Some 900,000 years ago, humans nearly went extinct. According to the results of a genomics study published last year, modern humanity’s ancestors were reduced to a breeding population of barely 1,300 individuals in a devastating bottleneck that brought us to the very brink of annihilation. Now, a new study has found that a mass migration of humans out of Africa occurred at the same time.
It’s a discovery that confirms the previous dating of the population decline, and suggests that the two are linked to a common denominator; an event known as the Mid-Pleistocene Transition, in which Earth’s climate underwent a period of utter turmoil, wiping out many species. The movement of early humans into and across Europe and Asia from Africa is difficult to reconstruct. The best evidence we have consists of a sparse record of bones and mostly stone artifacts, which can be challenging to date. However, the evidence suggests that it wasn’t one event, but multiple waves of early hominids and human ancestors that packed up their lives and made long journeys into new environments.
Two recent studies have linked human migration to a population bottleneck, based on different types of analysis. A close reading of the human genome found that a population bottleneck caused a loss of genetic diversity some 900,000 years ago. A second study, published a few weeks later, studied early archaeological sites in Eurasia, and dated the bottleneck to 1.1 million years ago.
This discrepancy makes it challenging to identify the climate event that may have caused or at the very least contributed to the temporary drop in numbers, so geologists Giovanni Muttoni of the University of Milan and Dennis Kent of Columbia University embarked on an effort to narrow down the timing of the bottleneck. First, the researchers re-evaluated records of sites of early hominid habitation across Eurasia, and found a cluster of sites reliably dated to 900,000 years ago. In comparison, the dating on older sites used as evidence of a population bottleneck was more ambiguous and therefore disputable.
They compared their findings to marine sediment records, which preserve evidence of changes in the climate in the form of oxygen isotopes. Ratios of oxygen trapped in sediment layers indicate whether the climate was warmer or cooler at the time the minerals were deposited.
The genomic data and the dating of the hominid sites together suggest that the bottleneck and the migration were simultaneous. During the Mid-Pleistocene Transition, global ocean levels dropped, and Africa and Asia dried out, with large patches of aridity. Hominids living in Africa would have faced horrible conditions depriving them of food and water. Fortunately, with the falling sea level, land routes into Eurasia became available and they were able to skedaddle, according to the researchers’ model.
This is not to say, they carefully note, that hominids had not migrated previously. Rather that the population bottleneck in the ancestor of modern Homo sapiens and the migration thereof occurred at the same time as a result of the climate upheaval that was occurring some 900,000 years ago.
“We suggest that the enhanced aridity during marine isotope stage 22 that caused the spread of savanna and arid zones across much of continental Africa pushed early Homo populations in Africa to adapt or migrate to avoid extinction,” they write in their paper. “Rapid migration in response to a severe climate trigger and concomitant means to escape is what can account for the … migration out-of-Africa at 0.9 million years ago and contribute to the modern genomic evidence in modern African populations of the bottleneck.”
The findings have been published in the Proceedings of the National Academy of Sciences.
Comment: I have found this stuff fascinating as far back as when I watched the National Geographic specials with Louis B. Leakey digging for bones in Olduvai Gorge. I started at RPI majoring in geology figuring that would be a good way to get into paleontology. Only later did I transfer to anthropology… and ROTC.
This story is a good example of what effect a changing climate can have on humans even when they occur on a geological time scale. Reducing our breeding population to barely 1,300 individuals and causing our ancestors to un-ass the area for parts unknown are damned drastic effects. In this case, humans certainly had no hand in influencing this particular episode of climate change. It would be interesting to compare and contrast the conditions leading to the Mid-Pleistocene Transition to what we’re seeing/not seeing today.
TTG
https://pastglobalchanges.org/publications/pages-magazines/pages-magazine/11517
Fascinating. Thanks for posting!
I agree!
But we won’t have much trouble escaping the current Climate Catastrophe™ given that it isessentially bogus, yet we will have to escape the Carbon Tax and assorted shenanigans. 🙂
900,000 human prototypes were driving too many gas powered cars, running un-carbon taxed factories and mowing their lawns with combustion engine mowers? Who would have guessed? I mean that is the kind of stuff that causes climate change isn’t it? Al Gore, Newsome and friends wouldn’t lie to us. That’s one thing I know for sure!
Another big surprise is that when the climate changes, people adapt and migrate. PhD level discovery right there! That said there was probably a big die-off of prototypical liberals, who seem to be the ones who think they will just sit there watching the water levels rise, over decades, from melting ice up north until it’s up to their knees, then their chins and then….well….bubbles where the liberal was standing. How high is the water momma? It doesn’t matter son. Were doomed, DOOMED!
You need to read again, it was not 900,000 humans.it was 900,000 years ago and 1,300 humans.
are you sure it wasn’t 900, 231.17 years and 1,276 human prototypes?
It’s a camp fire story, ok? Don’t take it so seriously. In ten years it will be a totally different story.
The data are pretty compelling. The details may change somewhat, but the overall outline is convincing.
That said, it’s science, and that means that it’s also a work in progress. I guess we’ll have to wait and see.
Eric doesnt tend to let the facts get in the way of his opinions. He has his opinions and that is that. He just likes to argue sometimes. The whole zero sum Middle Eastern mindset.
Stefan,
I work with big data and complex systems. I understand that it is near impossible to develop a complete and accurate understanding from a few data points. Under such circumstances, if you get it right it’s more by lucky guess than anything else. With scenarios that may have occurred 900,000 years ago it is even more challenging b/c you cannot test the predictive power of your model, nor adjust and refine the model when it misses the mark.
But you and your jihadi pals should be busy plotting the assassination of these infidel scientists. They’re worse than Salman Rushdie in going against the truth of Allah.
Maybe Academia studies thousands of years from now will reveal that mass migration from the southern US border current day was largely in part due to skewing the US census to capture all the political power and to bludgeoning to death the middle class voting power.
This is after all the dinosaur co2 emissions ended the ice age? We should thank all those ‘mericans who shot all those buffalo. If not for them global warming would have sunk John Kerry before he became a private jet flying climate change savior.
TTG
“Reducing our breeding population to barely 1,300 individuals”
I think that is a mis-statement of the findings. It is not that there were only 1300 individuals. The DNA indicates that a particular group that we descended from was only 1300 individuals at that time. There were likely lots of other people around experiencing various levels of success or failure. But, for whatever reason, they did not participate in the particular history (migration?) that led the descendants of that group to long term success. The rest were not necessarily wiped out, but more likely lost out in later competition with the descendants of that group. Given the time frame (900000 years ago) it seems that Neanderthals and Denisovans were also descendants of that group. They are gone much more recently, and we don’t know why. We are finding DNA traces of them now (very recently) that we know how to look. Even much more recent European hunter-gatherers (dark skin with blond hair) are rapidly approaching undetectabilty in the gene pool. The descendants of all those other people from 900000 years ago have had a lot longer process of dilution if they survived but lost out in subsequent competition.
So my take is that the story is a lot less dramatic than it sounds.
fredw,
I think there was a second wave of migrations out of Africa. That second wave outlasted the Neanderthals and Denisovians and probably others who descended from the first migration out of Africa. At least that’s the current understanding, until new information is discovered. In my opinion, it’s still a dramatic story.
TTG
Some related data in a different context. Some initial DNA studies on dogs concluded that pre-Columbian dog breeds were completely wiped out by European breeds after 1500. Still not clear why, but suspicion falls on the same disease susceptibilty that devestated the humans. But, as always, it is more complicated than that. And the interesting part of getting off the track of human development is that the data is MUCH more recent. And the specifics of dilution are MUCH more visible. My expectation is that human intermixing 850000 years ago would have operated similarly.
If this interests you, here is an exposition of the “wiped out” scenario:
https://www.smithsonianmag.com/smart-news/how-european-dogs-devastated-indigenous-american-pup-populations-180969561/
And here are a couple of deeper dives:
https://www.science.org/doi/10.1126/science.aao4776
https://royalsocietypublishing.org/doi/10.1098/rspb.2013.1142
“The Conquistadores used perro de guerra (war dogs) extensively in the Americas. They proved to be dreadfully effective weapons against Aztec and Inca troops. The Aztecs had only ever seen little Chihuahuas that they used primarily used for food.
By contrast, the Spanish had huge mastiffs, molossus dogs, deer hounds, and greyhounds. Many of these dogs were absolute behemoths – up to 250 pounds and three foot high at the shoulder. They were bred for war, and often wore armor with spikes and even spiked collars, and were more than capable of disemboweling an enemy with fangs alone.” JFF
https://markamorin.com/2021/01/15/perro-de-guerra-conquistador-war-dogs/
“The Conquistadores used perro de guerra (war dogs) extensively in the Americas. They proved to be dreadfully effective weapons against Aztec and Inca troops. ”
Spreading the religion of Christ to the natives using war dogs. Gotta love it. Convert or die, to hell or Connaught. Amazing how things can be so wonderful and beautiful, in this case Christianity, and responsible for so much suffering at the same time.
fredw,
Thanks for the info. DNA analysis has been a boon to furthering our knowledge of early development of humans, dogs and other creatures. Even our understanding of more recent history has benefitted.
As a completely random aside, my family has kept pet rabbits for the last 30 years. Only recently, I learned that our domesticated rabbits all came from European stock. They cannot interbreed with our North American rabbits.
FredW –
I used to have a yellow Carolina Dog. That line is said to be pre-Columbian. Then there are Malamutes, Huskies, Chihuahuas etc. I’m sure many dogs in the pre-contact Western Hemisphere were wiped out. But surely not all.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3730590/
leith
You are correct about Carolina dogs. Since the time of the original studies, biologists have looked more carefully at more breeds. Carolina dogs are one of several breeds found to exhibit pre-Columbian DNA characteristics. Also Chihuahuas and a couple of South American breeds that I have never otherwise heard of. (Chihuahuas preferably with the Les Nesman pronunciation.) And of course there is no absolute dividing line. The original, absolute claim does not hold up under detailed analysis. The prevalence of European mitochondrial DNA is very striking, but not (yet?) total.
Part of my point was that even a small projected mitochondrial or Y-chromosome pool does not mean that the rest of the gene pool is similarly narrow. Which is to say that those 1300 are not necessarily all of our ancestors from that time. Human (mammal) mixing is widespread and relentless right up to the point where divergence reaches mutual infertility.
leith
Re-reading the “deeper dive” studies referenced above, I have to note that the differences are not as easily noticed as I had thought. Dogs came to the new world relatively recently, so there has been much time for distinctive mutations to occur. The distinction is being made largely based on the proportion of distinctively Asian mitochondrial sequences. So, as compared to the situation 900000 years ago, we have much more knowledge of pre-existing DNA lines. But there is lots of overlap between Asian and European lines, so the distinctions are not absolute. Analysis is often based on proportions rather than distinguishable content.
“there has been much time”
“there has not been much time”
Regardless of climate change humans are on a course of depleting the worlds resources through overpopulation and consumption which will destroy the earth way before the effects of climate change..
“which will destroy the earth…”
Not quite, it will possibly destroy humans and quite a lot of other living matter animal and plant (Sixth Extinction) but The Earth itself is quite impervious to such “minor” contingencies, thank you very much!
you are right I misspoke, the earth will still exist but not in the diverse and beautiful place that it once was.