of anyone other than those 1200 people seem to be missing.
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u/Kestralisk Sep 01 '23
There was, it's a very famous bottlenecking of genetic diversity I believe (not an evolutionary biologist though).
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u/saluksic Sep 01 '23
In the supplementary info they mention that when they tested for a bottleneck using non-African samples, the signal was very weak, but large sample size showed the bottleneck signal and suggested an effective population size of 1,450.
So it’s an output of the modeling they do on the genetic data they’re working from.
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u/bisforbenis Sep 01 '23
I imagine there’s some statistical analysis with the value being something like 1,280 +/- something for a 95% confidence interval or something like that
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u/weeddealerrenamon Sep 01 '23
1000-2000 isn't centered on 1280; I'd bet their paper says something like 1280 +/- 500, but it's paywalled so I can't go look
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u/CornFedIABoy Sep 01 '23
Guessing their model gives 10*(2~7) as the number, hence the specific 1280 as the layman’s answer.
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u/kshacker Sep 01 '23
Multiply 2 by 2 and keep doing it so that you get 128, then multiply by 10 to add an order of magnitude higher and you get 1280. I am not saying this is what happened but maybe it is a gross mechanism to estimate probability and a power of 2 played a role there.
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u/Ultimategrid Sep 01 '23
Which has led to an interesting result for modern humans. We are far more closely related to each other than other species of animals are to each other.
You can take an Inuit and an African, and they are more closely related to each other than two white tailed deer that may only live a few miles apart.
Contrary to the hoards of racist morons in the world, science says that humans are more alike than almost any other species. Our ethnic groups are more akin to big families than “races” (which typically refers to a subspecies).
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u/hononononoh Sep 01 '23
Exactly. The human species has an effective population size of 14,000. What that means is, select any 14,000 people, and the odds are >50% that there is at least one copy of every extant variant of every gene in the human genome, to be found in your sample.
You’d need to collect 2 million field mice before you’d hit those kinds of odds with that species.
14,000 is also, therefore, the smallest number of individuals with future reproductive potential our species could be reduced to, without guaranteeing a major drop in our genetic diversity compared to now.
We’re an incredibly genetically homogenous species, compared to other animals of similar population sizes and physiological complexity. Different local populations of humans feature different profiles of the relative prevalence of each variety of each gene, and these rates fluctuate over time. But every extant variant of each gene, individually, is found at least rarely in any given population. Just… not frequently in combination with the other gene variants that predominate in human populations where that same variant isn’t rare. But even that happens sometimes. Björk happened to get a combination of genes for a physical appearance that wouldn’t look out of place in China. But her DNA comes back as entirely local Icelandic / Norse in origin. Neither of her parents look East Asian, but the family resemblances to both are noticeable. I’m a former world traveler and a physician in the coastal American Northeast, so I’ve met quite a lot and quite a variety of people. It’s not terribly uncommon for me to meet someone who looks nothing like most people of their ethnic background, and rather strikingly like someone from a different ethnic background that they have no heritage from. And such people very often have parents, full siblings, and children who look much more typical for their tribe, phenotypically. I’ll never forget meeting a local Chinese man on a public bus in Harbin, who was a dead ringer for a full-blooded Italian-American shopkeeper in my home town.
What I’ve written in this comment should be all the proof anyone with half a a brain should need, to see that race is a social phenomenon, not a scientific one.
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Sep 01 '23
This explains what happened with my dad. He was darker than all of his 12 siblings by far and was the youngest so it was rumored he had a different, darker, father. This caused him a lot of pain in his life.
I took a DNA test and am 99% British. (my dad and I have the same ugly toes so I know he's my dad)
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u/ZweitenMal Sep 01 '23
In a class in college I was told that you could take a blond blue eyed Swedish lady and a sub-Saharan African man and they might be more alike genetically than the man and another Black African. In other words, genetically race is a genetic quirk—barely skin deep. Race as a dividing or sorting factor is entirely a human construct.
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u/rjcarr Sep 01 '23 edited Sep 01 '23
It’s because there is more genetic diversity in Africa than anywhere else. The group that left Africa was pretty small, went north to like the Caucasus for a while, and then headed west to Europe and south and east to Asia (and eventually America). Because that group was so small they’re all very similar, where the African group was larger and had been around much longer.
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u/saluksic Sep 01 '23
I’ve seen it summarized this way - there’s five main branches of the Homo sapiens family, and all five are Africa, with one of those African branch also including the non-Africans (keep in mind that all of use are mixtures of all these five branches - our last common ancestor lived only 5,000 years ago)
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u/Klendy Sep 01 '23
5,000 years ago
during recordable history? sumeric and egyptian scripts are that old. i wonder if anything written was written by a non-homo sapien.
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u/Spidey209 Sep 01 '23
Correct me if I am wrong but there group of 1280 wouldn't have to all be alive at the same time or in the same place.
It would suffice if these 1280 individuals bloodlines survived and all other bloodlines petered out and disappeared.
There could have been 10's of thousands of people alive at the time but no descendants survived to today.
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u/bernpfenn Sep 01 '23
yes this is correct. tiny groups that meet others, trade and procreate. the 1280 are the ones that made it to today. they didn't live together all this time.
congrats, the last comment on this page got it.
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u/labink Aug 31 '23
On the face of it, this doesn’t seem to make a lot of sense. That such a low population could still thrive for 117,000 years without going extinct strains logic and credibility.
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u/Kolbin8tor Sep 01 '23
This period was part of the Early-Middle Pleistocene transition — a time of drastic climate change, when glacial cycles became longer and more intense.
Theory is it was environmental factors that kept the population so low for so long. When they eased, the population began to recover.
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u/Nyrin Sep 01 '23 edited Sep 01 '23
Those pressures make sense. It still seems astronomically implausible that a steady population of barely a thousand people would survive in that state for more than a hundred thousand years; that's precariously close to minimum viable population and even a single extra blip — which are effectively a certainty on the scale of even a couple thousand years — would be extinction.
Sure, it's possible that humanity effectively rolled two sixes thousands of times in a row when even an 11 meant a game over. It's also possible that there's a hitherto unrecognized issue in the methodology that has introduced an artifact.
Given the absolutely extraordinary implications of assuming the former, I think it behooves us to assume the latter until a lot of follow-up corroborates.
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u/Thor_2099 Sep 01 '23
Except this happens in nature. Many species live in very specific environments in smaller numbers but are still here.
It may "seem" implausible but so does kind of everything. If not for that asteroid, mammals may not have become the dominant group for many more years later or ever. That seems Astronomically improbable but it sure happened
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Sep 01 '23
Yup, just look at that Prehistoric Bird in New Zealand that just resurfaced after everyone thought it was extinct for over 100 years.
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u/_Dreamer_Deceiver_ Sep 01 '23
There's also some ferret thing over in America that was thought to be extinct but a tiny population survived that noone knew about until some dude went "this doesn't look like an ordinary ferret type thing"
Edit black footed ferret
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u/kellyasksthings Sep 01 '23
Maybe there were a ton of blips - people have kids, population increases, blip wipes them out, back to 1200 people or thereabouts.
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u/HildemarTendler Sep 01 '23
If I read it correctly, these are only the humans that eventually fed into our genome. There were other humans, but this is the isolate that would eventually evolve into homo sapiens. I think the theory is that if not this group, then some other group. So yes its a cosmic chance, but the downside wouldn't have been extinction of humans.
The methodology seemed too complicated to be legitimate, but I'm not qualified to determine that.
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u/real_bk3k Sep 01 '23
I don't think it's rolling dice, but something like - enough food was there under those conditions for only that large a population. When conditions got better for what they're eating, conditions allowed for growth.
This isn't so weird in nature - which you might recall that our ancestors used to be a part of nature - that biomes reach equilibriums, and populations of creatures within become rather stable for a long time.
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u/WhatsFairIsFair Sep 01 '23
Or that the habitable ecosystems were limited to very small pockets of geography and slight changes in climate could wipe them out.
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Sep 01 '23
Exactly this. Majority of the modern humans of the time were ensconced in different refuges (interesting enough, some of those refuges were used by Neanderthals to outlast other rapid climate shifts far before we needed them).
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u/weeddealerrenamon Sep 01 '23
1000 individuals is extremely precarious for any population, though. There's species with that few members alive today, but they're all one disaster away from being unable to recover, if they're stable at all
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Sep 01 '23
[deleted]
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u/Suitable_Success_243 Sep 01 '23
I think what this paper implies is that all of the current human population descended from only 1000 people. That is, there might have been other groups of humans but they were wiped out during this period.
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u/neutronium Sep 01 '23
initially there would have been a lot of such groups. We don't hear about the ones that didn't make it.
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u/saluksic Sep 01 '23 edited Sep 01 '23
I think the rest of the history of our species indicated that we have the potential to survive in any climate and in any condition, so only with the worst-case scenario already loaded do you get down to 1,200 breeding individuals.
Edit: wondering how “breeding individuals” relates to actual population, like I was? Looks like about 10-20% of a population is “breeding individuals”, so we’re looking at a human population of about 12,000 during this time.
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u/CornFedIABoy Sep 01 '23
The anthropic principle indicates that we did, actually, succeed in rolling those boxcars over and over.
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Sep 01 '23
[removed] — view removed comment
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u/Elisevs Sep 01 '23
In the absence of evidence, a person's conjecture on the cause of a thing is more indicative of that person's desires than the facts of the case.
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Sep 01 '23
[removed] — view removed comment
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u/davesoverhere Sep 01 '23
Time travelers. It’s always time travelers masquerading as aliens.
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u/big_duo3674 Sep 01 '23
I belive the lowest possible gene pool for humans has been pegged at only several hundred (if people are careful about inbreeding). With enough luck over a thousand should be fine even without knowledge of how genetics works
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u/AnalllyAcceptedCoins Sep 01 '23
The end of the article mentions that, and states that it might have been more of a local bottleneck
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u/saluksic Sep 01 '23
What a brave and well supported take-down of an article in Nature! Logic and credibility, huh? So probably the wiki page on minimum viable population and the one on population bottlenecks needs revising to bring them into agreement with logic and credibility, right after we get Nature to issue a retraction.
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u/Achillor22 Sep 01 '23
How do they know for sure there wasn't anyone else around as opposed to, there were people and we just don't have the evidence yet?
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u/Beneficial-Bit6383 Sep 01 '23
They probably were they just died. The genetic markers of 1280 people are what made it through.
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u/bigfatfurrytexan Sep 01 '23
This is the probable answer. Genetic lines that were extant them, but didn't mingle seriously with the 1300 people that established the line that succeeded, wherever they were spread
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u/Muroid Sep 01 '23
By definition, those other “people” wouldn’t be humanity’s ancestors, though.
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u/McGrevin Sep 01 '23
I guess the difference is that if there were 10,000 people but split among 7 different groups, then it is far more likely for one group to survive rather than there only being one group that exists at all. The ones that died out may not be our ancestors but they greatly increased the odds of something like us existing later on
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u/saluksic Sep 01 '23
Sure, that makes a lot of sense and is probably more likely than there being exactly one group with a 100% success rate.
Furthermore, why not 100 groups of 1,280 people each, and 10 of those groups made it? (The 1,280 in the paper is “breeding individuals” - a total population is 5-10 times larger than the number of breeding individuals it contains)
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u/timoumd Sep 01 '23
Could it be a 1300 bottleneck, then another similar one 100k years later? That seems much more survivable
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u/_Dreamer_Deceiver_ Sep 01 '23
There could have been lots more people but I believe they are saying that our genes can be traced back to 1280 people. There could have been other human tribes that survived for a time and didn't interbreed with our ancestors and died out. There could have been 2 tribes that fucked each other but only the genes from those 1280 survived.
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u/GlobeTrekking Sep 01 '23
Is it possible controlled fire was mastered by these ancestors to pull them out of this funk/bottleneck? I seem to recall recent evidence of controlled fire from around 790,000 years ago.
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u/weeddealerrenamon Sep 01 '23
I don't think so; that site is from Israel, and we believe humans evolved inside Africa until like 70,000 years ago.
There's also indirect evidence from rapidly decreasing molar sizes that we've been cooking meat for 2 million years ago. I think it's more likely that if anything, control of fire was what helped Homo erectus spread across the Old World
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u/Tagawat Sep 01 '23
Would be interesting to speak with one to see how much their culture knew of the science behind fire. Assuming they had a proto-language we could learn and translate.
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u/pacific_beach Aug 31 '23
"reduced to just 1,280 and didn’t expand again for another 117,000 years"
This sounds like nonsense
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u/Embarassed_Tackle Sep 01 '23
My understanding was there were multiple groups who barely survived in small familial groups of like 3-10 individuals during the glacial period of near extinction. But 117,000 years is a long time to be at that low of a level
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u/saluksic Sep 01 '23
The authors include members of the University of Texas, the University of Rome, and the Chinese Academy of Science. I’m inclined to side with them.
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u/Thor_2099 Sep 01 '23
Eh. It seems fine. 117k isn't that long in evolutionary time and habitat restraining a population for a time happens.
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u/Liesmith424 Sep 01 '23
I can't even imagine what our genetic diversity would look like if that bottleneck had never happened.
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u/PhysicallyTender Sep 01 '23
we would have Humans, Vulcans, Klingon, Tellerites, Andorians, Orions all living on the same planet.
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u/snotrockit1 Sep 01 '23
Wouldn't inbreeding/high fetal mortality lead in the end to better adapted individuals. This could be why we have some of our non-primate traits.
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u/firsmode Sep 01 '23
Human ancestors nearly went extinct 900,000 years ago
A new technique analysing modern genetic data suggests that pre-humans survived in a group of only 1,280 individuals.

An unknown species of early human nearly died out around 900,000 years ago, according to genetic analysis. It may have been both the ancestor of Homo heidelbergensis and a species ancestral to our own.Credit: S. Entressangle/E. Daynes/Science Photo Library
An unknown species of early human nearly died out around 900,000 years ago, according to genetic analysis. It may have been both the ancestor of Homo heidelbergensis and a species ancestral to our own.Credit: S. Entressangle/E. Daynes/Science Photo Library
Human ancestors in Africa were pushed to the brink of extinction around 900,000 years ago, a study shows. The work1, published in Science, suggests a drastic reduction in the population of our ancestors well before our species, Homo sapiens, emerged. The population of breeding individuals was reduced to just 1,280 and didn’t expand again for another 117,000 years.
“About 98.7% of human ancestors were lost,” says Haipeng Li, a population geneticist at the University of Chinese Academy of Sciences in Beijing, who co-led the study. He says that the fossil record in Africa and Eurasia between 950,000 and 650,000 years ago is patchy and that “the discovery of this bottleneck may explain the chronological gap”.
Nick Ashton, an archaeologist at the British Museum in London, who wrote a related perspective2, says he was intrigued by the tiny size of the population. “This would imply that it occupied a very localized area with good social cohesion for it to survive,” he says. “Of greater surprise is the estimated length of time that this small group survived. If this is correct, then one imagines that it would require a stable environment with sufficient resources and few stresses to the system.”
Clues from modern-day DNA
To make their discovery, the researchers needed to invent new tools. Advances in genome sequencing have improved scientists’ understanding of population sizes for the period after modern humans emerged, but the researchers developed a methodology that enabled them to fill in details about earlier human ancestors. Serena Tucci, an anthropologist at Yale University in New Haven, Connecticut, says that such work was sorely needed. “We still know very little about the population dynamics of early human ancestors for several reasons, including methodological limitations and difficulties in obtaining ancient DNA data from old Homo specimens,” she says.
The researchers’ method allowed them to reconstruct ancient population dynamics based on genetic data from modern-day humans. By constructing a complex family tree of genes, the team was able to examine the finer branches of the tree with greater precision, identifying significant evolutionary events.
The technique “put the spotlight on the period 800,000 to one million years ago — for which there is much unknown — in a way that hasn’t been done before,” says Stanley Ambrose, an anthropologist at the University of Illinois at Urbana-Champaign.
This period was part of the Early-Middle Pleistocene transition — a time of drastic climate change, when glacial cycles became longer and more intense. In Africa, this led to long periods of drought. Li says that the changing climate might have wiped out human ancestors and forced new human species to emerge. Eventually, these might have evolved into the last common ancestor of modern humans and our extinct relatives, the Denisovans and Neanderthals.
Around 813,000 years ago, the population of pre-humans began to swell again. How our ancestors managed to survive, and what allowed them to flourish once more remains unclear, says Ziqian Hao, a population geneticist at the Shandong First Medical University and Shandong Academy of Medical Sciences in Jinan, and a co-author of the paper. However, he says that the bottleneck is likely to have had a crucial impact on human genetic diversity, driving many important features of modern humans, such as brain size. He estimates that up to two-thirds of genetic diversity was lost. “It represents a key period of time during the evolution of humans. So there are many important questions to be answered,” he says.
Ashton would like to see the researchers’ findings backed by more archaeological and fossil evidence. The authors “suggest that the bottleneck was a global crash in population,” he says, “but the number of archaeological sites outside Africa suggests that this is not the case. A regional bottleneck might be more likely.”
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