Todd Wood's Take on Danuvius

Todd Wood is always interesting to read, even if I don't share his chronological leanings.  He has thoughts on the new Miocene ape from Bavaria, Danuvius:

Based on the fragmentary remains, we make some really interesting observations about the anatomy of Danuvius. These apes had strongly opposed big toes, which would allow them to effectively grip things with their feet. Their tibiae (shinbones) have the kinds of joints that would allow them to walk upright, and their femora (thighbones) support that conclusion. These apes might have been in some way bipedal. The arm bones they found have traits that are associated with suspensory locomotion, like hanging from tree branches. The body size was fairly small, about the mass of a bonobo.

As I mentioned in my post, I think the evidence for bipedalism is vastly over-stated and, even if it can be shown that this “Extended Limb Clambering” is shared by other fossil ape finds from the region, there is no particular reason to think that these critters were ancestral to later hominins. It is entirely likely that they exhibited a separate adaptation to this particular style of locomotion.  Todd raises some other questions, though, that are not answered in the paper:

So why not address similarities of Danuvius to later fossil hominins? The authors are trying to establish a new means of locomotion that they call Extended Limb Clambering (ELC). So they compare Danuvius to living primates (where the authors know how they get around), and they're interested in comparing it to contemporary Miocene apes of Europe. But they're not all that excited about other comparisons to later fossil forms like Ardipithecus, Australopithecus, or Orrorin. They also don't relate their findings to later fossil apes in Europe like Graecopithecus or the Trachilos tracks, both of which have been linked to hominins or bipedality. Perhaps they don't think those things are worth talking about (maybe because they're skeptical of Graecopithecus like I am), but I guess I just don't agree.

I think that part of the reason that these questions are not raised is because there is so much of a gap between these finds, chronologically and geographically. There is simply with which to relate them. As Todd points out, the hominin status of Graecopithecus is dubious, at best, and, even if the Trachilos tracks are hominin, they are still quite a distance from Bavaria and six million years later in time.

For now, this fossil ape stands on its own.  If we find other evidence of incipient bipedality in other forms in the area and can relate them to later forms, then the picture might change.  For now, though, Danuvius is a very interesting, odd Miocene ape. 

More Evidence For Bipedality at 4.5 MYA

Out of Case Western Reserve comes a study of some new fossil material that sheds like on early human bipedal adaptation.  From ScienceDaily:

Scott W. Simpson, PhD, led an analysis of a 4.5 million-year-old fragmentary female skeleton of the human ancestor Ardipithecus ramidus that was discovered in the Gona Project study area in the Afar Regional State of Ethiopia.

The newly analyzed fossils document a greater, but far from perfect, adaptation to bipedalism in the Ar. ramidus ankle and hallux (big toe) than previously recognized. "Our research shows that while Ardipithecus was a lousy biped, she was somewhat better than we thought before," said Simpson.

While the weight of evidence has always a bit more than slightly favored the facultative bipedality of Ardipithecus ramidus, this research provides greater support for this hypothesis.  In my class, I stress the difference between facultative bipedality (practiced by Ardipithecus) and obligate bipedality (practiced by every other hominin).  Additionally, from the article¹:

The more complete adoption of bipedality in the australopiths resulted in the loss of functionally critical adaptations to arboreality present in Ardipithecus such as a grasping, opposable hallux, an antero-posteriorly broad pelvis with reorganization of the origin (and most likely function) of the hamstring muscles, and a more derived humero-femoral ratio. The changes in the size and structure of the dentition in the subsequent australopiths (larger molar and premolar crowns, increased enamel thickness, more robust mandibles) indicates a major behavioral and dietary shift for most hominins (perhaps excluding the species indicated by the Burtele foot) that occurred about 4.2 Ma with the earliest appearance of Australopithecus (Leakey et al., 1995, White et al., 2006).

Many of these changes, then, appear to have occurred somewhat rapidly, once the early hominins moved away from the forest and into the fringe.  Once we thought that bipedality originated in the forest/fringe.  The Ardipithecus data have killed this hypothesis. 


¹Scott W. Simpson, Naomi E. Levin, Jay Quade, Michael J. Rogers, Sileshi Semaw. Ardipithecus ramidus postcrania from the Gona Project area, Afar Regional State, Ethiopia. Journal of Human Evolution, 2019; 129: 1 DOI: 10.1016/j.jhevol.2018.12.005

Mutation Rate in Humans Has Slowed Down

I am not quite sure what this means, yet. Researchers at the Aarhus University, Denmark, and the Copenhagen Zoo have discovered that, when compared to our nearest taxonomic relatives, our mutation rates have slowed down. Science Daily has the scoop:

"Over the past six years, several large studies have done this for humans, so we have extensive knowledge about the number of new mutations that occur in humans every year. Until now, however, there have not been any good estimates of mutation rates in our closest primate relatives," says Søren Besenbacher from Aarhus University.

The study has looked at ten families with father, mother and offspring: seven chimpanzee-families, two gorilla families and one orangutan family. In all the families, researchers found more mutations than would be expected on the basis of the number of mutations that would typically arise in human families with parents of similar age. This means that the annual mutation rate is now about one-third lower in humans than in apes.

Why is this important for the study of human origins?

The higher rates in apes have an impact on the length of time estimated to have passed since the common ancestor of humans and chimpanzees lived. This is because a higher mutation rate means that the number of genetic differences between humans and chimpanzees will accumulate over a shorter period.

If the new mutation rates for apes are applied, the researchers estimate that the species formation (speciation) that separated humans from chimpanzees took place around 6.6 million years ago. If the mutation rate for humans is applied, speciation should have been around 10 million years ago.

The six-to-eight million year point for the LCA never made a whole lot of sense to me. If the fossil material from Orrorin, at 6 mya really does reflect bipedality, then the split has to have been much earlier.  The material from Ardipithecus kadabba is very sketchy with regard to bipedalism (one toe bone found ten miles away), but the fragmentary post-cranial bones can be confidently identified as being hominin, in nature.  Furthermore, the fossil material is dated to between 5.6 and 5.8 mya.  That would leave a very short period of time.  It cannot be pre-split because the fossil material exhibits derivations in the hominin direction, rather than the modern ape direction. 

If this study holds up, it will change how we view the search for the LCA. 

New Laetoli Footprints Demonstrate Full Bipedality

A story running in Newsweek and the Washington Post (and other outlets, presumably), details research into the newly discovered fossil footprints at Laetoli dated to 3.6 mya that clearly show a modern human gait.

Two sites in Laetoli, Tanzania, feature footprints of human ancestors who lived about 3.6 million years ago. They were members of the genus Australopithecus. That's the genus of “Lucy,” the 3.2 million-year-old human ancestor whose fossilized bones were discovered in Ethiopia in 1974.

David Raichlen, an evolutionary anthropologist at the University of Arizona, has studied the Laetoli footprints and compared them to footprints made by human volunteers in laboratory settings. He examined footprints of individuals walking normally and also those walking with bent knees and bent hips. (Scientists who study locomotion use the acronym BKBH). The Laetoli footprints more closely match modern human footprints.

“Upright, humanlike bipedal walking goes back 4 to 5 million years,” Raichlen told The Washington Post in advance of a symposium on the evolution of human locomotion, which took place Sunday at the Experimental Biology 2018 conference in San Diego.

This dovetails with the recent findings that Ardipithecus, a hominin dated to around 4.4 mya, likely could travel equally well on the ground or in the trees.  Oddly, the WaPo article doesn't mention this.  

Ardipithecus May Not Have Been Entirely a Facultative Biped After All

In a new article in the Proceedings of the National Academy of Sciences, several researchers have concluded, using 3D morphometric analysis have discovered that Ardipithecus ramidus, while still having facultative (didn't have to but could) bipedalism, when it did walk, its bipedal gait was nearly human.  From the abstract:

We show that hamstring-powered hip extension during habitual walking and climbing in living apes and humans is strongly predicted, and likely constrained, by the relative length and orientation of the ischium. Ape pelves permit greater extensor moments at the hip, enhancing climbing capability, but limit their range of hip extension, resulting in a crouched gait. Human pelves reduce hip extensor moments but permit a greater degree of hip extension, which greatly improves walking economy (i.e., distance traveled/energy consumed). Applying these results to fossil pelves suggests that early hominins differed from both humans and extant apes in having an economical walking gait without sacrificing climbing capability. Ardipithecus was capable of nearly human-like hip extension during bipedal walking, but retained the capacity for powerful, ape-like hip extension during vertical climbing. Hip extension capability was essentially human-like in Australopithecus afarensis and Australopithecus africanus, suggesting an economical walking gait but reduced mechanical advantage for powered hip extension during climbing.

This positions Ardipithecus as the classic intermediate in terms of bipedal locomotion.Although there are many traits in Australopithecus afarensis that are still transitional in terms of the rib cage, dentition and aspects of the hip, it is clear that the major adaptations for bipedalism were in place nearly a million years earlier.  This also suggests that it is not out of the realm of possibility that the fossil footprints in Crete really do reflect a bipedal hominin.  At the risk of positing heresy, the fact remains that we really don't know exactly where hominins first appeared.  This study also reinforced the distinct separation between apes and humans in terms of iliac shape, and that this split must have taken place even further back in time that we have supposed.

The Independent has a news story on this here.  One of the authors, Herman Pontzer remarks:

“It kicks us out of this old paradigm of thinking about human evolution,”...“In that old picture that is everywhere where you have the evolution of man going from crouching thing to upright thing to a human – as much as we have known that is not right, I still think people have it in their heads.”

5.7 Million Year-Old Human Footprints Found on Greek Island of Crete

Great Googlymoogly!  This one is lighting up all over the Internet.  Fossil footprints have been found in the southern Greek Island of Crete, near the village of Trachilos, that appear to have the distinctive heel-toe-off gait of bipedal humans.  The catch? The prints are 5.7 million years old!  From PhysOrg:

Human feet have a very distinctive shape, different from all other land animals. The combination of a long sole, five short forward-pointing toes without claws, and a hallux ("big toe") that is larger than the other toes, is unique. The feet of our closest relatives, the great apes, look more like a human hand with a thumb-like hallux that sticks out to the side. The Laetoli footprints, thought to have been made by Australopithecus, are quite similar to those of modern humans except that the heel is narrower and the sole lacks a proper arch. By contrast, the 4.4 million year old Ardipithecus ramidus from Ethiopia, the oldest hominin known from reasonably complete fossils, has an ape-like foot. The researchers who described Ardipithecus argued that it is a direct ancestor of later hominins, implying that a human-like foot had not yet evolved at that time.

The new footprints, from Trachilos in western Crete, have an unmistakably human-like form. This is especially true of the toes. The big toe is similar to our own in shape, size and position; it is also associated with a distinct 'ball' on the sole, which is never present in apes. The sole of the foot is proportionately shorter than in the Laetoli prints, but it has the same general form. In short, the shape of the Trachilos prints indicates unambiguously that they belong to an early hominin, somewhat more primitive than the Laetoli trackmaker. They were made on a sandy seashore, possibly a small river delta, whereas the Laetoli tracks were made in volcanic ash.

And now, the other shoe.  How do we know how old the fossil footprints are?  

The coastal rocks at Trachilos, west of Kissamos Harbour in western Crete (Fig. 1a–c), lie within the Platanos Basin, and present a succession of shallow marine late Miocene carbonates and siliciclastics of the Roka Formation, a local development of the Vrysses Group (Freudenthal, 1969 ; van Hinsbergen and Meulenkamp, 2006; Figs. 1d, e and 3a, b). At the top, this marine succession terminates abruptly in the coarse-grained terrigenous sedimentary rocks of the Hellenikon Group (Figs. 1d and 3e, f), which formed by the desiccation of the Mediterranean Basin during the Messinian Salinity Crisis (van Hinsbergen and Meulenkamp, 2006), an event dated to approximately 5.6 Ma (Govers, 2009). The succession (Fig. 1d) contains an emergent horizon with well-preserved terrestrial trace fossils and microbially induced sedimentary structures (Fig. 3d) immediately overlying shallow water ripplemark structures (Fig. 3c).¹

So, the authors are a tad more circumspect than the writers of the PhysOrg story.  The authors posit two hypotheses for their results: 1. the tracks represent the gait of a basal hominin, which explains the non-divergence and shape of the big toe as well as the shape of the ends of the other toes, which resemble those of a human foot and not a non-human foot.  This fits approximately with the dates of the north African remains of Orrorin and, perhaps, that of Sahelanthropus (although that is pretty much a surface find).

The Messinian Crisis was a period of time during the Miocene epoch during which the Mediterranean Sea almost completely dried up.  This crisis began around 6 million years ago and ended around 5.3 million years ago with what is known as the Zanclean flood.  It is estimated that once the barrier at the Strait of Gibraltar was broken, the Mediterranean Sea refilled within two years, which means that the sea level rose at an estimated 30 feet per day.

Okay...now, lets go back here, to the story that came out about four months ago, establishing the possibility that the last common ancestor to apes and humans was in Europe.  In that study, a jaw with human root patterns and an isolated premolar that have both been attributed to Graecopithecus, were re-examined and found by the researchers to have hominin affinities, a surprising conclusion, given their age of 7.15 million years.  At the time that story appeared, I remarked that it was a bit of a stretch to hang one's hat on one premolar and partial ape-like mandible, but in the context of the new finds, maybe not so much.  This strengthens the (admittedly far-fetched) notion that our ancestors did, in fact, originate somewhere in southeast Mediterranean Europe and, over the course of the next two and half million years ago, migrated south to north Africa.

As Per Ahlberg was quoted as saying:

"This discovery challenges the established narrative of early human evolution head-on and is likely to generate a lot of debate. Whether the human origins research community will accept fossil footprints as conclusive evidence of the presence of hominins in the Miocene of Crete remains to be seen."

This is huge news.  Even if we can't place the LCA in southern Europe, we now have bipedalism extending back into the late Miocene. 


¹Gerard D. Gierliński et al, Possible hominin footprints from the late Miocene (c. 5.7 Ma) of Crete?, Proceedings of the Geologists' Association (2017). DOI: 10.1016/j.pgeola.2017.07.006

Was the LCA in Europe????

Was the last common ancestor of apes and humans in Europe?  That seems to be the gist of a study published in the PLoS One.  Nicole Mortillaro, of CBC News reports:

A jawbone discovered by German troops in Athens during the Second World War could be evidence that apes and humans diverged 200,000 years earlier than the current theory says.

Chimpanzees and bonobos are the nearest known relatives to humans, sharing 99 per cent of our DNA. It's believed that we split between five and seven million years ago.

However, researchers analyzing two fossils — a jawbone from a German museum and an upper premolar from a collection in Bulgaria — concluded their ages to be roughly 7.2 million years, and belonging to a pre-human.

From the paper in PLoS:

The split of our own clade from the Panini is undocumented in the fossil record. To fill this gap we investigated the dentognathic morphology of Graecopithecus freybergi from Pyrgos Vassilissis (Greece) and cf. Graecopithecus sp. from Azmaka (Bulgaria), using new μCT and 3D reconstructions of the two known specimens. Pyrgos Vassilissis and Azmaka are currently dated to the early Messinian at 7.175 Ma and 7.24 Ma. Mainly based on its external preservation and the previously vague dating, Graecopithecus is often referred to as nomen dubium. The examination of its previously unknown dental root and pulp canal morphology confirms the taxonomic distinction from the significantly older northern Greek hominine Ouranopithecus. Furthermore, it shows features that point to a possible phylogenetic affinity with hominins. G. freybergi uniquely shares p4 partial root fusion and a possible canine root reduction with this tribe and therefore, provides intriguing evidence of what could be the oldest known hominin.

Hominin, in this case, means humans and their premodern forms.  I think it is more than somewhat suspect to base a far-reaching hypothesis on one trait, even if it is the p⁴ root. It is commonly held that the last common ancestor of apes and humans was in Africa, sometime around 7.5 to 8 million years ago, but we have no fossil evidence to support that position.  While it is certainly true that the further back in time you go, the more ape-like our ancestors get, there is simply no smoking gun.

The world will not end if the LCA is, in fact, in southern Europe, but if it is, then it raises some interesting questions.  For one, if the LCA is in Europe, why are all of its hominin descendants in Africa?  So far, even discounting Sahelanthropus, which is a surface find and was crushed, all of the late Miocene and early Pliocene hominin remains are found in either the Afar triangle (Ardipithecus) or the Tugen Hills, in Kenya (Orrorin tugenensis).  If you add Sahelanthropus, then Chad comes into the picture. Additionally, why have we found no post-split hominids in southern Europe?  So far, all that has come out of the ground in this region is middle to late Miocene apes.

Other hurdles exist to acceptance of this idea.  For one, it is pretty clear that our closest living relatives, genetically, are the chimpanzees, who reside in the tropics of central Africa.   Next on the list is the gorilla, also found in the tropics of Africa.  Why have we found no precursors to these hominoids in southern Europe? 

On the other hand, the fossil find has been securely dated to the Messinian Event, in which the Mediterranean Sea effectively dried up, suggesting the possibility that the ancestors of the Pliocene hominins from North Africa migrated from southern Greece.  If this is so, then it raises the dark and ominous thought that much of the information regarding the LCA lies at the bottom of the Mediterranean Sea. That is terrible to contemplate.  This would also mean that Chimpanzees and Gorillas are the survivors of a group of Miocene apes that ranged from southern Europe to central Africa.  We know that the ancestors of chimpanzees once upon a time occupied the East African Rift Valley, but are now restricted to central and west Africa.   If their original range extended up into Egypt and beyond, then perhaps we are looking at a similar situation for their ancestors, as well.  

A whole lot more investigation needs to be done and more fossil remains need to be found to shore up the European LCA hypothesis.  Given that this new information does not come from newly discovered fossils does not raise my hopes. 

Humans and Fire

It had been conventional wisdom that the origin of bipedality occurred in a forest/fringe environment and that a move to the savannah during the dry-out at the end of the Pliocene accelerated the evolution of humans.  That was thrown into turmoil when it was discovered that Ardipithecus ramidus possessed facultative bipedal characteristics at 4.4 million years but lived in an entirely forested environment.

Now, it seems, the savannah is seen as playing a different role in human evolution.  Charles Q. Choi, of Scientific American writes:

A longtime theory holds that early humans discovered how to use fire accidentally—perhaps while making stone tools they found that striking rocks against each other could generate sparks, and then gradually learned fire had many uses.

The problem with such serendipity-based explanations is that they "raise more questions than they answer," says evolutionary anthropologist Christopher Parker at the University of Utah in Salt Lake City. For example, these theories do not address when or where the discovery might have occurred, why it did not happen earlier or why other animals that use stone tools—chimpanzees, capuchin monkeys, crab-eating macaques and sea otters are known to do so—did not also develop fire use, Parker notes.

Parker and his colleagues suggest in a study published in the April Evolutionary Anthropology that humans developed fire use as a natural response to environmental changes. Previous research found that roughly 3.6 million to 1.4 million years ago—as the genus Homo emerged in Africa—the continent regularly experienced bouts of aridity, causing forests to shrink and dry grasslands to spread. Earlier studies suggested these climate shifts may have driven humanity’s ancestors away from a life climbing trees and toward one of walking upright on the ground, Parker says.

Yes, but there have been, as alluded to above, issues with these previous studies. If bipedality originated in the forest, as a response to who-knows-what, then they already possessed it when the drying out began. But this is not the crux of Parker's research:

Parker and his colleagues suggest in the new study that our ancestors not only grew accustomed to fire but learned to exploit it as a naturally occurring resource. This adaptation, called pyrophilia, may have set the stage for more active and deliberate human use of fire.

The research team's models suggest early humans benefited from wildfires in a number of ways: The blazes would have made it easier to find food, much as Martu Aboriginal women in Australia still rely on fire to clear brush for more efficient hunting. The models also indicate that early humans might have combed the charred remains of wildfires to dine on animals, seeds, nuts and tubers cooked in the flames—benefitting from a chemical process that not only makes many foods easier to digest but kills germs and neutralizes some toxins.

This has not been proposed before and it will be interesting to see if more evidence of this is found. Read the whole thing.

Human/Gorilla Split at Eight MYA?

Scientific American is running an article, which details work by Gen Suwa and colleagues, in the Afar Triangle, where nine gorilla-sized teeth were found in 2007 that have now been securely dated to around eight million years ago.  The researchers named the species Chororopithecus abyssinicus.  Charles Choi writes: 

The age and location of these fossils strengthen the view that the human and the modern ape lines originated in Africa and not Asia, the researchers said.

"Until now, no mammalian fossils south of the Sahara have been securely dated to 8 million to 9 million years ago," Suwa said. "Any and all fossils from this crucial time period of Africa would help unravel the story of human origins and emergence. These are the first such fossils."

In addition, until recently, "most scientists, especially geneticists, thought that the human-chimp split was as recent as 5 million years ago, and that the human-gorilla split was only about 7 million to 8 million years ago," Suwa said. "This contradicted the fossil record. For example, fossils thought to be on the human side of the split such as Ardipithecus kadabba from Ethiopia and Sahelanthropus from Chad were 6 million years old — or, in the case of the Chad fossil, perhaps 7 million years old."

The new findings suggest that Chororapithecus is 8 million years old, so "the actual gorilla-human split must then have been up to several million years before that," Suwa said.

More pieces to the puzzle. The other mystery, of course, is when the last common ancestor of humans and chimpanzees lived.

Casey Luskin on Homo naledi

Casey Luskin has written a piece for Evolution, News and Views, in which he examines the hype surrounding the new Homo naledi find.  It would take more time than I have to tackle it point by point, but I will hit the high notes.  He writes:

It has long been recognized that we are missing fossils documenting the supposed transition from the apelike genus Australopithecus to the humanlike Homo. Despite what you may be hearing in the media, Homo naledi does not solve this problem.

That's okay. It wasn't meant to. It fills in a bit of a puzzle, that is all. We now have more information than we had about this transition, which appears to have been complex.  He continues:

Some have envisioned the hallowed intermediate link being a creature with an apelike body and a human-like head. For some time, Homo habilis was claimed to be such a candidate -- until cooler heads prevailed, as I noted earlier. Others have hoped we'd uncover something with a more Homo-like postcranial (below the head) skeleton but a more australopith-ape-like body. Indeed, almost exactly four years ago, in a post titled "Hominid Hype and the Election Cycle," I noted these precise arguments with regard to Australopithecus sediba.

Coincidently, we're right now in almost exactly the same place in the election cycle, and seeing almost identical claims about this new fossil discovery. Indeed, Homo naledi was discovered (and is being promoted) by the same researcher, Lee Berger, that unveiled (and promoted) sediba, although, as we'll see, naledi has a very different and unique set of traits from sediba.

One of the issues so far has been the dating of the remains.  Luskin, in quoting Carol Ward's concerns about lack of dating of the fossils, makes a legitimate objection in that we do not know how old the bones are.  That is a problem.  As I pointed out in my BioLogos post, we can date the cave floor, we can date the cave walls and we can date the cave ceiling but we have little to no idea when the bones were dropped in.  It is clear that the floor of this cave was not a living floor.  He writes:

The main claim about Homo naledi is that it is a small-brained hominin (when compared to humans) that has other features that are very humanlike -- especially its hands and feet. As the news headlines suggest, there has been an immense amount of hype about this species, consistent with the hype surrounding Australopithecus sediba, which again was discovered and promoted by the same researcher, Lee Berger. However, while there are some humanlike aspects of its body plan, my overall impression is that this is a highly unique species that doesn't fit well into previously established categories.

He is also correct about that.  It doesn't.  H. naledi has characteristics that link it with many different hominins and the combination of traits is unique.   This is not a problem it is, as Carol Ward commented, shows us that there was considerable hominin diversity at this time and, apparently at other times in the past.  The problem is that he uses selective passages and slanted wording to imply that the case for it having "human" traits is overblown.  For example:

  For example, Luskin writes:

The hands are claimed to be humanlike but they have key unique features and, unlike human hands, are tailored for climbing. ABC News reported: "Homo naledi had human-like hands and feet, but Tattersall said it was impressive that it also had climbing features, more similar to an ape." CNN reports: "Its hands are superficially humanlike, but the finger bones are locked into a curve -- a trait that suggests climbing and tool-using capabilities." And even Berger states: "It's pretty clear from those fingers that they're [for] climbing."

All of this is done to shift the emphasis away from the fact that, while the hominin did possess primitive traits, it also possessed derived ones. Let's see what Berger actually writes about the find:

The hand shares many derived features of modern humans and Neandertals in the thumb, wrist, and palm, but has relatively long and markedly curved fingers (Kivell et al., 2015). The thumb is long relative to the length of the other digits, and includes a robust metacarpal with well-developed intrinsic (M. opponens pollicis and M. first dorsal interosseous) muscle attachments.

Note the characteristics that Luskin leaves out.  With regard to our understanding of its taxonomic designation, Luskin writes:

Even Berger admits, "It doesn't look a lot like us." He also states: "There may be debate over the Homo designation" since "the species is quite different from anything else we have seen."

It wouldn't be surprising if later analyses change our understanding of the fossil.

He then puts in the following quote from an interview of Carol Ward in The Scientist:

Carol Ward, a professor of pathology and anatomical sciences at the University of Missouri who was not involved with the study said she was disappointed by the lack of empirical data presented in the paper. "There are only tiny composite pictures of the fossils, so you can't see them and there are no comparative data comparing it to anything else," said Ward. "There's nothing we can use to make our own judgments about the validity of what they are saying."

The problem is that he leaves out a rather significant statement about the find that precedes that. Here is the entire passage from the article (emphasis added):

“H. naledi possesses a combination of primitive and derived features not seen in the hand of any other hominin,” the authors wrote, but Carol Ward, a professor of pathology and anatomical sciences at the University of Missouri who was not involved with the study said she was disappointed by the lack of empirical data presented in the paper. “There are only tiny composite pictures of the fossils, so you can’t see them and there are no comparative data comparing it to anything else,” said Ward. “There’s nothing we can use to make our own judgments about the validity of what they are saying.”

Luskin has done two things here.  By removing the ellipses in from of the initial part of the quote, he suggests that this is a self-contained thought, which it clearly is not.  Further, by not quoting the initial statement of Ward's, he omits that she sees not just primitive but derived traits as well.  This is a pattern throughout his piece.

He phrases the rest of the piece in the form of four controversies.

The first is “How Old is Homo naledi?”  The irony here is that Luskin could very easily have focused on this topic and left it at that.  He has Berger over a barrel, here.  We don't know how old the bones are.  We have zero idea when they were dropped in. Gunter Brauer had a problem in the 1990s with an important skull in the transition to early modern humans, Eliye Springs, which washed out a bank where the spring entered Lake Turkana.  Great find, no idea what its age is.  As I mentioned in my blog post on Homo naledi, the South African cave sites present a serious problem for dating the hominins in which they are found.  Some success has been had but many finds are simply given wide chronological ranges.

Consequently, if Homo naledi is between 2 and 3 mya, it represents a find that is near where the transition is thought to occur, based on the presence of early Homo in East Africa, although the Ledi jaw may suggest an earlier transition.  On the other hand, if it is late, say 1 mya, then it simply represents a dead end that retained many primitive traits.

Here is what Luskin writes about this:

But some of naledi's advocates think they know what to make of the fossils, despite the compete current lack of an age for these fossils. How do they know? Evolutionary assumptions, which drive a desire among some that the bones should turn out to be somewhere between 2.5 and 3 million years old.

This is not entirely true and Luskin knows it, or ought to. There are perfectly valid reasons to suggest that this find is this old, even if we do not, in fact, know its age. For one thing, we know that we have hominins in East Africa that have derived traits toward modern humans between 2.3 and 1.8 million years ago.  Consequently, we know that the transition to this form(s) took place somewhere between 2.5 and 3.0 million years ago.  Further, this tracks with the discovery of the Ledi jaw, which has a mix of australopithecine and early Homo traits and is dated to 2.8 mya.  Therefore, do we know how old the Homo naledi fossils are?  No, we don't.  Are the estimated dates just being driven by evolutionary assumptions?  Clearly not.

Controversy Number 2: “Is Homo naledi a single species?”  Luskin writes:

The question of whether the bones currently assigned to Homo naledi represent a single species may seem like an academic one but it actually could bear directly upon whether it's something like a transitional form, or nothing of the kind. Jeffrey Schwartz, an anthropologist at the University of Pittsburgh, thinks the bones represent multiple species because of the two different types of skulls found in the cave.

Where Luskin is going with this is that, if there are, in fact, two different species in the cave, then some of them might just be modern human.  He continues:

The fact that Berger appeals to sexual dimorphism (different morphologies between males and females of a single species) to explain the different skulls is revealing. It shows that there is indeed a challenge to his "single species" claim. However, if there are multiple species, then you don't necessarily know that humanlike hands and feet didn't come from something more like us, whereas the small heads came from another species more like an australopith. We just don't know.

Here, he glosses over something very important:  even the human-like skeletal material has characteristics that are not modern for example:

• The small heads have both angular and occipital tori, characteristics only found on Homo erectus.  No australopithecine has these and no modern human does, either.
• The faces, while being small, lack australopithecine traits such as canine jugae and anterior pillars.  Further, there is limited post-orbital constriction, a more modern characteristic.
• Even the “human-like” hands and feet have characteristics that are primitive. For example, Berger writes: 

  The talar head and neck exhibit strong, humanlike torsion; the horizontal angle is higher than in most humans, similar to that found in australopiths. The calcaneus is only moderately robust, but possesses the plantar declination of the retrotrochlear eminence and plantarly positioned lateral plantar process found in both modern humans and Au. afarensis...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...Overall, carpal shapes and articular configurations are very similar to those of modern humans and Neandertals, and unlike those of great apes and other extinct hominins. However, the H. naledi wrist lacks a third metacarpal styloid process, has a more radioulnarly oriented capitate-Mc2 joint, and has a relatively small trapezium-Mc1 joint compared to humans and Neandertals. Moreover, the phalanges are long (relative to the palm) and more curved than most australopiths.

Therefore, appeals to there being modern humans in the cave along with australopithecines are not warranted. Maybe there was more than one species in the cave and one of them was an australopithecine. What remained, however, was not modern human.  There are no modern humans walking around with angular and occipital tori.

But say there is more than one species down there, and these different species represent different times in the history of hominin evolution.  Would this be a bad thing? What it would mean is that there is a good deal of variability in the human fossil record, something we already suspected anyway.  We know that expanded diversity existed as far back as Ardipithecus.  Why would it not be present at other times?

Controversy No. 3: Did Homo naledi Bury Its Dead?  Here is Luskin:

A major claim being promoted in the media holds that Homo naledi ritualistically buried its dead, a testimony to its supposedly human-like intellect.

and

Even if this story is true, it's not the case that this species buried its dead in any manner like humans bury their dead. The bones weren't buried in the ground. Rather, it seems like the bodies were just tossed into the back crevice of a cave and left there to rot...

Luskin is correct that the media attention to this is overblown and sensationalistic. Luskin goes on, then to quote many different researchers who are skeptical about this claim (skepticism that I think is warranted, by the way) But let's see what Berger et al. say about it. First, the word “burial” never appears once in the original paper by Berger et al. That information comes from the supplementary paper by Dirks et al., who write this:

The Dinaledi collection displays taphonomic characteristics indicative of a depositional history that involved several stages of burial with surface modifications and breakage patterns consistent with repeated reworking of at least part of the assemblage within the confines of the Dinaledi Chamber, involving both biotic and abiotic agents (Supplementary file 2). The distribution of bone material and skeletal part representation indicative of limited winnowing (Table 1) indicate that the fossils of H. naledi must have found their way into the chamber via a difficult route that precluded any other large vertebrates from finding a way in. The distribution of the fossils within reworked material derived from Unit 2, as well-articulated remains in Unit 3 suggests that H. naledi fossils entered the chamber over an extended period of time; that is, not all remains were deposited at once.

So that is what we know, and that is all we know.  First, I was wrong in my post on BioLogos, this is not a standard karst cave with a top opening of any kind.  Consequently, there is no way for the bones to have gotten there unless they were placed there.  There is one possible explanation that is not mentioned by Dirks that is not in the account by Luskin:

Flowstone formation continues today (Flowstone 3), changing the morphology of cave passages. This makes it possible that a more direct access-way or easier passage may have existed when hominins entered. A different entrance into the chamber may also explain the presence of rodent bone concentrations in Facies 1b. However, sedimentation patterns indicate that the accumulation of Unit 2 with fossils occurred below the current entry point into the chamber, and alternate routes did not involve vertical access shafts that connected directly to surface in either the Dinaledi Chamber or nearby Dragon's Back Chamber.

This doesn't address the reliability of the burial hypothesis but it does suggest that it might have been much easier for the bones to get where they were.  I suspect that Jungers is correct in his hypothesis about whether or not they were intentionally buried.

Controversy No. 4: Does "Homo" naledi Belong in Homo? Luskin writes:

Ian Tattersall told ABC News: "We're [probably] looking at a cousin rather than an ancestor, but who knows."

"Who knows..." That is exactly right. Even Berger stated: "We need to be very cautious about proclaiming everything we find as the direct ancestors of humans, it's clear there are a lot of experiments going on out there."

Much is left out of this series of statements. Let's go back to the ABC article from which it is quoted:

Researchers said the newly discovered species most resembles other hominids such as Homo erectus, Homo habilis and Homo rudolfensis.

Ian Tattersall, curator emeritus at the American Museum of Natural History in New York, said the find was incredibly important and could shed important light on Homo sapiens, modern humans, as a species and the many other early hominoids.

“It’s really very exciting,” Tattersall told ABC News. “What this is doing is definitely increasing the perception that we have -- that evolution of hominids was one of vigorous experimentation of evolution.”

Why would the find shed any light on Homo if it did not have any characteristics of Homo? As numerous researchers have commented, it absolutely does.  Many of the characteristics that align it with Homo erectus have been pointed out, as well as other deviations from australopithecines.

Much of what Luskin is trying to accomplish in this section is focused on the fact that, while the Dinaledi finds have characteristics that align them with Homo, they also have some that align them with australopithecines and maybe we are over-interpreting the early Homo ones.  He then vaguely supports his case by using a series of quotes from researchers who are skeptical that we know exactly what H. naledi actually is.  For example, he writes this:

Schwartz himself wrote a scathing op-ed in Newsweek, "Why the Homo Naledi Discovery May Not Be Quite What it Seems." He argued that "Homo naledi" may in fact represent multiple species, and probably doesn't belong in Homo:

Interestingly, he then quotes Schwartz, who points out only the australopithecine portions of the anatomy, to the exclusion of any of the modern traits that it has.  While it is quite true that there are differing opinions about what these finds represent, it is equally true that there are Homo traits present.  Consequently, to simply lump them in with australopithecines is inaccurate.  It may be years before we have enough information to make a sound judgment about exactly where this fits in the pantheon of human evolution, but for now, we can safely say that, whether or not there are one species present or two, a hominin with some of the traits of early Homo was present at this cave.

But even if

it turns out that H. naledi is, in fact, Au. naledi, after much reflection.  Then it just means that australopithecine diversity is greater than we thought it was and that there were many different morphs that exhibited a wide range of traits, some of which were derived in the direction of Homo.  That we don't know exactly which form gave rise to an early Homo form is not a deal-breaker.  Remember, systematics does not reveal ancestor-descendant relationships, but, instead, sister taxa.  Au. sediba and H. naledi are two different forms that express a mosaic of traits, some of which are advanced and some which are not.  They are both considerably more advanced than the australopithecines that preceded them.

Luskin is focused on the fact that H. naledi is probably not the missing link between the australopithecines and early Homo that everybody was hoping for.  That is beside the point.  The point is we now know quite a bit more about this stage of human evolution.  Even if the bones turn out to be younger than we thought, it still gives us information about human evolutionary development that we did not already have.  That's okay.

BioLogos, Ken Ham and David Menton—A Response, Part VI: The Conclusion

This concludes my response to David Menton's post on human origins, which has been a chore to read and respond to. Menton's conclusion is so short, I will post it in its entirety:

Why then are there continued efforts to make apes out of man and man out of apes? In one of the most remarkably frank and candid assessments of the whole subject and the methodology of paleoanthropology, Dr. David Pilbeam (a distinguished professor of anthropology) suggested the following:

Perhaps generations of students of human evolution, including myself, have been flailing about in the dark; that our data base is too sparse, too slippery, for it to be able to mold our theories. Rather the theories are more statements about us and ideology than about the past. Paleoanthropology reveals more about how humans view themselves than it does about how humans came about. But that is heresy.

Oh, that these heretical words were printed as a warning on every textbook, magazine, newspaper article, and statue that presumes to deal with the bestial origin of man!
No, we are not descended from apes. Rather, God created man as the crown of His creation on Day 6. We are a special creation of God, made in His image, to bring Him glory. What a revolution this truth would make if our evolutionized culture truly understood it!

First, David Pilbeam wrote that almost forty years ago, and yet Menton appears to hold it up as current scholarship.  You wouldn't do that in any legitimate scientific discipline.  It may be a good example of “look what we thought back then,” in a historical sense and as compare and contrast but not current thought.  This is a typical young earth creationist tactic: find a useful quote and keep using it, long after it is no longer true or has been debunked.  As such, it is no different than using (or abusing) Solly Zuckerman's quote from the early 1970s.  I saw Duane Gish at the University of Tennessee a few years back he used Zuckerman's quote as well.  Once a quote is found, it makes the rounds.

Pilbeam's quote comes from a review of Richard Leakey's book Origins and is found in the American Scientist (Vol. 66, No. 3, May-June 1978).  Let's see what Pilbeam thinks about palaeoanthropology as of 1995:

The discovery of an australopithecine mandible together with a middle Pliocene fauna 2,500 km west of the Rift Valley considerably extends the known range of these early hominids and raises several interesting issues. The Chad specimen is most similar to its East African contemporary A. afarensis. Nevertheless, in certain features-mandibular morphology, premolar roots and enamel thickness- it differs from the described hypodigm of A. afarensis . Given the genetic and morphological differences now recognized between allopatric populations within, for example, Pan troglodytes, Gorilla gorilla, Pongo pygmaeus and Papio hamadryas as well as other African mammals, it is not surprising that contemporaneous hominid populations as geographically distant as Chad and Ethiopia, Kenya and Tanzania would differ in morphology, regardless of whether they are classified as species or subspecies. Here we do not choose to name a new species, recognizing that more detailed comparisons are necessary before the taxonomy of this Bahr el Ghazal hominid can be resolved.¹

Here, he and the other authors of the paper clearly feel that the state of the discipline is sound enough to make educated pronouncements about the fossil record.  In all of Pilbeam's papers, it is clear that he is committed “evolutionist.” As with all palaeoanthropologists, he accepts that there may be aspects of the study that are not known or poorly understood but, of the central tenet: that humans have evolved, there is clearly no doubt.  Thirty six years is a long time in the history of a scientific discipline.

How good is our understanding of the human fossil record now?  Here is what another distinguished professor of anthropology, Richard Klein, has to say:

In the absence of fossils, Darwin could not have predicted the fundamental pattern of human evolution, but his evolutionary theory readily accommodates the pattern we now recognize. Probably the most fundamental finding is that the australopithecines, who existed from at least 4.5 million to 2 million years ago, were distinguished from apes primarily by anatomical specializations for habitual bipedalism, and it was only after 2 million years ago that people began to acquire the other traits, including our unusually large brains, that readily distinguish us from the living apes. The greatly expanded fossil record shows that the australopithecines comprised multiple species, and it suggests that our own genus, Homo, descended from one of these about 2.5 million years ago.²

Note the phrase “the greatly expanded fossil record.” Recall the two compendia on this fossil record I mentioned in the first part of this response. Menton clearly is unfamiliar with this record and his attempts to discredit it are shallow, as a result.

To recap:

• He claims that “evolutionists” just accept similarities between fossil bones of living men and fossilized apes as evidence of ancestry. Such a statement betrays a lack of understanding of homology, functional morphology and the modern study of evolutionary systematics. It glosses over important skeletal structures that arose during our ancestry and which separate our direct ancestors from all apes, fossil or otherwise.
• He massively under-emphasizes the size of the human fossil record and the complexity of it, simply dismissing it with no examination or explanation.
• He suggests that research projects cannot be undertaken based on pictures and measurements of fossil hominins.  This is absurd.  There is no scientific discipline that does not rely on published reports.  Moreover, this is a peculiar statement coming from a professor of anatomy, who must have, during his tenure as a professor, read countless articles on aspects of anatomy in which there were published measurements and pictures.  What was he to make of those?  Did they not constitute real research on which he based his own?
• He mistakenly calls a spider monkey an ape, bringing into question his understanding of basic primate taxonomy.  Further, while his anatomical specialty seems to have been at the cellular level, he betrays a peculiar lack of understanding of human morphological functional interrelatedness by suggesting that the carrying angle of hominins can be dissociated from hip, limb and cranial morphology.  While it may be true that some apes have a similar carrying angle to humans, not a one of them has a foramen magnum at the base of the skull, angled femoral condyles, or a flat, wide pelvis.  Further, these derived traits show up in the fossil record around 3.7 million years ago.  How did he miss these things?  When I took gross anatomy and physiology, I was required to learn not just developmental biology, but functional and comparative morphology.  Has he forgotten his?
• He writes that Ardipithecus, Orrorin, Sahelanthropus, and Kenyanthropus all have “obviously ape skulls, ape pelvises, and ape hands and feet” despite the fact that only one of these finds preserves the skeletal parts he references. This suggests that he never even bothered to look at the reports detailing these finds.  To make such errant, blanket statements about them is incompetent and sloppy. 
• He cherry-picks quotes that support his position and ignores ones that do not.  While he calls A. afarensis “long-armed knuckle-walkers” and suggests that palaeoanthropologists Stern and Susman³ argue that it is an ape, he carefully ignores other paragraphs from their article, in which they clearly argue that it is transitional between apes and humans, even using the phrase “missing link.”  He then (again, oddly for an anatomist) ignores other critical morphology of A. afarensis that clearly indicates its transitional status.
• He writes that Neandertals were considered human but have recently been denigrated to non-human status, when in fact, that is precisely backwards.  From their initial discoveries, Neandertals were considered subhuman^4,5 and it has only been within the last thirty years that their relationship to modern humans has been reassessed, inviting claims by some that they represent simply an earlier version of us and incorporating new genetic knowledge of interbreeding between Neandertals and modern humans⁶.  

This is a badly written post that shows little in the way of actual research.  He seems to misunderstand basic anatomy, gets fossil descriptions wrong, quote-mines to show only what appears to support his position and seems to show no understanding of basic evolutionary biology.  His demeanor is pompous and contemptuous and his treatment of the subject matter invites scorn.

I have absolutely no doubt that Dr. Menton is a bible-believing Christian and that, as such, he is an asset to the kingdom.  I also believe that, like so many other young-earth creationists I am familiar with, he treats the fossil material and the discipline of evolutionary biology with dishonesty and lack of integrity.  This saddens me since it, as with all of creation, reflects the goodness, glory and, importantly, the awesomeness of God.  Further, it is a bad witness and pushes people away from God. 

¹Brunet, M, Beauvilain, A, Coppens, Y, Heintz, E, Moutaye, A, Pilbeam, D. (2014) The first australopithecine 2,500 kilometres west of the Rift Valley (Chad). Nature 378, November 16, 1995
²Klein, R. G. (2009). Darwin and the recent African origin of modern humans. Proceedings of the National Academy of Sciences, 106(38), 16007-16009.
³Stern Jr, J. T., & Susman, R. L. (1983). The locomotor anatomy of Australopithecus afarensis. American Journal of Physical Anthropology, 60(3), 279-317.
⁴Boule, M. (1913). L'homme fossile de La Chapelle-aux-Saints: Masson.
⁵Virchow, Rudolf. Untersuchung der Neanderthal Schädels. 1872.
⁶For example: Sankararaman S, Patterson N, Li H, Pääbo S, Reich D (2012) The Date of Interbreeding between Neandertals and Modern Humans. PLoS Genet 8(10): e1002947. doi:10.1371/journal.pgen.1002947
⁷Krings, M., Stone, A., Schmitz, R. W., Krainitzki, H., Stoneking, M., & Pääbo, S. (1997). Neandertal DNA sequences and the origin of modern humans. Cell, 90(1), 19-30.

BioLogos, Ken Ham and David Menton—A Response, Part IV

This is the fourth part of my response to David Menton's post on human origins.  Links to the first three appear below this post.  Menton continues his ham-fisted, ignorant attack on the human fossil record.

Point 8.  He writes:  

Many apemen are merely apes that evolutionists have attempted to upscale to fill the gap between apes and men. These include all the australopithecines, as well as a host of other extinct apes such as Ardipithecus, Orrorin, Sahelanthropus, and Kenyanthropus. All have obviously ape skulls, ape pelvises, and ape hands and feet. Nevertheless, australopithecines (especially Australopithecus afarensis) are often portrayed as having hands and feet identical to modern man; a ramrod-straight, upright posture; and a human gait.

The best-known specimen of A. afarensis is the fossil commonly known as “Lucy.” A life-like mannequin of “Lucy” in the Living World exhibit at the St. Louis Zoo shows a hairy, humanlike female body with human hands and feet but with an obviously apelike head. The three-foot-tall Lucy stands erect in a deeply pensive pose with her right forefinger curled under her chin, her eyes gazing off into the distance as if she were contemplating the mind of Newton.

Few visitors are aware that this is a gross misrepresentation of what is known about the fossil ape Australopithecus afarensis. These apes are known to be long-armed knuckle-walkers with locking wrists. Both the hands and feet of this creature are clearly apelike. Paleoanthropologists Jack Stern and Randall Sussman2 have reported that the hands of this species are “surprisingly similar to hands found in the small end of the pygmy chimpanzee–common chimpanzee range.” They report that the feet, like the hands, are “long, curved and heavily muscled” much like those of living tree-dwelling primates. The authors conclude that no living primate has such hands and feet “for any purpose other than to meet the demands of full or part-time arboreal (tree-dwelling) life.” 

Some background involving the Miocene apes. At the beginning of the Miocene epoch, apes had largely generalized skeletal structures, with few of the adaptations that we see in the modern apes, or in humans.  Toward the end of the Miocene, biomechanical adaptations are seen in many of the apes.  For example, Oreopithecus has developed a locomotor pattern seen in modern non-human apes (although it was mis-identified by Casey Luskin as bipedal).

Menton, having taken us through the differences between apes and humans, suggests that Ardipithecus, Orrorin, Sahelanthropus and Kenyanthropus all have “obviously ape skulls, ape pelvises, and ape hands and feet.”

Really?

• Kenyanthropus consists of a single skull find that is so badly crushed that most researchers have pretty much written it off as being unusable in taxonomic reconstruction.
• Sahelanthropus is also a single skull find that was also crushed and may, in fact, be a surface find.
• Orrorin tugenensis is a collection of post-cranial remains, the most important of which is a partial femur, which showed clear adaptations toward bipedality. 
• Ardipithecus ramidus consists of both cranial and post-cranial remains, including both hands and feet.  Here is what Owen Lovejoy and colleagues wrote about it in 2009:

“The gluteal muscles had been repositioned so that Ar. Ramidus could walk without shifting its center of mass from side to side. This is made clear not only by the shape of its ilium, but by the appearance of a special growth site unique to hominids among all primates (the anterior inferior iliac spine). However, its lower pelvis was still almost entirely ape-like, presumably because it still had massive hindlimb muscles for active climbing.”

How does Menton describe the locomotion of modern apes?  He writes:

These animals manage to keep their weight over their feet when walking by swinging their body from side to side in the familiar “ape walk.” 

Yet he calls Ardipithecus “merely” an ape. By his own description, Ardipithecus is clearly not “merely” an ape. Did he just miss this detail, or did he simply choose not to include it?

To recap this point,  he writes that all of the finds he mentions have “obviously ape skulls, ape pelvises, and ape hands and feet,” and yet we find that only one of the finds has those body parts preserved.  He, further, ignores critical morphology on the Ardipithecus remains to make it seem as if it has no hominin adaptations.  How are we to believe what he writes when he so incompetently describes the fossils he is denigrating?

Point 9: In quoting Stern and Susman, here, again, Menton picks and chooses what he wants to use and doesn't tell his audience other critical information that undercuts his position.  Menton writes as if Australopithecus afarensis were only an ape, yet Stern and Susman write, in their conclusion:

In our opinion A. afarensis is very close to what can be called a “missing link.” It possesses a combination of traits entirely appropriate for an animal that had traveled well down the road toward full-time bipedality, but which retained structural features that enabled it to use the trees efficiently for feeding, resting, sleeping, or escape. prior to the discovery of the Hadar remains, one could not have predicted precisely what combination of traits would be found in a transitional form such as A. afarensis.

These writers, who, unlike Menton, examined the remains directly, clearly did not conclude it was merely an ape but, in fact, a transitional form between the apes that came before, and the hominins that came after.

But worse, Menton completely ignores other characteristics of A. afarensis that don't just undercut his position that it is merely an ape, they destroy it. 

• The first premolar in apes (or bicuspid if you prefer) is long and rotated toward the front of the mouth. This is so it can constantly sharpen the maxillary canine as the ape bites down. This is known as a "sectorial premolar". In humans, this tooth is rotated so that the cusp division is parallel to the tooth row and does not stick up beyond it. The maxillary canine is, correspondingly, short. In Australopithecus afarensis, this tooth is rotated HALF-WAY and partially sticks up from the tooth row. The canine is shortened as in modern humans.

• The palate of the mouth in apes is shaped like a hard "U" with the back teeth parallel to each other. In humans, the palate is more "V" shaped. In A. afarensis, it is intermediate between these two shapes.

• In apes, there is a distinct space between the canine and the first premolar, called a diastema. In humans, this space is absent. In A. afarensis, a diastema is present but it is remarkably reduced in size over the ape condition.

In other instances, some characteristics are completely ape-like and some are completely human-like. For example:

• The digits (phalanges) on both the hands and feet are curved, as in apes. In humans, they are straight.

• The pelvis is flared (wide from side to side) and short from top to bottom, as in humans.

• The hole in the skull where the spinal chord exits the brain, the foramen magnum, is located on the bottom of the skull in Australopithecus afarensis, as in humans.  Having a hole at the base reflects a bipedal gait.

• the knee joint, which preserves the bottom (distal) section of the femur and the top (proximal) section of the tibia shows that the femur is angled, as in humans. This is the "carrying angle" of which Menton wrote. The A. afarensis position, once again, reflects bipedalism.

These characteristics are exactly what you would expect to find in a transitional species: some characteristics transitional, some ape-like and some human-like. Most of the above information was taken from Lucy: The Beginnings of Humankind and Johanson et al. (1982) but can be found in most textbooks about this subject.  It is amazing that Menton went to no effort to locate this information before dismissing A. afarensis' transitional status without thought.    It is, further, amazing that Ken Ham would hold Menton's post up as being authoritative when it is so badly researched and written.

On to Part V. 

BioLogos, Ken Ham and David Menton—A Response, Part I

I thought that I would respond to Ken Ham's veiled attack on my BioLogos series and subsequent referral to the post on human origins by David Menton in one lump post but it is becoming too massive and straggly and it is taking too long, so I will respond to it in a series of posts, starting with this one.  Here goes:

As I mentioned last week, Ken Ham took a potshot at me on the AiG page.  His post is titled Does the Bible Teach Human Evolution.  In it, he writes:

BioLogos is at it again! Earlier this week, I wrote about how they’re indoctrinating children, teens, and young adults with theistic evolution. But now they’re running (for the second time) a blog series on the supposed evidence for human evolution!
Now, evolutionists have claimed for decades that humans evolved from an ape-like ancestor over long ages. But the so-called evidence they’ve produced for their idea doesn’t support it at all. In fact, many of the alleged fossils of “missing links” have turned out to be hoaxes, and many others are easily identified as either fully human or fully ape.

Really?  I can only think of one hoax in the last hundred years, Piltdown, and that was uncovered by scientists, using scientific methods, in 1953.  He continues:

Dr. David Menton, an AiG speaker and a retired professor of anatomy at Washington University School of Medicine in St. Louis, Missouri, explains how evolutionists create ape-men.

Let's follow the link and see how we create “ape-men.”  He begins his post by laying out Biblical Starting Assumptions and Evolutionary Starting Assumptions.  The hermeneutic validity of AiG's (and by extension, the young earth creationist) doggedly literalist position has been been addressed by thousands of writers over the course of the last two thousand years and will not be addressed in-depth here.  I will, instead, address his points regarding human evolution.

Point 1.  He writes:

Since evolutionists generally do not believe that man evolved from any ape that is now living, they look to fossils of humans and apes to provide them with their desired evidence. Specifically, they look for any anatomical feature that looks “intermediate” (between that of apes and man). Fossil apes having such features are declared to be ancestral to man (or at least collateral relatives) and are called hominids. Living apes, on the other hand, are not considered to be hominids, but rather are called hominoids because they are only similar to humans but did not evolve into them. Nonetheless, evolutionists are willing to accept mere similarities between the fossilized bones of extinct apes and the bones of living men as “proof ” of our ape ancestry. 

First, the wording is such that it gives the impression that the fossils we find and the characteristics that we identify as transitional are those that we desire to.  What we want is immaterial.  Our understanding of human evolution has changed as we have uncovered new evidence.  This process has often been messy and straggly.  If we tailored the fossil record to fit our evolutionary preconceptions, it would not look anything like what it does.  We don't look for features that are "intermediate."  We look for traits that are derived in a particular direction and differentiate them from traits that are retained.  In this way, we can identify lineages based on shared derived traits and identify splits in the fossil record between lineages.  As was recently written over on Panda's Thumb, taxonomists cannot identify ancestor-descendent relationships.  It is not possible to do so given our understanding of the fossil record and taxonomy.  What we can do, and do quite well, however, is identify related taxa and place them in taxonomic relationship to each other.  That is how we have identified Ardipithecus and differentiated it from other late Miocene apes.  Whether or not Ardipithecus is on the line that led to humans or not is not known.  What is known is that it had traits derived in the hominin line (shortened canines, facultative bipedality) while still maintaining a large number of retained traits linking it to other Miocene apes (long arms relative to legs, adaptations to arboreality, a small ape-like brain-case).

Point 2:

Though many similarities may be cited between living apes and humans, the only historical evidence that could support the ape ancestry of man must come from fossils. Approximately 95 percent of all known fossils are marine invertebrates, about 4.7 percent are algae and plants, about 0.2 percent are insects and other invertebrates, and only about 0.1 percent are vertebrates (animals with bones). Finally, only the smallest imaginable fraction of vertebrate fossils consists of primates (humans, apes, monkeys, and lemurs).   

What is meant by the “smallest imaginable fraction?” If you have a sample size of five hundred, 0.01% would be 5. That is not much to go on. On the other hand, if your sample size is huge, say on the order of hundreds of billions of fossils, which reflects the best estimates, then 0.01% would still be over one billion fossils.  Even if only a fraction of that, 0.01%, related to human origins, we would still have over a million fossils relating. Recently, Ian Tattersall and Jeffrey Schwartz put together a four-volume encyclopedia set of human fossil remains.  Each volume is at least 400 pages.  There are a total of 149 listed, many of which have multiple individuals represented.  And this represents only the most complete sites.  In 1977, Kenneth Oakley published, in four volumes, the Catalog of Fossil Hominids, a listing of every fossil site known to that point.  There are literally hundreds of sites listed.

Is it true that we have gaps in our understanding of human evolution because our fossil record is incomplete?  Yes, it is, but what we have is a whole lot better than Menton suggests.  The site of Hadar alone, which is where the Australopithecus afarensis find Lucy was discovered, yielded over 250 hominin fossils alone in the 1970s.  Many more have been found since.   Menton makes a blanket assumption that, since we have only a fraction of the total fossil record, that is not much.  Here, he is mistaken.

Part II here.

New Study: Ardipithecus ramidus Derived In Human Direction

According to Bill Kimbel and colleagues, the skull of Ardipithecus ramidus shows tell-tale signs of being derived in the human direction away from great apes.  From Science Daily:

White's field-research team has been recovering fossil remains of Ardipithecus ramidus in the Middle Awash research area, Ethiopia since the 1990s. The most recent study of the Ardi skull, led by Suwa, was published in Science in 2009, whose work (with the Middle Awash team) first revealed humanlike aspects of its base. Kimbel co-leads the team that recovered the earliest known Australopithecus skulls from the Hadar site, home of the "Lucy" skeleton, in Ethiopia.

"Given the very tiny size of the Ardi skull, the similarity of its cranial base to a human's is astonishing," says Kimbel.

The cranial base is a valuable resource for studying phylogenetic, or natural evolutionary relationships, because its anatomical complexity and association with the brain, posture and chewing system have provided numerous opportunities for adaptive evolution over time. The human cranial base, accordingly, differs profoundly from that of apes and other primates.

In humans, the structures marking the articulation of the spine with the skull are more forwardly located than in apes, where the base is shorter from front to back and the openings on each side for passage of blood vessels and nerves are more widely separated.

Given that the post-cranial remains from Ardipithecus suggest facultative bipedalism, this is not so surprising. If you are going to walk upright at all, you need to be able to see where you are going. This information, in conjunction with the new appraisal of the Orrorin tugenensis remains strongly suggests that, while Orrorin was at or near the junction of the last common ancestor, Ardipithecus, at 1.6 million years later, is quite a bit beyond it. It also reinforces what a terrible model the modern apes are for early human morphology.

Orrorin tugenensis: As Close to the Last Common Ancestor As We Have Gotten?

Based on work by SUNY Stoney Brook, it has been learned that the femur of Orrorin tugenensis, the six-million year-old presumed hominin, also called the "millenium man," has a mix of traits that align it with not just early hominins but late Miocene apes.  Science Daily reports:

According to Dr. Almécija, their study for the first time compared the six-million-year-old Millenium Man femur (called BAR 1002'00) using state-of-the-art morphometric techniques to not only other available hominin fossils but also great apes, hylobatids (ie, gibbons and siamangs), and most importantly to fossil apes that lived in the Miocene. The analysis included more than 400 specimens.

"We discovered that Orrorin's femur is surprisingly 'intermediate' in both age and anatomy between quadrupedal Miocene apes and bipedal early human ancestors," said Dr. Almécija. "Our paper provides quantitative results of the Orrorin femur as a unique mosaic and stresses the need to incorporate fossil apes into future analyses and discussions dealing with the evolution of human bipedalism, an investigation that should stop considering chimpanzees as default living 'starting point' models."

As the authors note, this is not so different from what was concluded about the gait of Ardipithecus ramidus and that the examination of that hominin led to the idea that, perhaps, modern apes are poor models for early hominin morphology and that the modern apes diverged from the last common ancestor (LCA) in entirely different directions. It is exciting to get to a point where there are obviously transitional characters between hominins and non-hominins. 

The other thing that is quite striking is that there is no obvious dividing line between being a quadruped and a biped and that the transition took some time and was gradual.  Don Johanson, in Lucy: The Beginnings of Humankind, word:

You don’t gradually go from being a quadruped to being a biped. What would the intermediate stage be–a triped? I’ve never seen one of these.

It appears that he may have been wrong, at least about the gradual part.

One Reason Palaeoanthropology Is So Hard

The Star, from South Africa has a nice story on a hunk of rock that contains the second of the skeletons pulled from the South African cave site of Malapa, the first of which was the nice juvenile Australopithecus sediba individual. Shaun Smillie writes:

Last night, in Shanghai, China, scientists from Wits University’s Institute for Human Evolution announced the discovery of fossils buried deep in a piece of rock about a metre in diameter. They are believed to be the remains of Karabo, one of the two Australopithecus sediba skeletons that were discovered at Malapa, in the Cradle of Humankind, in 2009.

Karabo’s partial skeleton was removed from the Malapa site, but the rock appears to contain more of his bones.

One is reminded of the arduous task that awaited Raymond Dart as he sat before the stone breccia that contained the first australopithecine to be discovered in South Africa. It took him seventy three days to pry apart the limestone to extract the remains.

This is something that is often missed by the popular press and creationists: fossils are rare and complete fossils are even rarer. And, unlike the kind of archaeological work that goes on in neolithic or bronze age sites, human fossil remains are usually found in concretions—limestone or some other hard rock—and are very hard to extricate cleanly. In the case of Ardipithecus ramidus (or “Ardi”), the extraction took years because the bones were so brittle. Jamie Shreeve writes in National Geographic that as soon as bones were removed, they were doused with hardener to make sure they did not fall apart. Then, once they are removed comes the equally arduous task of trying to reconstitute the pieces. Complete skulls are rare and even the most complete ones have to be put back together. Once we have them, they are great tools for discovering how we came to be and the stages that got us here. But it takes a lot of work just to get to that point. It will be nice when we get the second A. sediba skeleton out to see how it compares to the one we already have.

A New Species of Hominin Coeval With Lucy?

Great Googlymoogly! A new discovery has been made in the Afar triangle that indicates that a similar species of Australopithecus that was not A. afarensis lived alongside them. Science Daily writes:

“The Burtele partial foot clearly shows that at 3.4 million years ago, Lucy’s species, which walked upright on two legs, was not the only hominin species living in this region of Ethiopia,” said lead author and project leader Dr. Yohannes Haile-Selassie, curator of physical anthropology at The Cleveland Museum of Natural History. “Her species co-existed with close relatives who were more adept at climbing trees, like ‘Ardi’s’ species, Ardipithecus ramidus, which lived 4.4 million years ago.”

There is nothing to dictate that there were no intermediates between Ar. ramidus and Au. afarensis or that there were not several hominins on the landscape at this point. We know that there were two species of Ardipithecus. It is possible that this represents a descendent of Ar. ramidus or a descendent of a species that lived at the same time as Ardi and gave rise to a hominin that was more arboreal in nature. Until we have more to go on, it will be hard to construct any relationships that are even provisional.

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Did Competition Put Us On Our Feet?

Simply, yes. That is not earth-shattering. Cambridge News has a story on work done with chimpanzees that seems to confirm that behavioral alterations in higher level primates help with competitiveness. They write:

Anthropologists studying chimpanzees found the great apes, who usually walk on all fours, walk upright and free their hands for carrying when they need to grab more hard-to-find resources in one go, in the face of competition.

The team from the University of Cambridge and Kyoto University in Japan believe the benefit of “first come, first served” and getting a bigger share of scarce food supplies could, over a long period of time, have led some of our earliest “hominin” ancestors to evolve into “bipedal” primates walking on two legs permanently instead of four.

This has always been part of the bipedality model, that early hominins exploited the forest/fringe environment where they could get what they needed from the trees and from the savannas. The fact that Ardipithecus ramidus demonstrated bipedality in a forested environment sort of threw cold water on the more conservative of those models but it is also clear that even the level of bipedality continued to evolve over time and that, by the time later australopithecines had completely human, obligate bipedal locomotion, these hominins were living in the open and competing for those resources. It was at this point that our brains began to expand as well.

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The Role of Savannahs in Human Evolution

It now appears that grassland savannahs stretched further than originally thought during the critical time when human precursors became bipedal. As the Gence France Presse reports:

"There have been open habitats for all of the last six million years in the environments in eastern Africa where some of the most significant early human fossils were found," said Thure Cerling, a professor at the University of Utah and lead researcher of the study.

"Wherever we find human ancestors, we find evidence for open habitats similar to savannahs - much more open and savannah-like than forested," he said in a statement.

It still remains to be explained how Ardipithecus developed a bipedal gait within a forest environment, though.

Bernard Wood and Terry Harrison on Early Human Origins

Bernard Wood and Terry Harrison, two of the preeminent scholars in the study of human origins think that we are assimilating too many fossils into our family tree. In an article in PhysOrg, the author writes:

The paper, "The evolutionary context of the first hominins," reconsiders the evolutionary relationships of fossils named Orrorin, Sahelanthropus and Ardipithecus, dating from four to seven million years ago, which have been claimed to be the earliest human ancestors. Ardipithecus, commonly known as "Ardi," was discovered in Ethiopia and was found to be radically different from what many researchers had expected for an early human ancestor. Nonetheless, the scientists who made the discovery were adamant it is a human ancestor.

Wood and Harrison have a point here. One of the things that we castigate those that are unfamiliar with evolutionary theory about is “unilineal” thinking—that you can have transitional forms in the fossil record that do not reflect direct ancestry but “collateral” ancestry. This is especially true in the transition from the late theropod dinosaurs to birds. Yet, because we are talking about our own lineage, we tend to slip into a unileal way of thinking. Witness the brouhaha about Ida last year. Everyone wanted to roll her into the human fossil line even though there was no concrete evidence of such.

This does not mean that Sahelanthropus, Orrorin and Ardipithecus are not transitional. It just means that there is no direct evidence that they are ancestral to the human line. In the article, Wood and Harrison write:

There is no reason why higher primate evolution in Africa in the past ten million years should not mirror the complexity observed in the evolutionary histories of other mammals during the same time period. Nor is there any reason, especially with the lessons from Ramapithecus and Oreopithecus fresh in the minds of researchers, to assume that hominins should not be prone to the same limitations and uncertainties of phylogenetic analysis as other fossil primates.¹

This does not make them any less worthy of study or of producing excitement in the palaeoanthropological community.

¹Wood B., Harrison T. (2011) The evolutionary context of the first hominins. Nature 470:347-352.
10.1038/nature09709

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