How a new method of inferring ancient population size revealed a severe bottleneck in the human population which almost wiped out the chance for humanity as we know it today.
An unexplained gap in the African/Eurasian fossil record may now be explained thanks to a team of researchers from China, Italy and the United States.
[…]
These findings indicate that early human ancestors went through a prolonged, severe bottleneck in which approximately 1,280 breeding individuals were able to sustain a population for about 117,000 years. While this research has illuminated some aspects of early to middle Pleistocene ancestors, there are many more questions to be answered since uncovering this information.
[…]
Reasons suggested for this downturn in human ancestral population are mostly climatic: glaciation events around this time lead to changes in temperatures, severe droughts, and loss of other species, potentially used as food sources for ancestral humans.
The African hominin fossil gap and the estimated time period of chromosome fusion is shown on the right. Credit: Science (2023). DOI: 10.1126/science.abq7487
An estimated 65.85% of current genetic diversity may have been lost due to this bottleneck in the early to middle Pleistocene era, and the prolonged period of minimal numbers of breeding individuals threatened humanity as we know it today.
What was going on from 1,000-800 ka that may have nearly wiped out our ancestors? Temperatures plunged, glaciers and ice sheets started expanding, sea levels fell & began oscillating with glacial cycles and atmospheric CO2 dropped to its lowest level in 400 million years.
Kenneth G. Miller et al. ,Cenozoic sea-level and cryospheric evolution from deep-sea geochemical and continental margin records.Sci. Adv.6,eaaz1346(2020).DOI:10.1126/sciadv.aaz1346
There is a documentary that discusses mitochondrial DNA that shows this bottle neck but contributes the decline in humans to volcanic activity. The climate was erratic for a long period disrupting population growth.
Earth had been in Ice Age conditions for nearly 2 million years and then a little bit colder breaks the camel’s back in a place less affected like Africa by cooling. Maybe most humans lived near the coastline and of course what is left of them now is under 80m of ocean.
From the article: “These findings indicate that early human ancestors went through a prolonged, severe bottleneck in which approximately 1,280 breeding individuals were able to sustain a population for about 117,000 years.”
I’m a little skeptical of those numbers, too.
Are they saying humans sustained a population of 1,280 breeding pairs for 117,000 years?
I would think that if these humans survived, then they would increase their numbers as they adapted to the situation.That 117,000 years is a long time for a human population to remain static.
No, the number of early humans was very small. My family still bears a grudge against the Ug’s dad, who borrowed my great great great great…great grandfather’s club, and brought it back cracked, and then had the gall to pantomime that it was that way when he got it.
“approximately 1,280 breeding individuals”
Let’s not accept nonsense numbers to score a few points. There is not enough data to support that inference.
It is all invented. Apparently, the Super Toba eruption only affected humans. All the rest of the species did just fine. Pretty weak these ancient humans.
“These findings indicate that early human ancestors went through a prolonged, severe bottleneck…”
I’m certainly no scientist but I doubt there has ever been such a bottleneck. The lack of fossils in many areas for long periods just may indicate poor conditions for fossil formation along with a lack of needed investigation. Africa is several times larger than America. The idea that there was a bottleneck with that vast landscape, to me, is absurd.
The idea of the bottleneck is not new data and is supported by DNA evidence. You’ve got to look at in reverse – our entire species today are the ones that survived; there may have been others but they died out and didn’t contribute their DNA to modern humans.
Catastrophic theories abound, and so do fossil gaps. Catastrophism as a geological theory was put to rest in the 19th century, but it still raises its ugly head in other disciplines from time to time.
Genetic bottlenecks indicate present population descends from a small subgroup, not that at the time a catastrophe took place. It is the well-known founder effect.
If the finding is correct, the most likely explanation is that a subpopulation evolved under limited genetic exchange with the rest of the species for 100,000 years and acquired an advantage that made them substitute the rest. This doesn’t require a few individuals to survive, just a few individuals to contribute their genes, the total population might be the same all the time.
It is against our knowledge of biology that a species will not expand to the maximum its ecological niche allows in a few generations. How do you explain Homo’s ecological niche shrunk globally so much for so long, yet it didn’t affect other species? The mixture of anthropocentrism and catastrophism is very hard to eradicate and is very common, not only among the general population (and in this blog) but also among scientists.
When looking from present genetic frequencies toward the past we cannot know what happened to those that didn’t contribute, so all the rest is invented.
Len Werner
September 2, 2023 7:06 am
What happens to the authors’ conclusions if it is assumed that for a period of time a cultural norm was to dispose of human bodies in a fashion that didn’t generate fossils? For example, for a period of time in Christian history there is a distinct lack of fossils of witches.
If I can reverse John Oliver’s comment, simply because it makes more sense to me–‘You don’t know what you can’t know’.
Instead of CO2 mesmerizing, have they any data for total atmospheric pressure over these timescales? Dynamic total air pressure changes on these short timescales should worry everyone.
For some strange reason constant pressure is assumed over tens of millions of years. Have we a case of :
Humans easily adapt to changing ambient air pressures . . . witness humans not only surviving, but prospering, in cities and villages 10,000 feet or more above sea-level* (4.6 psi or lower than sea-level pressure) and the fact that divers in oceans and lakes can go down to depths of more than 200 feet without pressure suits, where external pressures are about 104 psia, or more than seven times sea-level pressure.
*For example, Leadville, Colorado, is a city at elevation 10,200 feet, and La Paz, Bolivia, is a city at 11,900 feet elevation.
Caleb Shaw
September 2, 2023 12:23 pm
I think there will be future discoveries which demonstrate our current grasp of genetics has some major flaws. People act as if it is perfected but it leads to some curious conclusions.
For example, a breed of dog has existed in Peru for a thousand years. It has a strange trait, in that the dogs are hairless. However, when you compare the chromosomes of a modern hairless dog with the mummified remains of a hairless dog that lived a thousand years ago, one sees no relationship exists between the two animals. Is it true they are not related, or perhaps we should be humble and realize that, over what may have been as many as five hundred generations, “stuff happens????”
However, when you compare the chromosomes of a modern hairless dog with the mummified remains of a hairless dog that lived a thousand years ago, one sees no relationship exists between the two animals. Is it true they are not related,
Apart from both being Canis familiaris, that is. That’s going to give well over 99.9% genetic commonality.
Hell, Canis familiaris can breed with Canis lupus and produce fertile offspring, so even different species can have a vast amount in common.
Parallel evolution may well produce similar traits through different alleles, which is probably the case with the different breeds of bald dogs.
Fran
September 2, 2023 3:13 pm
I will withhold judgment until someone who understands the methodology explains. Is it possible that this bottleneck is the same signature that others have called the Toba eruption bottleneck 78ky ago? Estimates for population are about the same for both and both must be making all sorts of assumptions about mutation rates. One puts the bottleneck in the homo erectus period and the other in essentially modern human times.
Kit P
September 2, 2023 6:42 pm
Do I have this correct? Sometime in the past we almost stopped existing and as the graph shows it has something to do with CO2 and sea level.
Therefore if I live in Califonia, I should buy an BEV and pretend it is fueled with my roof top PV (made with China slave labor coal) and not an out of state coal plant.
From the above article: “An estimated 65.85% of current genetic diversity may have been lost due to . . .”
I absolutely love that extreme precision (one part in 6,500) for an “estimate”!
Likewise, “These findings indicate that early human ancestors went through a prolonged, severe bottleneck in which approximately 1,280 breeding individuals were . . .”
That’s a precision of one part in 130 (i.e., better than 1%)
Leaves me wondering what proxy they used to support these precise calculations, given it is focused on a time interval some one million to 800,000 years ago?
IOW, bottom line: garbage in, garbage out.
Crisp
September 10, 2023 12:49 am
Firstly, there were no humans that long ago, only hominids. We had not even separated from Neanderthals yet and did not appear for another 600k years.
Secondly, this is based on that now-dreaded thing, a computer model called FitCoal. They claim an accuracy of better than 10exp-10. This is idiotic. They clearly mean precision, not accuracy, but even that is wrong. They appear not to understand “significant figures” and the limits the data places on that. Patrick Frank would have fun pointing their total failure to address error accumulation in their calculations over that vast timespan.
Was the World Economic Forum, WEF, involved with that bottleneck?
Zee great reset?
There is a documentary that discusses mitochondrial DNA that shows this bottle neck but contributes the decline in humans to volcanic activity. The climate was erratic for a long period disrupting population growth.
Earth had been in Ice Age conditions for nearly 2 million years and then a little bit colder breaks the camel’s back in a place less affected like Africa by cooling. Maybe most humans lived near the coastline and of course what is left of them now is under 80m of ocean.
I like the way you think.
So we actually need the next glaciation to study that period of human prehistory, if the salt water left anything to be studied.
I just can not believe they can know such numbers to such accuracy.
From the article: “These findings indicate that early human ancestors went through a prolonged, severe bottleneck in which approximately 1,280 breeding individuals were able to sustain a population for about 117,000 years.”
I’m a little skeptical of those numbers, too.
Are they saying humans sustained a population of 1,280 breeding pairs for 117,000 years?
I would think that if these humans survived, then they would increase their numbers as they adapted to the situation.That 117,000 years is a long time for a human population to remain static.
Maybe I’m misinterpreting what they are saying.
No, the number of early humans was very small. My family still bears a grudge against the Ug’s dad, who borrowed my great great great great…great grandfather’s club, and brought it back cracked, and then had the gall to pantomime that it was that way when he got it.
“approximately 1,280 breeding individuals”
Let’s not accept nonsense numbers to score a few points. There is not enough data to support that inference.
I said I was a little skeptical of the numbers, didn’t I?
What points do you think I am trying to score?
So many years of inbreeding and no problems while 1000 years of inbreeding under royals did so much damage.
Fewer breeding pairs.
There was the Super Volcano Toba about 74,000 years ago that may have resulted in a low human population….life was tough back then…really tough.
It is all invented. Apparently, the Super Toba eruption only affected humans. All the rest of the species did just fine. Pretty weak these ancient humans.
“These findings indicate that early human ancestors went through a prolonged, severe bottleneck…”
I’m certainly no scientist but I doubt there has ever been such a bottleneck. The lack of fossils in many areas for long periods just may indicate poor conditions for fossil formation along with a lack of needed investigation. Africa is several times larger than America. The idea that there was a bottleneck with that vast landscape, to me, is absurd.
The idea of the bottleneck is not new data and is supported by DNA evidence. You’ve got to look at in reverse – our entire species today are the ones that survived; there may have been others but they died out and didn’t contribute their DNA to modern humans.
Good thing the Endangered Species Act wasn’t around back then – we would have been wiped out.
You can’t know what you don’t know. so why do so many “ scientist” try state things so conclusively.?
I have always wondered if early man understood that if you go a certain direction it gets warmer or colder
If they could tell a temperature difference over the distances they could travel, then they were local differences and irrelevant.
Salute!
I am having trouble seeig the “bottleneck” on the chart- it is too busy with other stuff, and I am not sure about the date.
My ubnderstanding was way back humans got down to a ridiculous low number, and then rebounded.
Maybe another contributor could post a graphic showing the low point and a simple climate value…. a simple chart.
Gums sends…
Used-car sale strategies have pervaded science. Success is no longer to publish in a good journal, it is to become world news.
Catastrophic theories abound, and so do fossil gaps. Catastrophism as a geological theory was put to rest in the 19th century, but it still raises its ugly head in other disciplines from time to time.
Genetic bottlenecks indicate present population descends from a small subgroup, not that at the time a catastrophe took place. It is the well-known founder effect.
If the finding is correct, the most likely explanation is that a subpopulation evolved under limited genetic exchange with the rest of the species for 100,000 years and acquired an advantage that made them substitute the rest. This doesn’t require a few individuals to survive, just a few individuals to contribute their genes, the total population might be the same all the time.
It is against our knowledge of biology that a species will not expand to the maximum its ecological niche allows in a few generations. How do you explain Homo’s ecological niche shrunk globally so much for so long, yet it didn’t affect other species? The mixture of anthropocentrism and catastrophism is very hard to eradicate and is very common, not only among the general population (and in this blog) but also among scientists.
When looking from present genetic frequencies toward the past we cannot know what happened to those that didn’t contribute, so all the rest is invented.
What happens to the authors’ conclusions if it is assumed that for a period of time a cultural norm was to dispose of human bodies in a fashion that didn’t generate fossils? For example, for a period of time in Christian history there is a distinct lack of fossils of witches.
If I can reverse John Oliver’s comment, simply because it makes more sense to me–‘You don’t know what you can’t know’.
Instead of CO2 mesmerizing, have they any data for total atmospheric pressure over these timescales? Dynamic total air pressure changes on these short timescales should worry everyone.
For some strange reason constant pressure is assumed over tens of millions of years. Have we a case of :
Humans easily adapt to changing ambient air pressures . . . witness humans not only surviving, but prospering, in cities and villages 10,000 feet or more above sea-level* (4.6 psi or lower than sea-level pressure) and the fact that divers in oceans and lakes can go down to depths of more than 200 feet without pressure suits, where external pressures are about 104 psia, or more than seven times sea-level pressure.
*For example, Leadville, Colorado, is a city at elevation 10,200 feet, and La Paz, Bolivia, is a city at 11,900 feet elevation.
I think there will be future discoveries which demonstrate our current grasp of genetics has some major flaws. People act as if it is perfected but it leads to some curious conclusions.
For example, a breed of dog has existed in Peru for a thousand years. It has a strange trait, in that the dogs are hairless. However, when you compare the chromosomes of a modern hairless dog with the mummified remains of a hairless dog that lived a thousand years ago, one sees no relationship exists between the two animals. Is it true they are not related, or perhaps we should be humble and realize that, over what may have been as many as five hundred generations, “stuff happens????”
Apart from both being Canis familiaris, that is. That’s going to give well over 99.9% genetic commonality.
Hell, Canis familiaris can breed with Canis lupus and produce fertile offspring, so even different species can have a vast amount in common.
Parallel evolution may well produce similar traits through different alleles, which is probably the case with the different breeds of bald dogs.
I will withhold judgment until someone who understands the methodology explains. Is it possible that this bottleneck is the same signature that others have called the Toba eruption bottleneck 78ky ago? Estimates for population are about the same for both and both must be making all sorts of assumptions about mutation rates. One puts the bottleneck in the homo erectus period and the other in essentially modern human times.
Do I have this correct? Sometime in the past we almost stopped existing and as the graph shows it has something to do with CO2 and sea level.
Therefore if I live in Califonia, I should buy an BEV and pretend it is fueled with my roof top PV (made with China slave labor coal) and not an out of state coal plant.
This will save the human race.
From the above article:
“An estimated 65.85% of current genetic diversity may have been lost due to . . .”
I absolutely love that extreme precision (one part in 6,500) for an “estimate”!
Likewise,
“These findings indicate that early human ancestors went through a prolonged, severe bottleneck in which approximately 1,280 breeding individuals were . . .”
That’s a precision of one part in 130 (i.e., better than 1%)
Leaves me wondering what proxy they used to support these precise calculations, given it is focused on a time interval some one million to 800,000 years ago?
IOW, bottom line: garbage in, garbage out.
Firstly, there were no humans that long ago, only hominids. We had not even separated from Neanderthals yet and did not appear for another 600k years.
Secondly, this is based on that now-dreaded thing, a computer model called FitCoal. They claim an accuracy of better than 10exp-10. This is idiotic. They clearly mean precision, not accuracy, but even that is wrong. They appear not to understand “significant figures” and the limits the data places on that. Patrick Frank would have fun pointing their total failure to address error accumulation in their calculations over that vast timespan.