Holy smokes. Human ancestors were literally some Land of the Lost remnant population in a remote valley for 117,000 years. Theories have been proposed that the success of the human expansion out...
Human ancestors in Africa were pushed to the brink of extinction around 900,000 years ago, a study shows. The work, 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
…
“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.”
Holy smokes. Human ancestors were literally some Land of the Lost remnant population in a remote valley for 117,000 years. Theories have been proposed that the success of the human expansion out of Africa 60,000 years ago may have been due to social adaptations and developments that competing hominids didn’t have, like perhaps complex language or political theory.
Having a possible legacy of intensely shared community in our genetic past may be what gave us that edge.
That's a oddly specific number. The Nature article didn't shed light on quite how the number was determined, and the reference article by Hu et al. is paywalled after the summary mentions "a newly...
just 1,280 [breeding individuals]
That's a oddly specific number. The Nature article didn't shed light on quite how the number was determined, and the reference article by Hu et al. is paywalled after the summary mentions "a newly developed coalescent model" (maybe I wouldn't understand Hu's paper anyway.) Can anyone here elucidate?
They've developed some new technique called FitCoal: fast infinitesimal time coalescent process. I don't really understand it, but the claim is that historical population sizes leaves a genetic...
The
bottleneck was estimated to persist for 117 kyr,
from 930 ± 23.52 (SEM) (range, 854 to 1042)
to 813 ± 11.02 (SEM) (range, 772 to 864) kyr BP.
The average effective population size (i.e., the
number of breeding individuals) (26) during
the bottleneck period was determined to be
1280 ± 131 (SEM) (range, 770 to 2030), which
was only 1.3% of its ancestral size (98,130 ±
8720; range, 58,600 to 135,000).
They've developed some new technique called FitCoal: fast infinitesimal
time coalescent process. I don't really understand it, but the claim is that historical population sizes leaves a genetic marker in modern humans:
Population size changes that occurred hun-
dreds of thousands of years ago affected the
rates of coalescence and thus have left their
signatures in the site frequency spectrum (SFS)
of genomic sequences. The SFS is the distri-
bution of allele frequencies in the sequences,
randomly collected from the present-day hu-
man population. Each SFS category contains
a certain number of mutations of the same
size. Because SFS is crucial for demographic
inference (6, 8–12) and construction of key
summary statistics (13), many efforts have been
devoted to deriving its analytical formulas (14–17).
FitCoal is then some complicated numerical technique for analysing this signature
Very cool! Thank you (and I understand it even less than you lol, but neat to know someone has it figured out, and wow what an amazing l-o-n-g t-h-i-n bottleneck for us to have survived though)...
Very cool! Thank you (and I understand it even less than you lol, but neat to know someone has it figured out, and wow what an amazing l-o-n-g t-h-i-n bottleneck for us to have survived though)
"social adaptations ... like ... political theory" .. Now i'm speechless
I'm trying to understand the last paragraph. Even though Ashton seems to be in agreement with the finding on the whole, is he implying that there were ancestors of modern humans, or perhaps...
I'm trying to understand the last paragraph.
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.”
Even though Ashton seems to be in agreement with the finding on the whole, is he implying that there were ancestors of modern humans, or perhaps ancestors of Neanderthals and Denisovans who eventually added to our gene pool, that survived outside of Africa this early? Because the article seems to make it clear that this population was before any of those existed.
There's some discussion in the article: The claim is this bottleneck occurred before the divergence of Neanderthals and Denisovans, and the bottleneck is consistent with sparse archaelogical...
There's some discussion in the article:
The existence of the ancient severe bottle-
neck could explain the extreme scarcity of the
available hominin fossil record in Africa and
Eurasia between 950 and 650 kyr BP (Fig. 5 and
fig. S24). In Africa, only a few fossil specimens
dated in this time period have been found, in-
cluding the cranial fragments from Gombore
in Ethiopia and the fossil samples from Tighenif
in Algeria (36, 37). Although the taxonomic sta-
tuses of these fossils are still not clear, they have
features resembling those of later fossils at-
tributed to Homo heidelbergensis. They are dif-
ferent from the coeval Homo antecessor from a
paleoanthropological site in Spain (Atapuerca,
Gran Dolina), and some scholars considered
H. antecessor as a possible alternative for the last
common ancestor (LCA) (38). During the same
chronological interval, the East Asian fossil
record contains specimens identified as Homo
erectus (39). It does not appear that East Asian
H. erectus is connected to the ancient severe
bottleneck because it is unlikely to have contrib-
uted to the lineage leading to modern humans
(38). In addition, coincident with this bottleneck,
two ancestral chromosomes are believed to have
fused to form chromosome 2 in humans around
900 to 740 kyr BP (40, 41). Therefore, the ancient
severe bottleneck possibly marks a speciation
event leading to the emergence of the LCA
shared by Denisovans, Neanderthals, and mod-
ern humans, whose divergence has been dated
to about 765 to 550 kyr BP (38, 42, 43).
The claim is this bottleneck occurred before the divergence of Neanderthals and Denisovans, and the bottleneck is consistent with sparse archaelogical evixence from the era (930-810 thousand years ago). (not an expert, can't comment on how good these claims are)
So this would confirm @AdiosLunes' guess. The confusion is that the article is specifically referring to modern human's ancestors and Ashton's speculation is about the total picture of hominids....
So this would confirm @AdiosLunes' guess. The confusion is that the article is specifically referring to modern human's ancestors and Ashton's speculation is about the total picture of hominids. The survivors outside of Africa would be a population that would not be represented in our genetics except through common ancestry much further back. Would that be a fair understanding?
To be honest, not sure. (way out of my field!) You'd have to look up the extent of hominids in the time frame involved - I don't have any idea which hominids were in or out of Africa at what times.
To be honest, not sure. (way out of my field!)
You'd have to look up the extent of hominids in the time frame involved - I don't have any idea which hominids were in or out of Africa at what times.
The only interpretation I could come up with was that other species of Homo that aren't our direct ancestors (e.g. subspecies/populations) didn't necessarily suffer the same crash in population...
The only interpretation I could come up with was that other species of Homo that aren't our direct ancestors (e.g. subspecies/populations) didn't necessarily suffer the same crash in population (but later went extinct). Clarity is certainly needed there, because I was also (and still am) confused.
Human Evolutionary Biology in general and findings like this in particular are why I think the answer to the Fermi paradox is clearly the "rare Earth hypothesis" or some subtype of it. There were...
Human Evolutionary Biology in general and findings like this in particular are why I think the answer to the Fermi paradox is clearly the "rare Earth hypothesis" or some subtype of it.
There were so, so many ways for our species to have gone extinct before we reached our current state of technological development. And there's no certainty that we will ever get out of our solar system before something else takes us out. We are pretty smart but evolution did not equip us with the tools we need to think outside of our Monkey Sphere. Or for the long term.
If these findings are right, it would make a lot of sense that we would have developed a lot of instincts that helped us survive that population crash but might be deleterious to us in the long run. Climate change and our response to the COVID-19 pandemic being two good examples from recent events.
Holy smokes. Human ancestors were literally some Land of the Lost remnant population in a remote valley for 117,000 years. Theories have been proposed that the success of the human expansion out of Africa 60,000 years ago may have been due to social adaptations and developments that competing hominids didn’t have, like perhaps complex language or political theory.
Having a possible legacy of intensely shared community in our genetic past may be what gave us that edge.
It does also explain low human genetic variability. We've long known we went through a recent bottleneck, but I'm not sure we knew the scale.
That's a oddly specific number. The Nature article didn't shed light on quite how the number was determined, and the reference article by Hu et al. is paywalled after the summary mentions "a newly developed coalescent model" (maybe I wouldn't understand Hu's paper anyway.) Can anyone here elucidate?
They've developed some new technique called FitCoal: fast infinitesimal
time coalescent process. I don't really understand it, but the claim is that historical population sizes leaves a genetic marker in modern humans:
FitCoal is then some complicated numerical technique for analysing this signature
Very cool! Thank you (and I understand it even less than you lol, but neat to know someone has it figured out, and wow what an amazing l-o-n-g t-h-i-n bottleneck for us to have survived though)
"social adaptations ... like ... political theory" .. Now i'm speechless
I'm trying to understand the last paragraph.
Even though Ashton seems to be in agreement with the finding on the whole, is he implying that there were ancestors of modern humans, or perhaps ancestors of Neanderthals and Denisovans who eventually added to our gene pool, that survived outside of Africa this early? Because the article seems to make it clear that this population was before any of those existed.
There's some discussion in the article:
The claim is this bottleneck occurred before the divergence of Neanderthals and Denisovans, and the bottleneck is consistent with sparse archaelogical evixence from the era (930-810 thousand years ago). (not an expert, can't comment on how good these claims are)
So this would confirm @AdiosLunes' guess. The confusion is that the article is specifically referring to modern human's ancestors and Ashton's speculation is about the total picture of hominids. The survivors outside of Africa would be a population that would not be represented in our genetics except through common ancestry much further back. Would that be a fair understanding?
To be honest, not sure. (way out of my field!)
You'd have to look up the extent of hominids in the time frame involved - I don't have any idea which hominids were in or out of Africa at what times.
The only interpretation I could come up with was that other species of Homo that aren't our direct ancestors (e.g. subspecies/populations) didn't necessarily suffer the same crash in population (but later went extinct). Clarity is certainly needed there, because I was also (and still am) confused.
Human Evolutionary Biology in general and findings like this in particular are why I think the answer to the Fermi paradox is clearly the "rare Earth hypothesis" or some subtype of it.
There were so, so many ways for our species to have gone extinct before we reached our current state of technological development. And there's no certainty that we will ever get out of our solar system before something else takes us out. We are pretty smart but evolution did not equip us with the tools we need to think outside of our Monkey Sphere. Or for the long term.
If these findings are right, it would make a lot of sense that we would have developed a lot of instincts that helped us survive that population crash but might be deleterious to us in the long run. Climate change and our response to the COVID-19 pandemic being two good examples from recent events.