How many ape kinds are there?



I just read in a creationist newsletter that all apes, from chimpanzee to gorilla to Australopithecus to Ardipithecus, form a single baramin.  I found myself surprised at this claim, fearful that I'd missed some important research breakthrough.  I don't think I did, but I could be wrong, of course.  So I thought I would review the baraminology of apes.

Now you might be wondering, Who cares?  They're apes.  They're not human.  We didn't evolve.  End of story.  Well, they're God's creations, and that makes them important.  If they were important enough to create, then maybe I ought to care about them in some way?  Beyond that, there's a tremendous value to fully understanding the baraminology of groups so similar to human beings.  It's one thing to say that humans aren't related to apes, but it's quite another to explain what the ape kinds actually are and how humanity is not connected.  It's another whole level of evidence and support for the uniqueness of humanity.

So what are the ape kinds?  Last year, I wrote about this over on Human Genesis, where I concluded, "Just a few days ago, someone asked me what I could say about the created kinds of apes.  I had to tell them that I didn’t have much to say at all."  Why not?  What is the evidence for ape kinds?  It's actually pretty sparse.

Before we begin, let's look at the proposed phylogeny of great apes so we can acquaint ourselves with the "layout" of the taxa in question.  This phylogeny is a composite and an approximation based on several different phylogenies that I consulted:


One thing to specially note is the complexity of the "relationships" among the hominins after the split from the lineages leading to chimpanzees (Pan).  Technically, Australopithecus tends to come out as a paraphyletic group, and there have been suggestions that the entire taxonomy of the hominins needs to be reworked.  Solutions to this problem have not really caught on though.  Some propose we put everything in genus Pan, making humans the so-called "third chimpanzee."  Others recommend placing all hominins in genus Homo and making Australopithecus, Paranthropus, Ardipithecus, and others subgenera.  All of these considerations are complicated by the messy nature of fossil-based phylogenies and ongoing criticisms of even the notion of a bifurcating phylogeny at this resolution.  Lee Berger, for example, continues to advocate a "braided stream" analogy for hominin phylogeny (particularly within genus Homo).  Even though I continue to refer to the most popular names (Australopithecus and so forth), I do so with the recognition that things can and do change.

More interesting for us creationists is the fact that "apes" here, meaning everything on this tree from Pongo to Paranthropus, are not monophyletic, i.e., they are not the complete set of descendants of a common ancestor.  To make "apes" monophyletic based on this tree, we would have to include genus Homo.  Traditionally in creationism, I think unconsciously we have looked for baramins that do turn out to be monophyletic in phylogenetic analyses, but here things are different.  The "apes" are paraphyletic.

Does that mean that apes are all one kind though?

Beginning with hybridization studies, we don't find much information available.  Hartwig-Scherer's hominid basic type paper from the 1998 Mere Creation volume summarized things like so:
  • Basic Type Hylobatidae (gibbons) based on observations of intergeneric hybridization within the group.
  • Basic Type Ponginae (orangutans) because at the time the two species were considered subspecies of a single species.  Hybrids between the two species are known however (see here).
  • Basic Type Gorillinae (gorillas and chimps) based on comparative ontogeny and the hypothetical possibility of generating a hybrid.  As far as I can tell, we still don't have a documented case of chimp/gorilla hybrid.
  • Basic Type Australopithecinae - includes anamensis, africanus, afarensis, and the species of Paranthropus.  This is all an estimate based on comparative anatomy.  Ardipithecus is treated as an unknown: "Whether Ardipithecus ramidus should indeed be included into the basic type Australopithecus or whether it belongs to a separate basic type has yet to be shown" (p. 222).
  • Basic Type Homininae - human beings
Among the apes then, Hartwig-Scherer recognizes four basic types (monobaramins) on the basis of hybridization or the possibility of hybridization.

To this I would only add a documented hybrid between chimps and bonobos, the two species of Pan (see here).  So as far as hybrids go, we have intergeneric in the gibbons (Hylobatidae), but only intrageneric in Pongo and Pan.  That's pretty slim evidence to put all apes into a single holobaramin.

What about morphology and statistical baraminology studies?  I haven't really looked carefully at gibbons or orangutans or even gorillas.  Typically, apes are included only as outgroups in studies of genus Homo, and I'm not really surprised that I haven't gotten very good results for those groups.  Here's what I found:
  • In my original 2010 hominin baraminology paper, I argued that Australopithecus should be divided into at least three groups: ParanthropusA. africanus, and "Gorillinae" (A. afarensis, A. garhi, Pan, and Gorilla).  I didn't include other australopiths or other genera in that original paper, so I was uncertain about their relationships.
  • In my 2016 Homo naledi paper, I didn't comment on the relationships of apes, but my results support placing A. africanus into the larger group with gorillas and chimps.  Paranthropus continued to cluster separately.
  • In my 2017 paper, I found once again a cluster of Paranthropus that was separate from other ape taxa and from humans, but I did not find that A. africanus clustered with either chimps and gorillas or A. afarensis.  Likewise with A. afarensis: it was not clustered with chimps and gorillas either.  Chimps and gorillas, however, were clustered together.
So that's my work on the subject, and it's not a unified, consistent picture.  One paper puts A. africanus into a group with A. afarensis and extant chimps and gorillas.  Two papers leave A. africanus out of that group, and one paper separates A. afarensis from the chimp/gorilla group.  If I had to draw a conclusion (which I'm hesitant to do), I would say the evidence currently favors putting chimps and gorillas into one group and that it's possible (not necessarily probable) that A. africanus and A. afarensis belong to that group as well.  All of my studies favor separating Paranthropus into a completely separate group from Homo and all other apes.  I'm really interested in further analyses of these taxa, and I hope to be able to do that in the future, especially as information from Little Foot becomes available.

What about other creationist assessments?  I haven't carefully tracked all the creationist literature over the last few years (as I've been working hard to develop Core Academy), but I can note a few things from the literature that I have seen:
  • Jeanson's 2015 mitochondrial DNA paper appears to begin with the provisional assumption that the family approximates the created kind, and hence he treats gorillas, chimpanzees, and orangutans as a single kind.  That's not the same as arguing that they belong to the same kind, but that wasn't the paper's purpose.
  • Lightner's 2012 Mammalian Ark Kinds paper treats the subject very briefly: "Wilson and Reeder (2005) place the great apes in Hominidae with humans, but given the significant differences between us and apes compared to some of the differences between other families, this seems ludicrous. Therefore, the older designation Pongidae is used here. There are three genera and six species in this family, which includes the gorilla, chimpanzee, and orangutan. Hybrids have been documented between the two species of orangutans (Gray 1972)."  She does distinguish Pongidae from the gibbons (Hylobatidae).  She also stated that "fossil data will only be addressed to a limited degree in this paper," so it's not surprising that australopiths sensu lato are not included in her summary.  Again, her paper was not intended to be an exhaustive treatment of ape kinds but a survey of probable kinds on the Ark.
  • In their 2019 gene content paper [PDF], Lightner and Cserhati put Sumatran orangutans, gorillas, chimpanzees, and bonobos in the same cluster, which they tentatively suggest might also cluster with monkeys.  They're quite skeptical of their own result and very hesitantly suggest that monkeys and great apes (but not humans) belong to a single created kind.  They don't make any firm conclusions on this point, but I suppose their results do support putting Gorilla, Pan, and Pongo in the same created kind.
I'm sure if I've missed something, attentive readers will alert me to my omission, but I think this sample serves to illustrate my point that creationists have not nearly expressed unity on the created kind(s) of apes.  The hybridization data is sparse and only puts together species within a genus.  Hartwig-Scherer is consequently cautious in identifying her basic types.  My morphological results aren't focused specifically on australopiths or extant apes, but I do find limited support for putting A. afarensis, A. africanus, and extant chimps and gorillas in the same group.  Since I haven't included orangutans in my analyses, I can't say anything about them.  I'm fairly skeptical of these results, since the extant apes are included only as an outgroup, and outgroups tend to produce weird results in other studies.  I'm more confident about separating out Paranthropus, which Hartwig-Scherer puts in her Gorillinae basic type, based on very consistent results in all of my analyses.  It would seem that Lightner and Cserhati support at minimum placing orangutans, gorillas, and chimpanzees into the same created kind.  So there does seem to be some consistency to these assessments, but there is a lot of room for improvement.  The conclusions are consistently presented as tentative and provisional.



What of the creationist tendency to place gorillas and chimpanzees (and presumably bonobos) together into a single created kind?  Is that based on good data or just wishful thinking?  Hartwig-Scherer argued for it based on comparative ontogeny.  My results cluster them together as outgroup taxa, and I'm not sure that's a good reason to put them together (it might be).  Lightner and Cserhati say they belong together with orangutans based on their gene content analysis.  So even at this point where most of us agree, I think the data is actually somewhat sparse.  I would be more comfortable with a more concentrated and extensive focus on the apes themselves rather than on the apes as outgroups from human beings.

None of this addresses fossils like Kenyanthropus, Sahelanthropus, Orrorin, or any of the Miocene hominoids.  Some of these fossils have been addressed in papers that mostly evaluate whether they're ancestors of humans rather than being a systematic assessment of their baraminic affinities.  I suspect that focusing on the Miocene forms in particular might tell us a lot about ape baramins that could substantially modify our present assessments.  Who knows?

In any case, I wouldn't be remotely comfortable with the overgeneralized conclusion that there is a single ape kind descended from an ancestral pair on the Ark that includes australopiths, gorillas, orangutans, and chimpanzees.  I think that's very liable to change in the future, possibly even the near future, and I think therefore we ought to show more caution where the data is more tentative.

Now that I think about it, playing around with Miocene ape baraminology sounds like a fun afternoon diversion. If you'll excuse me ...

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