Why we should be excited by 100,000 year old human teeth from China

by Matthew Cobb

I told you all the other day – discoveries in recent human evolution are appearing at an astonishing pace. I just gave my final lecture of the year to the students on the first year Genes, Evolution and Development course at the University of Manchester; last night, at around 23:30, I had to change the lecture because of a discovery that had just been reported in Nature.

47 teeth, clearly from modern humans, have just been found in a massive cave system in southern China. They are dated to over 80,000 years ago – the date range is 80-120,000 years. There were no tools associated with the find, so the researchers asssume that people were not living in the cave system, but rather these teeth came from bodies that were dragged into the caves by large predators (hyena bones were also found). Here are the teeth – these could have been pulled from your mouth (although they probably show less decay than would be in your teeth – much less than in mine!).

Photo: S. Xing and X-J. Wu (Nature).

Why is this a big deal? Because we weren’t supposed to be there at that time. Although there was archaeological evidence of humans having left Africa at around this time – there are traces of 100,000 year old human settlements in Israel – it had been argued that the expansion never got any further, and that the key wave of migration took place around 50-60,000 years ago.

These 47 teeth show that humans successfully left Africa and colonised an important part of the planet, tens of thousands of years earlier than we thought.

This figure from Liu et al (2015) shows the location of the material in the cave system:

a, Location of the Daoxian site. Late Middle Pleistocene and Late Pleistocene localities with human remains that have been included in the morphological and/or metric comparison with Daoxian are also marked on the map. 2: Tianyuan Cave; 3: Huanglong Cave; 4: Liujiang; 5: Zhiren Cave; 6: Tubo; 7: Xujiayao; 8: Luna; 9: Chuandong; 10: Malu Cave; 11: Lijiang; 12: Longlin; 13: Huli Cave; and 14: Xintai. The map is adapted from the original Chinese map from National Administration of Surveying, Mapping and Geoinformation of China (http://219.238.166.215/mcp/index.asp). b, General view of the interior of the cave and the spatial relationship of regions IIA, IIB and IIC, with some of the layers marked. c, Plan view of the excavation area. d, Detail of the stratigraphic layers of region II of the Daoxian site. All human fossils come from layer 2.

The key question now is what happened to that first wave of migration – did they die out, or did they meet up with subsequent migrants and exchange their genes? For the moment, there is no DNA to be analysed from these teeth. Furthermore, if people went to China, why didn’t they also spread up into Europe at this earlier date? We are confident this is not the case, because all the archaeological evidence argues against it.

Maybe Western Eurasia was too full of Neanderthals at the time, and it was only later, around 50,000 years ago that it was ecologically possible for hunter-gatherers to spread northwards – this would suggest that when we did successfully colonise Western Eurasia, either the Neanderthal population had already diminished for unknown reasons, or we had decisive cultural advantages that enabled us to rapidly spread into their areas.

As I said in a previous post, if I had my time over again, this is the area of science I would study. It is simply amazing.

This infographic from Nature sums up the new way of thinking:

 

References:

Callaway (2015) ‘Teeth from China revea early human trek out of Africa’. Nature website

Liu, W. et al. ‘The earliest unequivocal modern humans in Southern China’ Nature http://dx.doi.org/10.1038/nature15696 (2015).

58 Comments

  1. Merilee
    Posted October 15, 2015 at 7:37 am | Permalink

    Very cool!!

  2. GBJames
    Posted October 15, 2015 at 7:44 am | Permalink

    sub

  3. Randy Schenck
    Posted October 15, 2015 at 7:53 am | Permalink

    Dig further must be the calling.

  4. Vaal
    Posted October 15, 2015 at 8:10 am | Permalink

    Fascinating, thanks.

    Reminds me, I have to see the dentist.

    • Filippo
      Posted October 15, 2015 at 10:42 am | Permalink

      I got prepped for a crown yesterday.

      I wonder where anesthesia lies on the totem pole of important scientific discoveries.

      (And human primates gripe about “having” to go to the dentist.)

      • Marella
        Posted October 16, 2015 at 7:41 pm | Permalink

        Anaesthesia is right up the top of the totem-pole, without it there would be no surgery worth the name. No heart transplants, no nose jobs, no nothing, except desperate amputations of gangrenous limbs done by men who measured their success by their speed.

      • rickflick
        Posted October 16, 2015 at 9:06 pm | Permalink

        I like to thank my physician and dentist each time I visit them. They are widely appreciated by society, but I still want to make a point of being very thankful. Without them I would probably been dead several times by now and have suffered greatly more than I actually have. Oh, I thank anesthetics too, of course.

  5. rickflick
    Posted October 15, 2015 at 8:11 am | Permalink

    These teeth look to be in perfect condition. I find that amazing. Morphology alone can tell us if these are definitely our species, but enamel is very friendly to genetics. I have to believe there will be no difficulty getting good DNA evidence from them. The cave, if not cold, at least should have held a relatively cool stable temperature, keeping the DNA intact. I hope there will be a follow-up on the DNA soon. It would be fascinating if there was a small fraction of Neanderthal genes.

    • Anonymous
      Posted October 15, 2015 at 8:39 am | Permalink

      Yes, these teeth look good. I’m a dentist, and teeth do hold up well over time. Some of these are very eroded and worn, but others look to have pristine grooves and cusps. Those in good condition likely belonged to an adolescent or young adult. No sugar and no processed food, so no signs of decay. The fractures present were probably from occlusal trauma.
      Great stuff.

      • rickflick
        Posted October 15, 2015 at 9:01 am | Permalink

        Great stuff indeed. Thanks for the added detail.

      • Tom Snow
        Posted October 15, 2015 at 12:16 pm | Permalink

        I was just about to mention that myself. Not long ago some skeletons were unearthed from the ruins of Pompeii, with similarly undecayed teeth; the author of the article pointed out it was because they didn’t eat all the sugar that we do.

  6. Jeffrey Jones
    Posted October 15, 2015 at 8:19 am | Permalink

    If they had found 100 000 year dentures that would really have been something.

    • rickflick
      Posted October 15, 2015 at 8:50 am | Permalink

      100 000 year old dentures would indeed be remarkable. But, I find it quite interesting that the Pre-Columbians of Central America are known to have performed tooth implants using antler material.
      The condition of the new find makes me think they may not have needed dentures. I would guess that their diet would have helped prevent decay, while ours promotes it.

      • Kevin
        Posted October 15, 2015 at 10:04 am | Permalink

        Some of teeth health is genetics. My wife has almost no cavities, and I have about 25. One of my kids has already 4 but the other one has 0. They eat the same sugary American foods and brush exactly the same amount.

        I also think exercise helps, that is, higher metabolism can be better and I am certain my ancestors 100k years ago were lean fighting machines.

        • darrelle
          Posted October 15, 2015 at 10:53 am | Permalink

          I agree. My teeth care habits are no better than average I am sure, and I’ve never had a cavity. But I know plenty of people with habits at least as good as mine that have many.

          I’ve never had any dental procedure besides cleaning.

          • rickflick
            Posted October 15, 2015 at 11:02 am | Permalink

            “I’ve never had any dental procedure besides cleaning.”

            Lucky you. You could sell your genes on e-bay.

        • DiscoveredJoys
          Posted October 15, 2015 at 11:28 am | Permalink

          Me and Mrs Discovered Joys have lots of fillings and crowns (British dentistry of a certain era) but our two children, now in their 30s have one minor filling between them (I don’t know how they share it around).

          Perhaps it was because we gave them fluoride tablets (gasp! horror!) when they were young.

          • Diane G.
            Posted October 16, 2015 at 3:03 am | Permalink

            Pretty similar here, except my kids–24 & 30–have NO cavities. I attribute it to the fluoride, too, including the little pills of it I was given to take during pregnancy since we’re on well water.

            OTOH, many of their peers have had significant numbers of cavities; I suspect our luck is also due to having very little in the way of soft drinks at home and to not constantly feeding them.

          • rickflick
            Posted October 16, 2015 at 6:46 am | Permalink

            We have a similar situation. Mr. and Mrs. rickflick: lots. Offspring: very few, with fluoride treatments.

        • Posted October 15, 2015 at 10:58 pm | Permalink

          How do you separate genetics from early colonization by varying strains of oral flora? Maybe one of your kids’ mouths was colonized by your bacteria and the other by your wife’s? Or something…

        • rickflick
          Posted October 16, 2015 at 6:40 am | Permalink

          I suspect there are significant genetic/racial differences as well. I met a fellow from Kenya who said he had never had a cavity and saw non in his African friends. He claimed all the dentists in Kenya were for the Europeans living there. Here is an interesting map. It looks like China has few problems while Canada does poorly:

          http://www.freysmiles.com/blog/view/what-countries-have-the-lowest-prevalence-of-cavities

          • rickflick
            Posted October 16, 2015 at 6:52 am | Permalink

            The link above makes the point that it is believed the prevalence of refined sugar is the culprit:
            “2003 WHO oral health report:
            Currently, the disease level is high in the Americas but relatively low in Africa. In light of changing living conditions, however, it is expected that the incidence of dental caries will increase in many developing countries in Africa, particularly as a result of a growing consumption of sugars and inadequate exposure to fluorides.”
            My friend from Kenya claimed he ate a lot of raw sugar cane as a child, which suggests that there is something about refinement that is a factor.

    • Posted October 15, 2015 at 9:18 am | Permalink

      Please! Erich von Däniken is still giving lectures and needs no encouragement!

  7. Jeffery
    Posted October 15, 2015 at 8:20 am | Permalink

    I got into the comments on a Yahoo! article on this yesterday; the creatards had already shown up, with one asking, “Where’s all of the hundreds and thousands of skeletons showing gradual changes in human beings?” I replied with an explanation as to the infrequency of remains being fossilized (the smaller the population of a given ancient species, the fewer fossils you’re going to find, as well)- then I told him not to bother with the, “Where’s all the transitional fossils?” argument as it’s been thoroughly answered by examples from other kinds of animals (so thoroughly that you almost never hear it brought up anymore) and, that if he actually knew how to THINK, he could extrapolate from that.

    • eric
      Posted October 15, 2015 at 8:33 am | Permalink

      I get both baffled and amused every time I hear about someone arguing that 50,00-100,000 year old remains that are identifiably homo sapiens supports a 10,000 year old earth over evolution.

    • Mark Sturtevant
      Posted October 15, 2015 at 9:08 am | Permalink

      There are fossils that show gradual, slow change in the lineage leading to our species. Here is a graph that indexes the ratio of predicted brain size (from cranium size) to body size over time. It shows a range of brain sizes at a given time (like today), plus a definite steady increase. It is an old figure, but I bet it still holds up.

  8. Posted October 15, 2015 at 8:39 am | Permalink

    What I love, absolutely love, about these announcements (these teeth, water on Mars, the Homo naledi discovery in S. Africa), is the sure and certain knowledge that even more wonderful announcements of marvelous discoveries are in the pipeline just awaiting their proper validation process to be completed before bursting on the world.

    • rickflick
      Posted October 15, 2015 at 9:06 am | Permalink

      That suggests the question – is the rate of discovery in human ancestry really increasing? If so, why? Are there now more resources going into this research? It is certainly a welcome development for us curious readers.

      • darrelle
        Posted October 15, 2015 at 9:55 am | Permalink

        There may of course be several reasons but I think the two most likely culprits are, 1) the knowledge / experience / skill base in the relevant disciplines has reached a tipping point and, 2) advances in the technology of the tools used in the relevant disciplines.

        The knowledge, skill and tech has reached the point where extracting useful and reliable data from even small badly degraded samples is routine, or nearly so. This in turn is quickly increasing the range and amount of data available, which synergistically pumps up the knowledge, skill and tech base even more.

        • rickflick
          Posted October 15, 2015 at 10:38 am | Permalink

          It occurs to me, along these lines, that analysis of teeth from museums discovered long before DNA analysis was available has probably been done on a wide scale already. This should certainly solidify our understanding of the hominin evolutionary tree.
          As far as discoveries in China, I recall a recent news item that they are increasing funding for research in all areas of science. That should lead to even more new finds.
          Maybe this is the golden age of paleoanthropology?

          • darrelle
            Posted October 15, 2015 at 12:06 pm | Permalink

            It sure seems to be heading that way. (golden age that is)

            • Jeffery
              Posted October 15, 2015 at 7:01 pm | Permalink

              One factor being forgotten here is the simple fact of the world’s growing population: more people= more scientists. Unfortunately, it also means many more idiots, as well…..

        • Posted October 15, 2015 at 11:50 am | Permalink

          I’d add a version of 1): new areas are now being explored because of a critical mass of researchers. I don’t find it at all surprising in a way that China is home to many fossils and other ancient finds like this: Large area, but relatively unexplored because of economic/political etc. factors.

          (I don’t of course mean that this specific find isn’t surprising.)

          • darrelle
            Posted October 15, 2015 at 12:15 pm | Permalink

            Good point.

            Regarding China, I wonder if large areas with climates favorable for preservation of remains might also be contributing to the wealth of discoveries being made there.

  9. Martin Breslow
    Posted October 15, 2015 at 9:21 am | Permalink

    How many Neanderthals and Homo Sapiens do we think existed back then?

    • Torbjörn Larsson
      Posted October 15, 2015 at 10:38 am | Permalink

      A very good question! The putative migration time would be coincident with a peak in the 2011 population estimate of at least 16.1 kindividuals. [ https://whyevolutionistrue.wordpress.com/2011/09/18/how-big-was-the-human-population-bottleneck-not-anything-close-to-2/ ]

      As I remember the figures at the time, the rest of humans such as Neanderthals and Denisovans each numbered some 2-6 kindividuals.

      Compared to our closest extant relatives that is pitiful unless I am mistaken, I think estimates on chimp and bonobo bottlenecks are at least 10 times as large.

      If someone has more recent data – or any references since I can’t access the full set today – it would be welcome!

  10. Mark Sturtevant
    Posted October 15, 2015 at 9:23 am | Permalink

    I will try to find time to look into this. My questions are how sure they are that these are H. sapiens? Could the teeth belong to advanced H. erectus (“Peking man”? Also, how sure are they about the age? It is well known that cave material, though often well preserved, is notoriously hard to date accurately.

    • Dave H
      Posted October 15, 2015 at 9:44 am | Permalink

      According to the experts I’ve seen quoted on this, the teeth are unequivocally modern. I’m not personally qualified to judge, but if the likes of Chris Stringer (NHM, London) are satisfied with the ID, then that should be good enough.

      Reading the paper, the teeth were found encased in a calcite layer underneath a stalagmite deposit that could be radiometrically dated, and in association with animal species characteristic of that part of the Pleistocene. The dating evidence therefore also appears to be sound.

    • TJR
      Posted October 15, 2015 at 10:15 am | Permalink

      That was my first thought, too, but the linked article says

      “Their small size, thin roots and flat crowns are typical for anatomically modern humans — H. sapiens — and the overall shape of the teeth is barely distinguishable from those of both ancient and present-day humans.”

      Let’s hope there’s some DNA evidence coming soon……

  11. boggy
    Posted October 15, 2015 at 9:39 am | Permalink

    It may be possible to extract DNA from the pulps (‘nerve’) of the teeth, and other info can be gained from calculus deposits. No doubt the archaeologists are aware of this.

  12. rickflick
    Posted October 15, 2015 at 9:59 am | Permalink

    In the case of H. Naledi, probably a much older sample, inspection of the calculus showed evidence of (if I remember right) a grain diet. Apparently, microscopic particles survive to tell the tail.

    • rickflick
      Posted October 15, 2015 at 9:59 am | Permalink

      tale?

  13. Torbjörn Larsson
    Posted October 15, 2015 at 10:22 am | Permalink

    Thanks for more details on this! The press release merited a huge “huh!?” on my early-morning-with-not-enough-coffee-yet scale. I have slowly come to the conclusion it was real press release. =D

    Preliminary thoughts is that it makes you wonder what took the ancestors of Australians so long.

  14. Posted October 15, 2015 at 10:24 am | Permalink

    “Maybe Western Eurasia was too full of Neanderthals at the time…”

    Still is. Ever hear of Putin?

    • Torbjörn Larsson
      Posted October 15, 2015 at 10:50 am | Permalink

      That’s pretty racist of you, even if it is only bigoted about some of our genes by now. Neanderthals was – still partly is – us.

      John Hawks (of H. denali fame) would have a good time adding it to his “Neandertal anti-defamation files”! [ http://johnhawks.net/tag/Neandertal%20anti-defamation%20files.html ; http://www.nytimes.com/2013/05/03/opinion/global/Who-Are-You-Calling-a-Neanderthal.html ; https://whyevolutionistrue.wordpress.com/2015/10/13/neanderthal-genes-are-everywhere/ ]

    • Grania Devine
      Posted October 15, 2015 at 11:40 am | Permalink

      Very unkind to Neanderthals!

      • Filippo
        Posted October 15, 2015 at 1:24 pm | Permalink

        How does Putin compare to certain members of the U.S. Congress?

    • W.Benson
      Posted October 15, 2015 at 12:31 pm | Permalink

      I don’t hate Putin. What is wrong with me?

    • Posted October 15, 2015 at 3:15 pm | Permalink

      Calm down on the social justice warrior stuff. I was making a joke using one of the definitions of Neanderthal (an unenlightened or ignorant person; barbarian). It was not meant as a blanket insult to a group of extinct hominins.

      Go stuff yourself for calling me a racist, you asshole.

      • Posted October 15, 2015 at 5:12 pm | Permalink

        Both of you guys knock of the name-calling, which is a Roolz violation, and apologize. And if someone calls you a name, you’re not entitled on this site to call them a name back. I INSIST on civility.

        • Posted October 15, 2015 at 6:23 pm | Permalink

          Apologies to the host and to Torbjörn. I stepped out of line.

    • Diane G.
      Posted October 16, 2015 at 3:12 am | Permalink

      I was going to give you a hard time about calling Putin’s territory part of “Western” Eurasia (which I took to mean geographicly, not culturally). But I think you’ve already been through enough…

      😀

      • Posted October 16, 2015 at 8:57 am | Permalink

        Thanks for the comment. Let’s just add more pointless pedantry onto what was just a light attempt at humor. Well done : )!

  15. Posted October 15, 2015 at 1:09 pm | Permalink

    The time between 6000 bce and 80,000 bce was how long it took early man to fund dentist. Did they mention if the found any really early National Graphics or plastic chairs?

  16. Mark R.
    Posted October 15, 2015 at 1:17 pm | Permalink

    Thanks for this interesting post. How long does it take to analyze DNA? Inquiring minds want to know.

    What would be incredible is if some of the DNA matches up with modern Chinese people…or perhaps an altogether different population. It will also be interesting if Neanderthal DNA is found.

    • Posted October 15, 2015 at 2:13 pm | Permalink

      The chat on twitter last night was that these samples were too old and not cold enough to give decent DNA samples. These teeth are around twice as old as the Denisovan and Neanderthal samples, and they were not found in a cave at high latitudes. It may simply not be possible to get decent DNA out of them. It could all have been eaten by bacteria, as seems to have been the case with the Homo floresiensis DNA.

      • Mark R.
        Posted October 15, 2015 at 2:26 pm | Permalink

        Thanks for the clarification…that’s a bummer that the DNA isn’t viable.

  17. Diane G.
    Posted October 16, 2015 at 3:13 am | Permalink

    This is just so much…fun! Go, science!


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