PLEASE NOTE: Based on subsequent analysis, I have changed my mind on this fossil. Please find my new thoughts here.
Social media has been abuzz with reports of a newly-discovered ancient relative of people. Named Homo naledi, this “new species” is supposed to shed light on the supposed evolution of human beings. One news report said the discovery “…may alter ideas about the human family tree.” Of course, we’ve heard that before. It seems that every major discovery related to the supposed evolution of humans is said to radically change our view of how humans came to be. While this discovery is very, very interesting, I seriously doubt that is has anything to do with people.
One of the things that makes this find so interesting is where the bones were found. They were found in a cave more than 80 meters from its entrance. Even more intriguing, the chamber in which the fossils were found was accessible only through a narrow chute. The chute was so narrow that most paleontologists couldn’t fit through it. Indeed, in order to excavate the fossils, the lead investigator (Lee Berger) had to put out an advertisement on social media. It called for “…tiny and small specialised cavers and spelunkers with excellent archaeological, palaeontological and excavation skills.” There were 57 people who answered the ad, and six women were chosen from that group. They excavated the bones, while the other members of the expedition watched on video.
In the end, the paleontologists think they found fragmentary remains of at least 15 individuals. The picture above shows a partial composite skeleton that was made from these different individuals. In one of the two scientific papers written about the find1, they say that this composite skeleton represents the remains of a new species. Why? Because it contains a lot of traits associated with the genus Australopithecus, which is supposed to be an early ancestor of human beings. However, it also contains traits that are more like those of modern humans. Because of this mix of “primitive” and “modern” traits, it is thought to be a new species in the supposed evolutionary history of people.
While there is certainly a mixture of traits found in these fossils, I seriously doubt that they belong in the genus Homo (the genus that contains human beings), and I seriously doubt they are related to us in any way.
Now please understand that I am not a paleontologist. I am not even a biologist. I am simply a nuclear chemist who has taken an interest in the creation/evolution controversy. As a result, you need to take my comments for what they are worth. Nevertheless, as I read the scientific papers, I kept wondering how the authors could claim that this is a single species or that it belongs in the genus Homo.
Let’s start with the issue of the genus. One of the major characteristics that is used by paleontologists to classify these kinds of creatures is the cranial capacity (the volume of the part of the skull that houses the brain). While there were no complete skulls found among the fossils, four partial skulls from different individuals were used to construct several possible composite skulls. Their cranial capacities were between 465 cubic centimeters (cc) and 560 cc, which are consistent with the range of cranial capacities found in the genus Australopithecus. They are smaller than the cranial capacities generally associated with the genus Homo. In addition, the skulls do not have the protruding nasal bone expected for the genus Homo.
Of course, there is more to the skeleton than the skull, but once again, most of the other skeletal features don’t line up with what we expect of genus Homo, either. Consider, for example, the femur, which is the leg bone between the knee and the hip. The top of the bone ends in a small ball that is attached to the rest of the bone by a long neck. In addition, there is a protrusion that points backwards. Once again this is very characteristic of the genus Australopithecus. A femur characteristic of genus Homo has a larger ball, a smaller neck, and a protrusion that points the other way. Similarly, the shapes of the hips and the ribcage are characteristic of the genus Australopithecus, not Homo.
So why do the authors assign these specimens to genus Homo? Partly, it is because of the feet and hands. While the curved finger bones are, once again, characteristic of genus Australopithecus, the thumb and some other details of the hand are quite different from what you expect from genus Australopithecus. However, they are also quite different from what is found in genus Homo. The foot is more like what is found in the genus Homo, but once again, the toes are curved, which is more consistent with the genus Australopithecus.
Since the vast majority of the skeletal remains are more consistent with genus Australopithecus and the few similarities to genus Homo are minimal at best, I think the assignment to genus Homo is not really justified based on the remains themselves. I actually think the real reason these fossils have been called “human-like” is found in the second paper related to the fossils.2 In that paper, the authors try to make the case that because these fossils were found in a hard-to-reach chamber of a cave, they were the result of ritualistic burial, which is a uniquely human characteristic.
This, however, is even more of a stretch. There are many possible reasons for an assemblage of fossils being found in a hard-to-reach part of a cave, and burial seems to be the least likely one. Based on the map of the cave as given in the paper, in order to “bury” the bodies in the chamber, a living individual would have to drag them while executing a complex climb in a dark part of the cave. Also, the paper clearly says that there is no evidence of trauma to the bodies, so the idea that they could have been dropped down a chute to land on the floor of the chamber seems rather far-fetched. Of course, as the authors point out, it’s possible that the cave was different back then and the chamber was easier to access. If that’s the case, however, there’s no reason to suspect that there was anything “special” about the chamber back then. Thus, there would be no reason to think that it was a burial chamber.
Here’s the other problem I have with the conclusions of these papers: it’s not clear that the fossils all come from the same species. One of the partial skulls, for example, is noticeably different from the others. It is much more rounded than the others, and it has a much higher forehead than the others. It’s hard to understand how that skull can be from the same species as the others. If there is a mixture of species in this fossil find, then the composite skeleton could also be a mixture of species, which makes any conclusions drawn from it useless.
So what does this non-paleontologist think of these fossils? Like the other members of genus Australopithecus, I think they are the remains of extinct varieties of apes. Most likely, it is a collection of fossils from more than one variety of extinct ape. I don’t see any justification for thinking they are part of a supposed human evolutionary line, and I certainly don’t find any reason to put them into genus Homo. Of course, I am not an expert in this field, so take that for what’s it’s worth.
I will leave you with a quote from an expert, however. Primate anthropologist Dr. Esteban Sarmiento wrote something in the journal Science five years ago about another supposed human ancestor that had been found. However, I think his quote applies to this find as well.3
…it is curious that in a century-old race for superlative hominid fossils on a continent currently populated with African apes, we consistently unearth nearly complete hominid ancestors and have yet to recognize even a small fragment of a bona fide chimpanzee or gorilla ancestor.
In my opinion, the reason is simple. No one wants to find a chimpanzee or gorilla ancestor. However, everyone wants to find a human ancestor!
1. Lee R. Berger, et al., “Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa,” eLife DOI: http://dx.doi.org/10.7554/eLife.09560.001, 2015.
Return to Text
2. Paul HGM Dirks, et al., “Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa,” eLife DOI: http://dx.doi.org/10.7554/eLife.09561, 2015.
Return to Text
3. Esteban E. Sarmiento, “Comment on the Paleobiology and Classification of Ardipithecus ramidus,” Science 328:1105, 2010.
Return to Text
30 thoughts on “Homo naledi: Human Relative? Probably Not.”
Fascinating stuff! Thanks for the great article Dr. Wile.
I want to point out that in paragraph five there is a small mistype:
“Now please understand that I am not a paleontologist. I am not even a biologist. I am simply a nuclear chemist *whose* has taken an interest in the creation/evolution controversy.”
I think it’s pretty cool that we’re still discovering treasures like these! We think we know so much and then we discover something that we haven’t encountered before.
Thanks for pointing out the typo, Kendall!
Always appreciate your perspective and research! I’m curious about paragraph 12, 2nd sentence…”Like the other members of genus A…, I think..” Does this imply YOU are a member of genus A…?
Hehe. It took me a minute to get that. I guess it should read something like, “I think they are like the other members of genus Australopithecus, which are extinct varieties of ape.”
A very interesting article Dr Wile. Like you, I am no expert in paleontology but I did see and work with a large number of primates in my younger years. Most of the non human primates I have seen have very large defensive canine teeth.
When I looked at the BBC video the upper canine tooth was extremely broad but blunted. I don’t know if teeth were found in the skull or not, but I suspect they were found separately and placed in the skull. I am very suspicious that the canine teeth were either blunted intentionally, or an incorrect tooth was placed in the socket for the canines.
The roots on the canines of non human primates are huge. In most cases the root is as long as the canine itself. Since that is the case it would be easy to measure the root depth on the canines of the skulls they found to see if it is extremely deep and large. If it is, the skulls belong to apes not humans.
I will try to post a link to the video below.
The video link works, Bill. Thanks. The paper doesn’t specifically say that the teeth were found in the skull, but the pictures in the paper show them in the skull. Generally, there would be a note if the teeth weren’t found in the skull, so I would think they were.
based on other You Tube videos I think you are correct that teeth were found in the skull. However on the video’s it looked like only portions of the lower and upper jaw were found with teeth. The skull shown on the video I referenced appears to be a composite from several pieces not a complete lower or upper jaw.
I still think the area of the canines looks unusual. Perhaps they did not get it quite right in the reconstruction.
This is a more comprehensive video on the find.
Dr Wile, I really thought your quote by Dr Sarmiento was extremely interesting and revealing.
“…it is curious that in a century-old race for superlative hominid fossils on a continent currently populated with African apes, we consistently unearth nearly complete hominid ancestors and have yet to recognize even a small fragment of a bona fide chimpanzee or gorilla ancestor.”
I think that quote reveals the fact that there is a significant amount of prestige and financial gain that goes along with finding hominid fossils while there is no incentive for finding chimp or gorilla fossils. When Lee Berger told National Geographic he thought he had found possible early hominid fossils he apparently received a large amount of financial assistance to proceed with uncovering the find. Obviously he would not have received a dime to uncover chimp or gorilla fossils.
Given this strong financial incentive, do you think there would be a greater likelihood that a team of paleoanthropologists would try to construct a more human like ancestor from the bone fragments that were found? If there had been the same financial incentive to find ape bones, do you think they might have assembled the bone fragments in a different manner to reveal a more ape like creature?
A quote from the National Geographic article titled This Face Changes the Human Story. But How? by Jamie Shreeve follows. “You could almost draw a line through the hips—primitive above, modern below,” said Steve Churchill, a paleontologist from Duke University. “If you’d found the foot by itself, you’d think some Bushman had died.”
I thought that was an interesting quote. What if bushmen lived in the cave and hunted apes of some sort. Wouldn’t the same mix of bones be found if some of the bushmen died or were buried in the cave and also left bones of their ape prey in the same area? Depending on what bones remained or were selected, there could be quite an interesting mosaic of human and ape features integrated into the reconstructed skeleton. I know this is only speculation, but it would explain a lot of the findings.
Thanks once again for the article. It has made me very curious about these findings.
I do think there is a lot of incentive to “humanize” any apelike fossils to include them in the human evolutionary line. I also agree that your proposed scenario is plausible. After all, to my untrained eye, it does look like there is a mix of species there. The authors in the paper seem to think that because the teeth are all similar, there is only one species represented there. However, you can’t know that the teeth belong to every fossil in the find!
However, I would disagree with Shreeve’s analysis of the foot. The toes are definitely curved, and that’s not a trait you associate with any man.
Thanks for the reply Dr Wile. Did you find a source that said the toes were curved or are you referring to an image that shows the curvature.
You can see it in the image of the foot presented in the paper, and the authors describe the toes as “moderately curved.”
Dr Wile, These two quotes are somewhat confusing to me. The first suggests curved phalanges that you mentioned. As you know the word can refer to either hands or feet. The photo of the foot only has phalanges on the large toe. The others are missing. The first quote below is grouped with information about many areas. The reference could be to the phalanges of the hand since other interviews with the researchers do not suggest curved bones of the feet. The second quote is more specifically about the feet and describes the only differences between H. naledi and H. sapiens. There is no mention of curved phalanges.
“The phalanges are moderately curved, slightly more so than in H. sapiens. The only primitive anatomies found in the foot of H. naledi are the talar head and neck declination and sustentaculum tali angles, suggestive of a lower arched foot with a more plantarly positioned and horizontally inclined medial column than typically found in modern humans (Harcourt-Smith et al., 2015). ”
“The foot of H. naledi can be distinguished from the foot of H. sapiens only by its flatter lateral and medial malleolar facets on the talus, its low angle of plantar declination of the talar head, its lower orientation of the calcaneal sustentaculum tali, and its gracile calcaneal tuber.”
Image C in Figure 9 looks curved but those are metatarsal bones. The phalanges look fairly straight to me. Perhaps you have some other information about curved phalanges that I missed. The thing that I think is very unusual about the creature is that the hands are well adapted for arboreal environments while the feet are human like. It makes little sense to me that a creature with an ape pelvis would have human like feet since that type of pelvis would necessitate a swaying gait. It also makes little sense to me that a creature so well adapted to tree dwelling from the pelvis up would have feet that would be so poorly suited to tree dwelling.
Of course the teeth are also still an area of concern. It looks to me like the skull was assembled so that the upper and lower incisors and canines directly appose each other. That doesn’t make sense to me. I have a dental appointment Monday and plan to take some of the dental photos with me to see what my dentist thinks of the teeth.
Thanks again for your helpful commentary.
The first quote you give is in the section that discusses the foot,so the moderately curved phalanges are the toes. The second quote is about the foot proper, which doesn’t include the phalanges.
The metatarsals are more curved than the phalanges, but they are all curved more than in humans.
Intelligent disussion, thanks all. Yes, fascinating, fabulous, fantastic fossils, but no burial, of course, and possibly Australopithecus naledi rather than Homo. Prof.Sarmiento (following others, incl. my Hum.Evol. 1994 & 1996 papers) is correct IMO: most humanlike features in australopiths are probably not derived but primitive: low ilia, flat feet + long big toes (as in prematal chimps & gorillas), not-lengthened hands, broad fingertips, small canines, thick enamel etc. Apes & apiths OTOH lack uniquely-Homo-derived features: external nose, large brain, very long legs etc. Many PAs still follow the conventional idea that ape->human = forest->plain = quadru–>bipedal, but we don’t descend from chimps: both Pan & Homo had the same (more apith-like) last common ancestor c 5 Ma. The naledi fossil seems to be morphologically closer to this LCA. The remarkable combination of flat feet (duck, flamingo, pinniped, vs ostrich, zebra, lion) + curved hand (more than foot) phalanges is to be explained by an aquarboreal locomotion: wading-swimming + hanging-climbing in swamp forest or wetlands (not unlike lowland gorilla wading bipedally in forest bais for sedges & frogbit and climbing in the branches above, google Ndoki gorilla). Many of these swamp-dwelling naledi must have died in the swamp, buried in the mud, perhaps later the swamp dried out, and sank into the cave?
FWIW, I’d think naledi is more closely related to Pan than to Homo, and more to Homo-Pan than to Gorilla, google human evolution marc verhaegen, or researchGate marc verhaegen.
Dr Wile, once again I appreciate your reply. As I write this post please be aware that I am not trying to be critical of you personally in any way. I believe you have written as accurately as you could based on the information in the article. I do believe the article is somewhat confusing when it describes the curvature of the toes.
When I looked at figure 9 that showed the foot of H. naledi, I compared it to the foot bone illustrations of modern humans. The more I looked, the more convinced I became that the foot of H. naledi could easily fit within the normal variation of the human foot. The first phalanx has a curvature on the ventral surface, which humans also have, but the bone itself looks very straight to me. It is very similar to the human first phalanx.
The lead paleontologist, Lee Berger, was interviewed on Cliff Central.com on Sept. 18 and said in the interview that the H. naledi foot was identical to a human foot. The phalanges are part of the foot, so he should have stated any differences in them also if they were present. There was no mention of curved toes.
My tendency is to believe the foot is fully human while the area of the pelvis and above is clearly ape like. If we use the evolutionary scenario of deep time, anything could have happened in those “millions of years” including both apes and humans wandering into the cave and dying there for whatever reason. I think another possible explanation for so many ape like bones being in the cave is that a troop of apes went into the cave to escape a torrential rainstorm and were forced to retreat deeper into the cave by the rising water in the anterior chambers. Once confined to the small posterior chamber, they may have simply suffocated. That makes more sense to me than apes burying their dead.
Lee Berger said during the interview that there were more findings that he was not ready to reveal at this time. In addition, there are many more bones remaining in the cave to be excavated. Hopefully more feet and toe bones will be found so that the picture will become more clear. In the meantime, if we have a foot identical to a human foot, it is most logical to me that it is probably a human foot.
The link to the interview follows. The comments about the foot begin at about the 4:30 minute mark.
Perhaps further investigations will clarify the issue, Bill. Had the foot been “identical” to a human foot, the toes would not have been described as “moderately curved.” In addition, the picture doesn’t look identical to human feet, because the toes are moderately curved. Most likely, the scientist being interviewed was overstating the case. That’s something you can do in an interview, but not in a scientific paper.
I think you are correct Dr Wile. I emailed an individual who is doing an independent study. His quote follows. “However, the phalanges are quite curved – not as much as a chimp, but much more than the average human. An in-depth paper on the foot is coming out very soon.”
I guess I was putting too much confidence in the comments of Lee Berger. I plan on requesting a copy of the paper from the researcher. As you said, further investigation will help clarify the issue.
“While there is certainly a mixture of traits found in these fossils, I seriously doubt that they belong in the genus Homo (the genus that contains human beings), and I seriously doubt they are related to us in any way.”
Possibly due to being a nuclear chemist as opposed to a primatologist or a paleoanthropologist. We’ve heard that before (paging Jonathan Sarfati).
“…it is curious that in a century-old race for superlative hominid fossils on a continent currently populated with African apes, we consistently unearth nearly complete hominid ancestors and have yet to recognize even a small fragment of a bona fide chimpanzee or gorilla ancestor. ”
Simply by saying “one unearths lots of hominid fossils” and “one does not find any chimpanzee ancestors” simply means that it is easier to find a hominid fossil than it is another.
Most ancestors of chimpanzees lived in a jungle environment and that it’s far harder to conduct a full dig in that kind of environment than it is to, say, send a team of pint-sized female anthropologist to go cave-hunting.
You could be correct on your first point, Parsoni. I am not a primatologist or a paleoanthropologist, so I could be wrong. Of course, we have all heard “new human ancestor” before as well (paging Ida).
Please note that I did not say “one does not find any chimpanzee ancestors.” Primate anthropologist Dr. Esteban Sarmiento did. We find all sorts of fossils of animals that lived in jungle environments. There’s no reason to think chimpanzee ancestors or gorilla ancestors would be any harder to find.
The issue I have with your comments and your argumentative style in general is that it, like Jonathan Sarfati I mentioned, makes certain assumptions before anything else.
Homo naledi is currently estimated to be about 2.5-2.8 million years old, which makes it slightly younger than australopithecus.
Most of your argumentation revolves around the debate as to whether it is a hominid or an australopithecine. However, given the closeness of the two, the mix of characteristics and the possibility of an intermediate form make it likely where the Rising Star steam estimated it to be.
Which leads me to the biggest part of my argument. The problem I have often with creationist argumentation, especially when it comes to hominid evolution is that it largely assumes that merely because it shares some characteristics of the last genus and some of the one in front means that by default it is an invalid taxa. While we can’t track every single birth, we can assume where it is with a high degree of accuracy.
Which brings me back to your quote. The reason we don’t do this is because the common ancestor between chimpanzees and humans lived far before the estimated find. Primatology, especially that related to chimpanzees, does not concern itself with hominids and the doctor’s point is moot as one would not expect to find chimpanzees beside hominids and expect them to look identical.
You said: “Their cranial capacities were between 465 cubic centimeters (cc) and 560 cc, which are consistent with the range of cranial capacities found in the genus Australopithecus. ”
Homo naledi is claimed to be an immediate offshoot of the australopithecine lineage. It’s to be expected that they would have similar cranial capacities while still having different traits throughout the body (as you mentioned in your statement of the shape of the various limb descriptions).
To continue on my previous point, primatology suggests that the common ancestor between chimpanzees and the hominid lineage lived before 4.4 million years old (before ardipethics ramidus).
One would not expect to find any chimpanzee lineages along this line, as it would be a completely different offshoot.
Also, one could argue the technique for unearthing hominid fossils as well as the availability of resources for hominid research could be the reason for this. It doesn’t in anyway discredit human evolution.
Also, Dr Jay, could you do me a small favor and please link me to the paper by Dr Sarmiento? I’d like to read the full text.
edit: ignore that “technique” claim I made.
Parsoni, my discussion revolves around the debate as to whether it is a hominid or an australopithecine because that’s an important debate and is by no means settled. You might see evidence of an intermediate between australopithecines and humans, but I don’t.
I am not at all saying that because it shares some characteristics of two genera means it is an invalid taxa. I am saying that it looks to me more like an australopithecine than anything else, and there is very little reason to classify it in the same genus as humans.
I understand that some want very much for this find to be an immediate offshoot of the australopithecine lineage. However, the nature of the fossil doesn’t seem to indicate that at all.
One might not expect to find any chimpanzee lineages along some hypothetical evolutionary line, but as Dr. Esteban Sarmiento points out, they should be all over Africa, but for some curious reason, they are never found.
I am sorry the detailed reference isn’t enough for you to find the article. Here is the link.
“One might not expect to find any chimpanzee lineages along some hypothetical evolutionary line, but as Dr. Esteban Sarmiento points out, they should be all over Africa, but for some curious reason, they are never found.”
Though this might be true (and if one doesn’t trust only one researcher’s words, might not) this does not discredit the fact that we’ve found a hominid/australopithecine/whatever-you-call-it.
“I am saying that it looks to me more like an australopithecine than anything else, and there is very little reason to classify it in the same genus as humans. ”
You said specifically that it shares several australopithecine features and several hominid features. Though I’ll have to research further to see the exact skeleton itself as well as a rough draft of the lineage suggested by paleoanthropologists, it’s not enough to simply state that “it is not a homind”.
Parsoni, paleontologists have found something. However, what it is hasn’t been determined. In fact, as discussed here, it might not even represent a single species.
I did not say that these fossils share several australopithecine features and several hominid features. In fact, I said, “Since the vast majority of the skeletal remains are more consistent with genus Australopithecus and the few similarities to genus Homo are minimal at best, I think the assignment to genus Homo is not really justified based on the remains themselves.”
I am not just stating that this is not a hominid. I am giving several reasons as to why it is probably not a hominid.
The big problem I have with your argumentation is that you haven’t cited exactly where the species lies along a specific lineage. As previously said, it is a cousin of a previous human ancestor, not directly on the line.
Without this specific lineage, we can’t properly analyze how it was classified.
Once we get that, we’ll be able to make a more enlightened investigation.
Furthermore, where did you get that figure that “almost all were consistent with australopithecine” and how did they come to that conclusion.
Btw, Jay, I apologize for being rough in my earlier comments. I have a certain degree of impatience.
The reason I believe this is because I highly doubt that the same people who have intimate first-hand knowledge of all the skeletons in the hominid and australopithecine family would omit such a thing. There’s probably more to it than simply “it looks more like that, therefore it’s more likely to be this.”
I see the logic in it, I just want to dig a little deeper.
I am sorry that I didn’t make myself clear, Parsonsi. Since it is hard to determine whether or not these fossils all represent one species (the skulls especially seem to indicate the fossils might represent a mix), it is very hard to determine where they might fit in some hypothetical lineage. However, if I were forced to do so based on the data available right now, I would say that they represent a mix of australopithicines that have different minor adaptations than the few australopithicines already studied.
I get the figure that almost all of the characteristics of the fossils are consistent with australopithicines from the scientific article itself. If you read the discussion and look at the pictures, the vast majority of the characteristics are australopithicine. In this article, I give the skull and femur as examples, but in the scientific article, you can see many more.
I didn’t find you “rough” in your earlier comments. You seem to be genuinely interested in the analysis, which sets you apart from some of the trolls who have attempted to comment on this blog.
I agree that people who have first-hand knowledge of the fossils know more about them than people like me, who are untrained in this area and are simply reading their report and looking at the pictures they chose to publish. At the same time, however, science progresses when multiple people with multiple views examine the data thoroughly and offer their opinions. I have published in the peer-reviewed literature of my field (nuclear chemistry), and I always value when people read my studies and comment on them, regardless of whether or not they are nuclear chemists. Even though they don’t have first-hand knowledge of the experiments upon which I have reported, they can still offer valuable insights.
Comments are closed.