Homo naledi update part 2: A confusing arm

Homo naledi has a strange arm that combines tree-climbing and tool-using traits. What can explain this dilemma when no tools have been found with them?


Homo naledi is the newest member of our genus (Homo) to be discovered. And ironically, it might also be the oldest; although it has yet to be reliably dated. However, one new thing about it is how it’s being researched. Normally all the data is published in one big lump at the end. However, this time researchers are trying to give updates as they go. And I’m trying to do the same thing.

Last week I talked about some new research on their skull. The discoverers revealed it’s unique, but still definitely belongs to our genus. They also announced the discovery of a new juvenile of Homo naledi. Or rather, they recognised that one of the bones they found before is a separate juvenile specimen.

juvenile Homo naledi

DH6, the new juvenile Homo naledi

This week we’re moving down the body a bit and looking at their arm. In keeping with their new research approach, this has already had some data published about it. And now they’re updating it. The resulting information on the arm doesn’t quite seem right. So what’s going on with Homo naledi‘s weird arm?

I feel it in my fingers

When Homo naledi was first discovered it was notable for not being particularly notable. It had many of the features you would expect for an early member of our genus. It was bipedal but had a small brain. Its legs looked quite modern, but its arms didn’t. It all fit in quite nicely, assuming that they really are the early member of the genus they look like. As I mentioned, they haven’t been dated yet.

However, there were a few exceptions to this “expected” trend. One notable one being their hand. The earlier genus, Australopithecus, seems to have been a tree climber. And their arm was well suited for it. For the most part, Homo naledi inherited this ape-like climbing arm. Even the hand seemed well adapted for climbing, featuring long curved fingers great for grasping branches.

But as I said, the hand was weird. Whilst some parts, like the curved fingers, looked old-school other parts seem a lot more modern. The thumb, for example, is thick and strong; a lot like ours. This is a great adaptation for manipulating stuff and using tools. Not so great for climbing, which is weird given how well suited to that the rest of the hand is.

The other “weird” part of the hand is their wrist. I put weird in quotemarks because it isn’t actually that unique. It’s actually quite similar to ours and other later members of Homo. Which isn’t what you’d expect for an early species, adapted for tree climbing.

The hands of Homo naledi.

Homo naledi and the strange shoulder

On the other hand (pun totally intended) the arm is a bit more consistent with both itself and what’s expected of it. This update provides further information on the arm. And it confirms this pattern.

The rest of the arm seems to be fairly well adapted for tree climbing. It’s similar to those earlier Australopiths like Lucy and distinct from later Homo in many key ways. Notably, the shoulder is orientated slightly more upwards than in modern humans. It was thought that this helps hold the arms over the head, good for dangling below trees and swinging from branch to branch. However, new evidence is challenging this view. Nevertheless, it is clearly a common trait in climbing species.

In short, this update reinforces the weird pattern documented during the discovery. A combination of tool-using traits and climbing traits. A few years ago this contradiction would be downright paradoxical. However, recent discoveries are suggesting that tool use evolved earlier than we thought. The Lomekwian is a stone tool industry made by Australopithecus. Perhaps that kicked off hand evolution, which continued with Homo naledi.

first stone tools

The Lomekwian; perhaps the first stone tools. Simple but significant

This does seem to be the best explanation. Whilst the Homo naledi shoulder does point upwards, it’s also angled slightly forwards. The result is that their arm had fairly unrestricted movement around the front of the body. Which is where’ they’d be using tools. A similar pattern is seen in early Homo erectus, and we know they made tools.

Of course, this is all slightly circumstantial. The real clincher would be finding tools associated with the fossils. Which is unlikely, since the site discovered isn’t a habitation site. It’s something far more interesting.

Homo naledi. The palaeoanthropological gift that just keeps on giving. . . mysteries! But I shan’t complain too much. It keeps giving me stuff to write about after all.

References

Feuerriegel, E.M., Green, D.J., Walker, C.S., Schmid, P., Hawks, J., Berger, L.R. and Churchill, S.E., 2017. The upper limb of Homo naledi. Journal of Human Evolution, 104, pp.155-173.

Kivell, T.L., Deane, A.S., Tocheri, M.W., Orr, C.M., Schmid, P., Hawks, J., Berger, L.R. and Churchill, S.E., 2015. The hand of Homo naledi. Nature communications, 6.

Laird, M.F., Schroeder, L., Garvin, H.M., Scott, J.E., Dembo, M., Radovčić, D., Musiba, C.M., Ackermann, R.R., Schmid, P., Hawks, J. and Berger, L.R., 2017. The skull of Homo naledi. Journal of human evolution, 104, pp.100-123.

Marchi, D., Walker, C.S., Wei, P., Holliday, T.W., Churchill, S.E., Berger, L.R. and DeSilva, J.M., 2017. The thigh and leg of Homo naledi. Journal of Human Evolution, 104, pp.174-204.

Williams, S.A., García-Martínez, D., Bastir, M., Meyer, M.R., Nalla, S., Hawks, J., Schmid, P., Churchill, S.E. and Berger, L.R., 2017. The vertebrae and ribs of Homo naledi. Journal of Human Evolution, 104, pp.136-154.

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14 thoughts on “Homo naledi update part 2: A confusing arm”

  1. clayton says:

    I just read an article that said Lee Berger was dating the H.Naledi fossils at between 200,000 and 300,000 yrs old, though he wasn’t saying how he arrived at the dates. Then the gist of the article seemed to be that the Homo Naledi fossils represented a relic species, since they were much more primitive than their contemporary Hominins. The article also pointed out that Flores Man, the Hobbit, who lived much more recently, as you know of course, was a relic population of Homo Hablis, who thus survived quite a long time with the other Hominins. This all tells us (me?) that it’s possible for relic populations to survive long past the times that they are supposed to be extinct. Now, since I am a totally self taught paleoanthro-framma-jamma, without a heavy investment of years of trying to prove one thing or another, I can entertain all kinds of wild theories! The funny thing is, as time goes by and more and more discoveries emerge, the more things seem to confirm those theories. Or, the possibility that those crazy theories could be true.

    1. Adam Benton says:

      Berger’s other big discovery, Australopithecus sediba, also seems to be a relic species. Looks like he might be a man of habit. Alas, until the papers are properly published I can’t really say much more about them.

  2. Mike says:

    Chapter 30 of Berger and Hawks upcoming “Almost Human” says Dinaledi is between 250,000 (date of flowstone) and 450,000 (max according to ESR dating of teeth). I’m sure the “National Geographic” piece Clayton mentions was, in a sense, an accident. They were planning to release the date and the 102 site material and much earlier and thus NG undoubtedly thought that date would be public before the magazine was in the hands of the public. After all, they were going to put the new naledi material on public display on March 18 and that clearly did not happen. “Almost Human” has been repeatedly delayed. I have got to suspect some sort of unexpected holdup of the peer-reviewed publications.

    Chapter 30 gives a brief description of the 102 site which is more Homo naledi. As it not supposed to be public yet, I’ll just give my pithy summary: “wow.” There is also an epilogue written by Hawks which ends with “Here we go again.”

    1. Adam Benton says:

      For them to be the relict population some are now describing them as, there should be “older” H. naledi. Or at least, older things on their lineage. As such, it would be interesting to investigate whether the Dinaledi chamber at this 102 room are contemporary.

      1. Mike says:

        More details about Homo naledi including what they found at site 102 were given by John Hawks at:

        http://www.bbc.co.uk/programmes/b08n1y37

        I did not want to say when I made my first reply that site 102 is another group of Homo naledi which I learned from reading chapter 30 of the unpublished book by Berger and Hawks. But since that is now out: “Almost Human” claims that they found “large parts” of an adult male’s skeleton including a skull. They found a bone from another adult and remains from what think are children. The book claims the skull is nearly complete and includes the parts that hold the tear ducts.

    1. Adam Benton says:

      A young date has been hinted at by some analysis, but since it didn’t cover the entire skeleton I wasn’t too sold on it. Would be interesting to know an unrepresentative sample arrived at a correct conclusion. But of course, we’re just going to have to wait for the actual date to be published.

    2. Mike says:

      That YEC is one of the few who occasionally know what he is talking about, an extreme rarity with creationists. I once read “Understanding the Pattern of Life: Origins and Organization of the Species” by him that ironically could be used to make a damn good case for evolution.

      1. Mike says:

        I forgot to mention that Todd Wood, the above mentioned YEC, seems to have an odd omission in his knowledge. His blog post linked to above make it seem like he thinks that they been keeping the second Rising Star site a secret when its existence was blogged by John Hawks way back in 2014. Now they certainly have not been giving very much details on it, but that is hardly a break with the m.o. of Berger’s team. After all they publicly announced the existence of the original chamber nearly two years before providing substantive details of what was found when they published in eLife.

  3. marc verhaegen (@m_verhaegen) says:

    Naledi’s curved fingerbones indeed suggest they climbed trees, arms overhead, but there is no evidence they made tools more than chimps do. Berger cs anthropocentrically place naledi into Homo, but all humanlike traits of naledi are not human-derived, but hominid-primitive, e.g. chimp fetuses have humanlike feet which become handlike near birth, and at no stage in our fetal life humans have apelike feet. In ths same way, naledi’s hands are more primitive (as in monkeys & humans), without the extreme lengthening of gibbons or orangutans (relative hand lengths: gorilla & human < naledi < chimp & bonobo < orang & gibbon).
    Naledi might well have been "upright" (which is not the same as "bipedal"), but not for running bipedally: ostriches & kangaroos have very narrow feet with long & strong middle digital rays, unlike flamingoes, grebes, ducks, penguins, australopiths, fetal chimps, humans etc. Naledi fossilized in mudstone, which forms in stagnant waters (P.Dirks). Lowland gorillas & bonobos sometimes wade bipedally in forest swamps, but naledi seem to have done this more frequently, google "bonobo wading". Naledi didn't bury their dead deliberately (as Berger cs assume), but they simply died where they often fed: in wetlands & forest swamps (later the underground eroded into caves).
    Another possibility: if naledi is (only) 300,000 or so years old, and if their bones still contain detectable DNA, I wouldn't be surprised if naledi's DNA resembled chimp or bonobo DNA more than it resembled human DNA (but IMO it would probably resemble human DNA more than gorilla DNA).
    IMO, naledi is only one of the many S.African australopiths (sediba, africanus, robustus), possibly more akin to Pan than to Homo.

  4. Ram Dusk says:

    I had a chat with John Hawks about the “Homo” naledi at September 12, 2015 in which I confronted him about all the preposterous data that they released (burial ground (by a fist size brain primate…) of mostly adult females and young specimens) and offered a better analysis of the finding which he thought was not a bad theory and as we continued the discussion he eventually blocked me (I have screenshots of the conversations).

    What I told John Hawk is that I think that he is taking part in the biggest scientific cover-up in latest history of an inconvenient truth: the “burial ground” is a solid case of repeating escapees dying of CO2 poisoning as they are fleeing deep into the cave to avoid acts of cannibalism performed by males who with their brother shoulders couldn’t get through the last shaft.

    The H. naledi media charade started at September 10, 2015 one day after September 9 2015 the day that National Geographic officially becomes the property of Rupert Murdoch’s News Corp for a $725,000,000 bribe to the entrusted scientific organization after 127 years of being staunchly non-profit magazine and scientific organization.

    The takeover started 2 years earlier when the cannibalistic crime scene was found, I urge you to research “News Corp” and Australian media mogul and climate change denier Rupert Murdoch in order to understand the total “eyeballs” reach and the domination of thoughts that the Rupert Murdoch minion gang has.

    A Wikipedia page was also released: “Homo naledi is an extinct species of hominin, which anthropologists first described in 2015 and have assigned to the genus Homo. In 2013, fossil skeletons were found in South Africa’s Gauteng province, in the Rising Star Cave system, part of the Cradle of Humankind World Heritage Site. As of 10 September 2015, fossils of at least fifteen individuals, amounting to over 1550 specimens, have been excavated from the cave.”

    This is one of many examples of paid scientist that cover-up finding to keep their job, me and my team have confronted the Berger creature over every media publication and article he published and his new religion and the media charade of the naledi died few months later.

    1. Adam Benton says:

      I’m not completely sold on the burial idea either. There’s definitely a lot more information on the geologic context, as well as the fossils, that needs to come out. Hopefully all these rumblings about new finds can shed some light on this. That said, I’m not sure the evidence supports some of the specifics of your idea either. For instance, the holotype of the species is most likely male. Maybe they were just a really keen cannibal?

      And whilst there may be some room for debate in these findings, I’m not quite sure that counts as a cover-up. Although Rupert Murdoch is definitely an ass.

      1. Ram Dusk says:

        Thank you for the reply, here is what i think is an important discussion about the “Homo” naledi:

        Placing the finding in the right context:

        I think the cave is a crime scene portraying repeated acts of hominid cannibalism utilizing members of their own species as livestock that resulted in the first evidence for repeated acts of organized cannibalistic attacks by the ruling gang of males (same as the chimpanzee and as the CHLCA).

        The specimens are similar in size and many properties (including the skull) to the Siamang (Symphalangus syndactylus) but unlike the Siamang every primate after the Hylobatidae shows strong dimorphism.

        Context: A description of the scenery AS IT WAS DISCOVERED and not as it’s changing now (we have documented the people that were present at the time of discoveries):

        The cave is made of a wide main entrance on the surface of the ground going down in a wide passage for about 45 meters (~150’) in ~30 degree slope leading into the first narrow passages leading into a first chamber leading to second passage leading to a second and last chamber where the remains were found:
        To enter the first chamber you have to crawl and squeeze through a horizontal ~5 meter (~16.5’) passage with an average width of 25 cm (~10”).

        From the entrance of the chamber you have to cross about 15 meters (~50’) of horizontal surface and then to climb about 20 meters (~65’) in ~60 degree angle to reach the second passage leading to the last chamber
        The only access to the last chamber is from the first chamber through a narrow, vertically oriented “chimney” or “chute” measuring 15 meters (~40’) with an average width of 20cm (7.9”).
        The fossil-bearing chamber is ∼30 meters (~100’) below the surface and ∼100 meters (~330’) away from the present, nearest entrance to the cave.

        Note 1: Limited amount of Oxygen and long CO2 replenishment period: In the death chamber there is no air ventilation other than the two narrow shafts that leads to the chamber of death.

        Note 2: Pitch-black journey: Except for the first 10 meters that are near the cave entrance the rest of the rout is pitch-black.
        The crime scene (evidences): Many “slender” victims mostly females and few youngsters, and even one “very slender” adult male.
        The victims entered the cave at different occasions in different times.

        The crime (circumstantial reconstruction):

        The “slender” victims mostly females, and few youngsters and even one “very slender” adult male where all chased there by the males of their own kind which had the intention to eat them.

        It was the last chamber that they could escape into when chased; one that the males could not enter with their wider shoulders.
        Suggesting a smaller degree of dimorphism which suggests that a single male could not have attack a female alone with accordance to the second rule of the chimpanzee’s fight club: You do not attack unless you have numbers on your side: which reduce chance of injury for individual attacker as factor of the total number of attacking cannibals e.g. 2 against one victim = 50% chance of injury (50% higher EROEI), 10 against one victim = 10% chance of injury (90% higher EROEI) which means the male gang system was well established in that primate.

        The slender victims enter the chamber after at least a 100 meter of chase in total darkness heavily breathing and died from CO2 poisoning within few hours.
        This explains why the remains of the individual were found side by side (like in a graveyard): They preferred to lay down beside other corps (which arrived there for the same reason sometimes many years prior to their arrival and died of the same reason) that at the time due to the dry and sterile conditions of the cave the past attacks victim’s bodies were probably quite preserved. This also explains why there was no evidence of cannibalism in the chamber: Not enough time before they ran out of oxygen as they were slowly losing their conciseness and die. It was much “nicer” death then being eaten alive by the males lingering outside their chamber.

        To summarize:
        Contemplating the chain of events that could have brought these individuals in to that challenging location, the scenarios that seem the most compatible are that the first chamber (not the last chamber of death) was either a shelter or a temporary livestock pantry. We can assume rather confidently that the option of a burial site is highly unlikely regarding h. naledi’s brain size and structure. And moreover, even if indeed they had had the sufficient mental complexity that would have enabled them to develop burial rituals, the immense challenges that this site imposed and principally the drastic size limitations (for males to reach while carrying a slender body to the vertical shaft of the death chamber) and the pitch-black darkness (no evidence of fire) revokes almost any probability that this theory might have had. It is just too far-fetched.

        And that is why you should look into the reason why such theories are in place for the consensus to thrive on the narrative which cancels the social structure of ruling class of males (and not in the context of the crap pc sjw context) as responsible for the killing rather portraying them as compassionate and responsible for the ultimate act of empathy burial (http://news.nationalgeographic.com/2015/09/150915-humans-death-burial-anthropology-Homo-naledi/).
        Consider that:

        What were they eating? or to be more to the point, what was available to a longer legged 1 meter tall gibbons like animal with weak jaws and teeth that could support their nutritional needs?
        According to the dental specimens and jaw structure, it appears as though the H. naledi were not adaptable carnivores, although their morphology and its resemblance to that of modern Siamang seems like one that would require a rich diet.
        So what can you “chew on” which you can’t cook (since you didn’t yet learned how to use fire) that have all the nutrition you need in times of nutritional deficits?

        The plausible answer is cannibalism: the soft meat of babies, youngsters and young females can be easily consumed even with frugivore teeth and jaws.

        You should also consider this as a case of storing livestock. Utilizing members of their species as livestock enabled them an easy transition from the tropical forests to open savannas (having your nutrition resources migrating with you, increases your fitness dramatically).
        The halt in physical evolution since our last common ancestor with chimpanzees until around 2-3Mya in the homo genus was in contrast to the obvious need to adapt physically in order to utilize the different types of available food sources and shelters, during the periods as the forests retreats or as they migrated to woodlands and latter savannas. This may also hold the key for the frequent amount of reproduction cycles in the human genus when comparing them to other primates.

        You cannot ignore the fact that females in the human lineage have livestock features: The accelerated reproduction cycle like in chicken, the oversized milk tanks like in in cows, the excessive fat tissues as in farm pigs (although they didn’t live in the cold areas yet) and the cute face of a puppy in adult females (to diffuse male aggression and maybe survive another day).

        And there are many more evidences from observations of current living ancestors and fossil record that completely debunks commonly accepted theories.
        Here is a short list:

        Hypothesis regarding the loss of bodily hair: Ignoring the evidence that no other animal that lived exclusively on or above the surface of the African savannas and woodlands have lost its hair, feathers or scales.
        Loosing hair for cooling: Hairy animal sweats as some hoofed animals (camels, horses, and the Hippo (relative of the warthog (Suidae))

        The constant growth of hair on our head: Only one other animal from the Suidae family that lives in barrows in the forests, woodlands and Savannah’s of Africa have similar haircut (for protecting the large skull when crawling in dirt and stone tunnel) Ignoring evidences of Hominidae hybridization with members of the Suidae family (their barrow-mate), as profoundly described by Dr. Gene McCarthy in his very informative website called Macroevolution.net

        The hypothesis regarding development of tools: Not considering that It make more sense for primates that lived in barrows for few millions years (~6Mya-~3Mya) that digging or extending existing barrows in the woodland and savannas of Africa was the trigger for the early hominid axe like tools, which needed a strong opposite thumb of a tree swinger/climber for the thrust (similarity between the hands of early Hominidae/Hominids, homo and Hylobatidae), this digging mediums in time have turned to the rest of the tools (axes, spears etc.)

        The unreasonable hypothesis regarding the shift in diet around ~2-3 million years ago: Our closest relatives the chimpanzee ate meat as early as ~7 million years ago. And what kind of meat a frugivore can bite with its relatively weak jaws, without using fire to soften it?

        Ignoring the fact that Hylobatidae and Symphalangus are outgroup for all of Hominoidea while Pongo, Gorilla, Pan Troglodytes and humans are sister groups hence breeds. All models of human disciplines should include the outgroup especially the Siamang as a reference group for NORMALITY: Our outgroup members the gibbon like creatures are the only species in our lineage that reached true achievements:
        The fastest and most agile of all tree-dwelling, non-flying mammals, but also the master of conservation of energy by using ricochetal brachiation as locomotion strategy (swinging) and by swinging and hanging from branches the early “swingers” have managed to “stand upright” and to developed bigger brain supported by neck centered to gravity.

        The true evolution of intelligence and the real first leap forward was the developed cognition that could calculate complex laws of physics and thermodynamics (angular momentum etc.) while moving in speeds of 50 kilometer per hour in the complex environment of the forest canapé while achieving a consent of energy surplus (due to the energy efficiency of swinging) and more….

        1. Adam Benton says:

          These are all interesting ideas and nothing that would necessarily be wrong apriori, although I don’t think the evidence is there to support it yet. However, it does carry with it several predictions that can hopefully be tested against future finds, like this alleged new chamber. For example, there should be notable sexual dimorphism in the species. A lack of males in these narrow spaces. Evidence of cannibalism outside said spaces. It will be interesting how future discoveries relate to this.

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