Who is Homo Naledi? An Interview with Christian Paleontologist James Kidder | The BioLogos Forum


(system) #1

On September 10, one of the most significant hominin (human ancestor) fossil discoveries in history was announced. Paleontologist Lee Berger led a team of scientists who found numerous fossil remains of a new species, Homo naledi, in a remote South African cave. As Darrel Falk wrote last week, this discovery could have massive implications for our understanding of human evolution. We asked James Kidder, a paleontologist and BioLogos guest contributor, for his thoughts on the monumental discovery, and he has graciously agreed.

BioLogos: How did paleontologists like Lee Berger determine that these fossils belong to a new member of the genus Homo (instead of a variant of an existing species)? Why not a member of Australopithecus(the genus in which most early hominins belong, including the famous “Lucy” fossil)?

James Kidder: According to Berger’s analysis of the fossil form (Berger et al., 2015), it is similar in size to early Homo (although cranial size, at 513 cc, is on the low end of this range) but the morphology is different from existing forms. There are characteristics of the head that are found in later hominins, such as an angular torus (a ridge of bone extending from behind the head to the back of the head), more extensive brow ridge development, an occipital torus (ring of bone on the back of the head), and sagittal keeling (a ridge of bone on the top of the skull). These are all traits found in Homo erectus (although to greater extent) and not found on any australopithecine. Interestingly, As Chris Stringer has also noted (Stringer, 2015), some of these traits also are found in the 1.8 mya Dmanisi sample, reported a few years ago, suggesting that they are widespread and may appear earlier than originally thought.

Although the face is lightly built, it lacks many of the facial characteristics of the most common gracile in the area, Au. Africanus—no maxillary anterior pillars and a flat clivus, the space between the roof of the mouth and the maxillary sinuses. Additionally, the palate is parabolic, resembling early Homo. The teeth, however, are very small and resemble those of australopithecines.

Below the head, the skeleton is also a mix of traits found on australopithecines and those found on early Homo. The hands are more modern in that there are stronger muscle markings for opposable thumb use and manipulation of the fingers. Also, the thumb is, on the whole, longer. These characteristics are not at modern levels, however and the fingers are long and curved suggesting a link with late australopithecines. The tibia and femur are like those of other early Homo, but the foot and ankle are particularly modern in morphology, with adaptations suggestive of facilitating long distance walking. Oddly, the pelvis seems to resemble the early Au. afarensis in that it is flared. Importantly, while the ribs appear primitive, the vertebrae and, especially their neural canals, are more modern. Expanded neural canals are directly linked with greater central nervous response—better hand/eye coordination, running ability and other similar advancements.

The fossils have not yet been dated. Are there ways to determine where this species fits in our evolutionary timeline even without accurate dating of the fossils themselves?

Not easily. The depositional aspects of this find are similar to those that plague other South African finds. As was indicated in the accompanying article by Dirks etal. (Dirks et al., 2015), this was not a place where these hominins lived. Rising Star Cave system is one of many different cave systems that form when water percolating through the rock dissolves the underlying limestone, creating large cavities under the surface of the ground. Eventually, as more water erodes the surface, these cavities are exposed. Dirks et al. indicate that the bones of H. naledi were carefully dropped in from up above and any decomposition and disarticulation occurred after this. As was pointed out in the Nova special, The Dawn of Humanity, the bottom of the cave is not even visible from the surface. The problem is that we have no idea when they were dropped in. We may be able to date the surface of the cave floor but there is no way to relate those dates to the bones, themselves.

Consequently, the morphological analysis will have to proceed in a systematic fashion, with an examination of which traits are derived or primitive relative to other species of Homo and Australopithecus. Such an analysis can never completely proceed in the absence of a chronological framework, however. We have to have some kind of anchor to tie it to.

Currently, several hypotheses are being examined for how the hominin remains got where they are, including mass catastrophe, deliberate “dropping” and predation. Dirks et al. suggest that the best model involves the deliberate placing of the hominins into the cave mouth simply because they show little to no signs of scavenging or other predatory marks. Whether this means that they were displaying advanced understanding of death and the complex notion of “burial,” as was implied during the Nova special, is not clear. The other hominins in the area may simply have wanted to get rid of the bodies because they did not want them around, a view also espoused by Bill Jungers.

Is there any significance to the location of the finding (in South Africa)? There have been hominin fossil finds before in South Africa, but not many of the Homo genus. Were you surprised about the location?

Yes, there is quite a bit of significance to this find being in South Africa. Since the late 1970s, there have been South African fossil finds that have been touted as being early Homo but the finds have been extremely fragmentary, so there has been no “smoking gun” that firmly establishes early Homo there. Further, the remains that have been found are restricted to one location: Swartkrans Cave, which is less than half a mile from the Rising Star system. Grine, in 2005, suggested that the “incomplete fragments and isolated teeth” found at Swartkrans cannot be unequivocally linked to early Homo. He noted at the time that such a hypothesis, while not unreasonable, simply had no direct support (Grine, 2005).

If the morphology of the H. naledi remains is not in dispute, then the presence of early Homo in South Africa is now clearly established. This is a game-changer because, arguments about Au. sediba’s potential role in the evolution of early Homo aside, it has always been assumed that the evolution to early Homo occurred in an East African context. That may have yet happened, but these finds make that argument harder to unequivocally support.

The other aspect of this find that is so striking is the sheer size of the cache of remains. The material from the Rising Star Cave comprises some 1550 fragments that can be attributed to at least fifteen individuals. Aside from the Middle Pleistocene remains at Atapuerca, in Spain, and the Zhoukoudian Homo erectus remains in China, we have never had a find this large. That these remains are from such a critical point in human prehistory, the transition from australopithecines to early Homo, is simply astounding. These two papers only scratch the surface of what we can learn about human evolution from these fossils.

In what way does this finding confirm the existing scientific understanding of human evolution? This confirms the existing scientific understanding of human evolution in several ways. First, it provides us with yet another example of the mosaic nature of evolution, in which some traits have clearly evolved toward the modern condition, while others have yet to do so. Second, it reaffirms the trend towards modernity that we see in this range of species. As the traits are studied, patterns of evolutionary change can be delineated over time and space. Third, it confirms one of the principle predictions that Charles Darwin made in Descent of Man, that the ancestors of humans would be found near where our closest living relatives, the higher apes, live. Since the early 1920s, with the finding of the first australopithecine skull, that prediction has been shown to be true over and over. This new find, with its suite of modern and primitive traits, also reaffirms what we have thought for the last eighty years: that humans have evolved and share a common ancestor with the modern apes sometime in the late Miocene epoch.

In what way does the finding challenge our current understanding of human evolution?

It challenges it because, as noted above, it clearly places early Homo in South Africa, a place where, up until this point, we haven’t been sure it was there. If we can ever determine the date for these fossils or, better yet, discover other members of this species that can be dated, then we can better understand how early Homo got to South Africa.

One of the things I find somewhat mystifying about the article written by Berger et al. is its complete omission of any mention of the Ledi-Geraru find in the Afar Triangle of Ethiopia that, ostensibly, establishes early Homo at 2.8 million years. This becomes especially important since both the Rising Star and the Ledi-Geraru finds suggest the presence of primitive, australopithecine traits and more modern, early Homo ones, although this is disputed by John Hawks, who suggests that the LD 350-1 jaw cannot be unequivocally assigned to Homo4. Any overarching model of early Pleistocene human origins will have to address these geographically disparate finds.

Editor’s Note: There are many more questions to ask, and much more to be learned from this fossil find. We expect to post more about this in the future.


This is a companion discussion topic for the original entry at https://biologos.org/blog/who-is-homo-naledi-an-interview-with-christian-paleontologist-james-kidder

(Brad Kramer) #2

James Kidder (@Jimpithecus) is available to respond to questions and comments.


(Patrick ) #4

Great post, thank you. Question: does Naledi move back in time characteristics that we consider to be only human traits?


(Roger A. Sawtelle) #5

@Jimpithecus

Thank you for answering questions.

I was interested in Darrell Falk’s statement about what this find says about the importance of cooperation in the evolution of humans. Do you have anything to add?

BioLogos needs to base its discussion of evolution more on actual field studies, rather than genetic studies and theories.


#6

Great post! This material is so interesting! One time I got to meet Viktor Deak, the paleoartist mentioned in the Nova special, at the American Museum of Natural History. It was a behind-the-scenes tour, and it was all quite fascinating.


(ashley haworth-roberts) #7


From what is stated at around 1 hour 33 minutes into this documentary, what clinched these bones as belonging to a Homo species was the shape of its supraorbital ridge.


(Patrick ) #8

But such a little head. Folks use to get all up in arms about having ancestors that looked so ape like. Lucy was far enough away to say she was a transitional species but Naledi is awful close to us. Looking at Naledi, I’ll never again say that Neanderthals didn’t look like us or wasn’t human. Great documentary.


(James Kidder) #9

Sorry. My comments option was not enabled. Not sure. The problem is that we don’t know for sure how old these specimens are. We DO know that we have fossils in the north part of Africa that show characteristics of early Homo at 2.8 mya, so that is what we will go with, for now.


(James Kidder) #10

Well, first, I think that the statement about co-operation is, perhaps, overstated. As Bill Jungers points out, it may very well have been that they just threw the individuals into the cave because they didn’t want them around. That is equally possible. As far as the genetics is concerned, it is as much through it as through the fossils that we understand evolution and how it works. The genetic studies, for example, have given us a pretty good idea of when the branch that became Neandertals split from other archaic Homo sapiens and it is genetics that has reinforced the perspective that there has never been a single, reproducing pair of people that gave rise to the human race. We know this from the fossil material because, as I pointed out in one of my posts of the human fossil record, the Fertile Crescent is remarkably bereft of fossil hominin material. In fact, there is none before the Neolithic and the first anatomically modern humans that we have in the area show up in Israel at around 100 thousand years ago.


(Robinson Mitchell) #12

Bill Jungers’ view that these remains were simply disposed of in the cave has some merit, however the absence of any other trash or detritus in the site, which contains only the h. naledi remains, means that the bodies were not viewed as mere trash to be disposed of. This connotes the possibility that those who placed the remains at least viewed them as something special and apart. Actual burial? Probably not. There don’t seem to be any decorations, jewels or tools buried with the bodies, but this too is unsurprising, as h. naledi may not have been tool users, even though their hands indicate the ability to be toolmakers. Their small brains probably would not have the ability of abstract thinking about concepts like an afterlife or even a spirit. But the fact that the site is clean of trash and contains only hominin remains may indicate that they at least valued the remains of their dead, and points to their inchoate humanity. Could it also point to an inchoate theology?


(James Kidder) #13

Maybe, but you have to remember that there is no indication that these forms were eating meat at this point, so “trash” may have been perishables, which would not survive. I do think that it is significant that they were depositing the human remains into the cave, just not sure that it means more than that. It is possible that there was some sort of ritual before the bodies were disposed of, but we won’t ever know, one way or the other. The fact that there are no carnivore bones in the cave indicates, if nothing else, that even they thought it was a miserable place to get in and out of.


#14

If these creatures simply wanted to dispose of bodies, they sure went to a lot of trouble to do so. It will be interesting to see what else they find in this cave.


(Gregory) #15

“genetics that has reinforced the perspective that there has never been a single, reproducing pair of people that gave rise to the human race.” - James Kidder

Hmm, that’s interesting. I didn’t think palaeos used the word ‘people’ very often and sometimes intentionally not at all (i.e. they usually reserve that term for other ‘social-cultural’ fields). Technically, wouldn’t it be more proper to speak of a ‘pair of persons’ or ‘two peoples’, but not a ‘pair’ of people (from the term ‘populace’)?

One needs at least 3 (and usually many more) to correctly use that word in the ‘group’, ‘community’ or ‘population’ sense meant by most anthropologists, sociologists & psychologists at least that I am aware of, with a few exceptions (i.e. not just colloquial - ‘two people walking on the street’).

Funny also that many anthropologists consider the term ‘race’ an ‘unscientific’ term. ‘Human race’ is not so ‘unified’ as it used to seem. I asked a world leading scholar this question in front of a large crowd and he said simply that ‘race is not a scientific concept.’ Would ‘gave rise to humanity’ be more appropriate, technically for palaeontology too, or is it commonly held in your field of study, James, that there is a single unified ‘human race’ today?

NB: the term ‘human race’ is not used in the KJV, the NKJV or the DRA, but it is used 6 times in the NIV, 9 times in the NTL and only once in the NASB translation: James 3:7.


(Patrick ) #16

Jim,
Just read this. Your thoughts? http://news.sciencemag.org/archaeology/2015/09/dna-neandertal-relative-may-shake-human-family-tree


(Patrick ) #17

Neanderthals polluting air (and their lungs) 450,000 years ago. http://www.nature.com/articles/srep14252


#18

Why do you say that, Roger?


(Roger A. Sawtelle) #19

@Joao

Genetic studies look at the past as indicated by the genes found in different species. It really does not tell us why the differences. Field studies do.

Evolution is about both Variation and Natural Selection. Genetics tells us about Variation, but not about Natural Selection. Field studies can tell us about both.

It can tell us that stickle-backs developed the stickle to protect itself from predators and shed the stickle where it failed to do that. This is a great example of how the environment determines adaption and the form of a species.


(Gregory) #20

In case it helps James feel more welcome to respond to my questions above, even if he doesn’t have the (only) authoritative answer, this prayer was read recently in NYC by/with a rare visitor from the Roman Missal:

O God, who gave one origin to all peoples
and willed to gather from them one family for yourself,
fill all hearts, we pray, with the fire of your love
and kindle in them a desire
for the just advancement of their neighbor,
that, through the good things which you richly bestow upon all,
each human person may be brought to perfection,
every division may be removed,
and equity and justice may be established in human society.
Through Christ our Lord.

Do you affirm “one origin to all peoples”, James?

O God, who show a father’s care for all,
grant, in your mercy,
that the members of the human race,
> to whom you have given a single origin,
may form in peace a single family
and always be united by a fraternal spirit.
Through Christ our Lord.

I’d be glad to hear from James something other than the strictly material ‘origin(s)’ coming from ‘scientific’ palaeoanthropology. How does he synthesize those findings with Scripture?


#21

The Roman Missal is a book that contains prayers, etc for the celebration of Mass in the Roman Catholic Church. The pope is not a “visitor from the Roman Missal.”


(Gregory) #22

Nice catch, beaglelady. “this prayer from the Roman Missal was read recently in NYC by/with a rare visitor” is more accurate. Here I operate roughly 60/40 in English, though it is my native language. So I appreciate your charity, even with language. Were you there (if I remember correctly, you live in or near NYC)?