7 ms·

Fossils from Morocco complicate the story of modern humans

192 points by biridir 9y ago

atroll 9y ago
damn it morocco
meri_dian 9y ago
The San people of southern Africa are claimed to be the living human group with the most ancient divergence from the rest of humanity, around 200,000 years ago. That they are so similar to the rest of humanity has always made me wonder if the commonly accepted divergence date ranges should be pushed back. From the Wiki: "A DNA study of fully sequenced genomes, published in September 2016, showed that the ancestors of today's San hunter-gatherers began to diverge from other human populations in Africa about 200,000 years ago and were fully isolated by 100,000 years ago, well before the first archaeological evidence of modern behaviour in humans." https://en.wikipedia.org/wiki/San_people?wprov=sfla1 https://en.wikipedia.org/wiki/San_people?wprov=sfla1
- Danihan 9y ago
  Do you know if they are related to the Berbers?
  - hasenj 9y ago
    Seems rather unlikely, given their appearance.
  - micheljones 9y ago
    Well, we are all related to each other, the only question is how _closely_ related we are. And as for that, any non-Khoisan/non-Pygmy human subgroup is more closely related to any other non-Khoisan/non-Pygmy subgroup than they are to Khoisan or Pygmy people. In other words, Khoisan and Pygmyies are the most distant cousins to all other homo sapiens (diverged from us 175-200 thousand years ago).
- tim333 9y ago
  I guess evolutionary change is gradual so it's hard to have a cut off date for when pre homo sapien ancestors had kids that counted as homo sapiens. The origins of cooking going back 1.9 million years implies the ancestors must have been a bit human like. https://www.theguardian.com/science/2011/aug/22/cooking-origins-homo-erectus https://www.theguardian.com/science/2011/aug/22/cooking-orig...
  - sulam 9y ago
    Evolution is not single speed. For a relatively static population with no need to change their lifestyle it will run more slowly. For a dynamic population with bottlenecks it can run very quickly.
- micheljones 9y ago
  Not only that, their divergence date (cca 175kya-200kya), combined with the fact that they have language, culture and art disproves the 'behavioral modernity' theory which posits that human brains evolved to use language and produce culture and art relatively recently (30kya) based on the oldest currently available archeological finds of expressions of culture/art.
andrewflnr 9y ago
I wish they'd go into more detail about how the shape of the brain case affects brain organization. Does anyone have a good layman-oriented source on that? Edit: it looks like both are affected by differences in brain development. https://www.mpg.de/623578/pressRelease201011021 https://www.mpg.de/623578/pressRelease201011021
stefantalpalaru 9y ago
Time to revisit this theory: https://en.wikipedia.org/wiki/Multiregional_origin_of_modern_humans https://en.wikipedia.org/wiki/Multiregional_origin_of_modern...
eponeponepon 9y ago
I've never really grasped where the surprise comes from with these kinds of discoveries - we know that our ancestry always had the potential to give rise to lines that look very much like us, since we look very much like us. Why should it be a surprise if it happened more than once? We're looking at a terribly long timescale, after all - at least by comparison to our recorded history.
- gus_massa 9y ago
  Evolution is not linear. At each step there are multiple choices. If you split a population, each one will have different problems in it's environment to solve or they may "find" different solutions to the same problems. After some time the changes in the ADN make the two population incompatible for reproduction, so they become different species. [An easy case is when the number of chromosomes changes in one of the part but it doesn't change in the others. But more subtle changes are more frequent.]
  - danans 9y ago
    > After some time the changes in the ADN make the two population incompatible for reproduction, so they become different species. The time scales being discussed here are orders of magnitude too short to even consider speciation, evidenced by what we know about our human/Neanderthal hybrid ancestors, and the fact that a Pygmy or Khoi-San person can have viable offspring with any person of the opposite gender in the human diaspora today.
- has2k1 9y ago
  I think how you attribute the surprise matters. The order of discoveries brought forth a conventional story that stood for a seemingly long time. Now that story may need to be re-examined. There is a difference between the discovery & subsequent scientific reports and the story drawn from them. The story is less accurate, tends to be more romantic and gets the widest exposure. Even the scientists subscribe to one version or another because they are human. The likely change in the common story is the source of the surprise and excitement. This process guarantees that there will always be a surprise, and roughly speaking it will be directly proportional to how long the story has been in place and inversely proportional to the number of such competing stories.
tombh 9y ago
Coincidently I've been reading and youtubing about human evolution recently. If anyone's interested here are some bullet point facts that may surprise other laymen. * In the last few years the Out Of Africa theory (modern humans originated solely in Africa) has received stiff competition from the Multi Regional theory. Namely that waves of human species have left Africa since we diverged from chimpanzees 4 million years ago and that our ancestors are from all the homo-inhabited regions of the world to a greater or lesser extent. * Neanderthals and Denisovans are 2 known species that certainly inhabited much of the world (apart from the Americas) from around 2/300,000 to 50,000 years ago. * We certainly bred with Neanderthals and Denisovans, some of us contain up to 4% of their DNA. * Mammals generally take about 5 million years before they evolve far enough to be reproductively isolated. Of course before then there can still be breeding problems, for which there is evidence of in our breeding with the aforementioned. * DNA from human skeletons several hunreds of thousands of years old can still be analysed. * Mitochondrial DNA is passed by mothers only and so undergoes very little mutation. So it provides a stable and valuable signature for detecting ancient affinities between species/sub-species. * By analysing the variation within genes certain characteristics can be interpreted like population size (eg; there were very few Denisovans) and that there are as yet unidentified species that humans have inherited from. * Neanderthals possessed the FOXP2 gene known to be central in human speech. * One of the oldest known oral traditions has evidence to verify a story from around 30,000 years ago: that Australian aboriginees brought the palm tree seeds with them from the north. See: http://www.abc.net.au/news/2015-04-03/aboriginal-legend-palm-tree-origin-central-australia-research/6369832 http://www.abc.net.au/news/2015-04-03/aboriginal-legend-palm... Forgive any errors in this amateur homework report.
- detritus 9y ago
  Wow. That last bullet point is particularly remarkable to me - both the implied level of 'technological understanding' and presumed foreplanning for significant journeys 30K years back and for the capacity of oral history to record what come today might not be the most pertinent information. Also quite amusing in the context of contemporary Australia's philosophy where alien plants and animals are concerned! :)
  - 9y ago
halflings 9y ago
It doesn't seem like there's anything new in this article compared to the original announcement.
micheljones 9y ago
I was always surprised by the tendency of anthropologists to assign hard evolutionary 'milepoints' based on the very limited set of archeological data. Most egregious example is 'behavioral modernity' theory which claims that homo sapiens developed language, culture and art only relatively recently (30kya) because that's how old the currently oldest archeological finds of culture/art expression are. This doesn't stand up even to the simplest application of Occam's razor.
- ralfd 9y ago
  But then the question is why our ancestors didn't invent stuff 100 thousand years earlier.
  - micheljones 9y ago
    Well, that's not what I'm arguing. What I am arguing is that lack of proof is not proof of lack - the fact that, for example, currently oldest artwork we know of is 30 000 years old does not prove that's when homo sapiens started making art and not any earlier, but instead that it proves that humans have been making art AT LEAST 30kya, AND that they must have started doing it earlier. P.S. the 'oldest art is 30 thousand years old' bit is in the context of 'behavioral modernity' theory at the time it was posited, based on European cave art; in the meantime, we've found even older art in a cave in Indonesia (40 thousand years old).
eXpl0it3r 9y ago
I'm surprised how much variations there are in the dating of the fossils. At first it's 40'000 years, then 160'000, then between 280'000 and 350'000. Can someone explain to me why there's so much difference?
- tinix 9y ago
  Carbon dating is a flawed concept.
  - Strilanc 9y ago
    They're obviously not using carbon dating. The ages are too big. IIRC The half life of carbon 14 is too short to distinguish samples that have been decaying for 50k years from background noise. You have to use other kinds of radiometric dating instead.

192 points by biridir 9y ago

damn it morocco

The San people of southern Africa are claimed to be the living human group with the most ancient divergence from the rest of humanity, around 200,000 years ago. That they are so similar to the rest of humanity has always made me wonder if the commonly accepted divergence date ranges should be pushed back. From the Wiki: "A DNA study of fully sequenced genomes, published in September 2016, showed that the ancestors of today's San hunter-gatherers began to diverge from other human populations in Africa about 200,000 years ago and were fully isolated by 100,000 years ago, well before the first archaeological evidence of modern behaviour in humans." https://en.wikipedia.org/wiki/San_people?wprov=sfla1 https://en.wikipedia.org/wiki/San_people?wprov=sfla1

Danihan 9y ago
Do you know if they are related to the Berbers?
- hasenj 9y ago
  Seems rather unlikely, given their appearance.
- micheljones 9y ago
  Well, we are all related to each other, the only question is how _closely_ related we are. And as for that, any non-Khoisan/non-Pygmy human subgroup is more closely related to any other non-Khoisan/non-Pygmy subgroup than they are to Khoisan or Pygmy people. In other words, Khoisan and Pygmyies are the most distant cousins to all other homo sapiens (diverged from us 175-200 thousand years ago).
tim333 9y ago
I guess evolutionary change is gradual so it's hard to have a cut off date for when pre homo sapien ancestors had kids that counted as homo sapiens. The origins of cooking going back 1.9 million years implies the ancestors must have been a bit human like. https://www.theguardian.com/science/2011/aug/22/cooking-origins-homo-erectus https://www.theguardian.com/science/2011/aug/22/cooking-orig...
- sulam 9y ago
  Evolution is not single speed. For a relatively static population with no need to change their lifestyle it will run more slowly. For a dynamic population with bottlenecks it can run very quickly.
micheljones 9y ago
Not only that, their divergence date (cca 175kya-200kya), combined with the fact that they have language, culture and art disproves the 'behavioral modernity' theory which posits that human brains evolved to use language and produce culture and art relatively recently (30kya) based on the oldest currently available archeological finds of expressions of culture/art.

andrewflnr 9y ago

I wish they'd go into more detail about how the shape of the brain case affects brain organization. Does anyone have a good layman-oriented source on that? Edit: it looks like both are affected by differences in brain development. https://www.mpg.de/623578/pressRelease201011021 https://www.mpg.de/623578/pressRelease201011021

stefantalpalaru 9y ago

Time to revisit this theory: https://en.wikipedia.org/wiki/Multiregional_origin_of_modern_humans https://en.wikipedia.org/wiki/Multiregional_origin_of_modern...

eponeponepon 9y ago

I've never really grasped where the surprise comes from with these kinds of discoveries - we know that our ancestry always had the potential to give rise to lines that look very much like us, since we look very much like us. Why should it be a surprise if it happened more than once? We're looking at a terribly long timescale, after all - at least by comparison to our recorded history.

gus_massa 9y ago
Evolution is not linear. At each step there are multiple choices. If you split a population, each one will have different problems in it's environment to solve or they may "find" different solutions to the same problems. After some time the changes in the ADN make the two population incompatible for reproduction, so they become different species. [An easy case is when the number of chromosomes changes in one of the part but it doesn't change in the others. But more subtle changes are more frequent.]
- danans 9y ago
  > After some time the changes in the ADN make the two population incompatible for reproduction, so they become different species. The time scales being discussed here are orders of magnitude too short to even consider speciation, evidenced by what we know about our human/Neanderthal hybrid ancestors, and the fact that a Pygmy or Khoi-San person can have viable offspring with any person of the opposite gender in the human diaspora today.
has2k1 9y ago
I think how you attribute the surprise matters. The order of discoveries brought forth a conventional story that stood for a seemingly long time. Now that story may need to be re-examined. There is a difference between the discovery & subsequent scientific reports and the story drawn from them. The story is less accurate, tends to be more romantic and gets the widest exposure. Even the scientists subscribe to one version or another because they are human. The likely change in the common story is the source of the surprise and excitement. This process guarantees that there will always be a surprise, and roughly speaking it will be directly proportional to how long the story has been in place and inversely proportional to the number of such competing stories.

tombh 9y ago

Coincidently I've been reading and youtubing about human evolution recently. If anyone's interested here are some bullet point facts that may surprise other laymen. * In the last few years the Out Of Africa theory (modern humans originated solely in Africa) has received stiff competition from the Multi Regional theory. Namely that waves of human species have left Africa since we diverged from chimpanzees 4 million years ago and that our ancestors are from all the homo-inhabited regions of the world to a greater or lesser extent. * Neanderthals and Denisovans are 2 known species that certainly inhabited much of the world (apart from the Americas) from around 2/300,000 to 50,000 years ago. * We certainly bred with Neanderthals and Denisovans, some of us contain up to 4% of their DNA. * Mammals generally take about 5 million years before they evolve far enough to be reproductively isolated. Of course before then there can still be breeding problems, for which there is evidence of in our breeding with the aforementioned. * DNA from human skeletons several hunreds of thousands of years old can still be analysed. * Mitochondrial DNA is passed by mothers only and so undergoes very little mutation. So it provides a stable and valuable signature for detecting ancient affinities between species/sub-species. * By analysing the variation within genes certain characteristics can be interpreted like population size (eg; there were very few Denisovans) and that there are as yet unidentified species that humans have inherited from. * Neanderthals possessed the FOXP2 gene known to be central in human speech. * One of the oldest known oral traditions has evidence to verify a story from around 30,000 years ago: that Australian aboriginees brought the palm tree seeds with them from the north. See: http://www.abc.net.au/news/2015-04-03/aboriginal-legend-palm-tree-origin-central-australia-research/6369832 http://www.abc.net.au/news/2015-04-03/aboriginal-legend-palm... Forgive any errors in this amateur homework report.

detritus 9y ago
Wow. That last bullet point is particularly remarkable to me - both the implied level of 'technological understanding' and presumed foreplanning for significant journeys 30K years back and for the capacity of oral history to record what come today might not be the most pertinent information. Also quite amusing in the context of contemporary Australia's philosophy where alien plants and animals are concerned! :)
- 9y ago

halflings 9y ago

It doesn't seem like there's anything new in this article compared to the original announcement.

micheljones 9y ago

I was always surprised by the tendency of anthropologists to assign hard evolutionary 'milepoints' based on the very limited set of archeological data. Most egregious example is 'behavioral modernity' theory which claims that homo sapiens developed language, culture and art only relatively recently (30kya) because that's how old the currently oldest archeological finds of culture/art expression are. This doesn't stand up even to the simplest application of Occam's razor.

ralfd 9y ago
But then the question is why our ancestors didn't invent stuff 100 thousand years earlier.
- micheljones 9y ago
  Well, that's not what I'm arguing. What I am arguing is that lack of proof is not proof of lack - the fact that, for example, currently oldest artwork we know of is 30 000 years old does not prove that's when homo sapiens started making art and not any earlier, but instead that it proves that humans have been making art AT LEAST 30kya, AND that they must have started doing it earlier. P.S. the 'oldest art is 30 thousand years old' bit is in the context of 'behavioral modernity' theory at the time it was posited, based on European cave art; in the meantime, we've found even older art in a cave in Indonesia (40 thousand years old).

eXpl0it3r 9y ago

I'm surprised how much variations there are in the dating of the fossils. At first it's 40'000 years, then 160'000, then between 280'000 and 350'000. Can someone explain to me why there's so much difference?

tinix 9y ago
Carbon dating is a flawed concept.
- Strilanc 9y ago
  They're obviously not using carbon dating. The ages are too big. IIRC The half life of carbon 14 is too short to distinguish samples that have been decaying for 50k years from background noise. You have to use other kinds of radiometric dating instead.