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The Human Fossil Record, Part 5: The Dispersal of the Australopithecines

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June 16, 2011 Tags: Human Origins

Today's entry was written by James Kidder. Please note the views expressed here are those of the author, not necessarily of BioLogos. You can read more about what we believe here.

As we learned in the previous post, up until approximately three million years ago, australopithecines were restricted in variation to Australopithecus afarensis, the successor to Australopithecus anamensis. This hominin has been found in the north at Hadar, Ethiopia, and as far south as Tanzania. Subsequent to this time period, however, the australopithecines as a genus underwent a dramatic expansion and, eventually, would be found in all of eastern and possibly central Africa.

The Lack of Acceptance of Australopithecus and the Piltdown Forgery

Raymond Dart, discoverer of the first australopithecine, the Taung child skull, met with lukewarm to tepid response when he described his find in the journal Nature. One of the reasons for this is that, to the early 20th century eye, it looked very ape-like, and it was hard for many to grasp that there was any connection between it and the forms that followed. The other reason is that the path to humanity was thought to already exist elsewhere in the form of Eoanthropus dawsoni, the fossil remains from the Piltdown Commons, in England.

The Piltdown forgery ranks as one of the best scientific hoaxes of all time. Charles Dawson unearthed purported hominin fossil remains from a gravel pit at Piltdown Commons, East Sussex County, in 1912 that consisted of a mostly complete skull and partial jaw in association with extinct mastodon and hippopotamus fossils (See Figure 1). This was published in the Quarterly Journal of the Geological Society (Dawson and Woodward 1913) and became the crown of English anthropology, eliciting the support of most of the top anthropologists and anatomists of the day, including Sir Arthur Keith, Sir Arthur Smith-Woodward, Grafton Eliot Smith and William King Gregory.

The find, which was dated biostratigraphically to the Middle-Pleistocene, showed that evolution of the braincase preceded evolution of the rest of the head and jaw. Consequently, when Dart’s australopithecine find was described with its human-sized teeth and small braincase, it didn’t fit the pattern established by Piltdown and was, thus, denigrated by the researchers in the field. However, as more human remains were found in the 1930s and 1940s that resembled Dart’s find, Piltdown’s uniqueness became peculiar. Further, nothing else emerged from England itself that resembled Piltdown. As researchers around the globe began to assemble their human origins charts and timelines, Piltdown became increasingly hard to accommodate within any evolutionary framework.

In the early 1950s, Kenneth Oakley and Josef Weiner secured the rights to examine the remains using a new relative dating method that had been recently been calibrated, fluorine analysis. The basis behind this technique is simple: as organic material sits in the ground, it soaks up fluorine. The longer it is there, the more fluorine it soaks up. In this way, some fossils could be said to be older than others and rough comparisons could be made. Oakley’s analysis initially suggested that the find was much more recent than originally thought (Oakley and Hoskins 1950) This sowed the first seeds of doubt about the find. Eventually, a more detailed analysis was undertaken by Weiner, Oakley and Wilford Le Gros Clark, resulting in the publication “The Solution of the Piltdown Problem” (Weiner, Oakley and Le Gros Clark 1953). They discovered that the teeth had been filed down to make them look old, the jaw and isolated teeth were not the same age as the cranium but were, rather, modern in age, and that the remains had been stained to give them an old appearance. These findings led to a public outcry and the whole house of cards came down. Subsequent analyses revealed that the jaw was, in fact, that of an orangutan, the mastodon and hippo remains had metal knife marks, and the fossil mastodon remains were from Tunisia.

To this day, the identity of the Piltdown forger remains unknown. The weight of suspicion has fallen, in recent years, on the original discoverer, Charles Dawson, who likely had the means to carry out the prank. Sadly, Dawson contracted septicemia and passed away in 1916, possibly carrying this information with him to his grave. One of the best accounts of this forgery is by John Walsh, called Unraveling Piltdown (Walsh 1996). Perhaps one of the most important lessons from the Piltdown experience is that it demonstrates a classic example of the self-corrective capacity of science. Once the weight of Piltdown had been removed from the field, the australopithecine discoveries in Africa began to make sense in the context of the larger picture of human origins.

Australopithecine Phylogenetics

Australopithecine systematics is, like that of the earliest birds, a confused business, with many different competing hypotheses about where each species fits in the grand scheme of things (See Figure 2 below). To top this off, it is not clear from which of these lines Homo emerged.

Based on the best current weight of evidence, it is now commonly thought that between two and three lineages of australopithecines emerged from the line that came from A. afarensis. It is not possible to infer direct ancestor-descendent relationships between these forms. All that we can surmise at the moment is that at around 3.0 million years ago, A. afarensis was the only hominin on the landscape and at 2.5 million years ago, there were multiple forms, spanning the geographical distance between Ethiopia and South Africa with likely remains in Chad.

The East African Forms

Australopithecine species tend to be found in two general forms: a gracile, or smaller and lightly built, form and a robust, or larger and more heavily built, form. While some have argued that the robust australopithecines belong in a separate genus, Paranthropus (Grine 2007), this is a minority position within the field. For our purposes, they will be subsumed within the genus Australopithecus.

At around 2.5 million years ago, a new form was found in Ethiopia that appeared to be a scaled up version of A. afarensis. Called Australopithecus aethiopicus, this species had a long, low cranium with flared cheekbones and attachment areas for very powerful chewing muscles on its face (See Figure 3). To go with this, A. aethiopicus also had, on the top of its head, a large sagittal crest. Work with modern-day gorillas, which also have this feature, has shown that this is not a genetic trait but appears as a result of bone deposition on the top of the head through continuous grinding of nut and plant substances. Unlike the gorilla version, however, which is focused directly on the top of the cranium (vertex), the A. aethiopicus manifestation is toward the back of the cranium. This form had an average cranial capacity of around 410 cubic centimeters. For comparison purposes, the average modern human cranium is approximately 1450 cubic centimeters in capacity while chimpanzees average 375 cubic centimeters.

Also from this time period is a form similar to A. afarensis in brain size and gracility, Australopithecus garhi (“surprise” in the Afar language). The teeth are slightly larger than those of afarensis (See Figure 4). In overall body shape, however A. garhi was far more modern, with the ratio of upper arm length to upper leg length much closer to those of later hominins (Asfaw et al. 1999).

Slightly later in time, from around 2.2 million years ago, came Australopithecus boisei. This form was originally found in 1959 by Mary Leakey, in the Olduvai Gorge area near the Serengeti Plains, in Tanzania, where she and her husband, Louis, had been digging since 1951. This is known as a hyper-robust australopithecine. Comparisons with A. aethiopicus strongly suggest that the facial architecture of A. boisei is very similar, yet larger in size. This has led researchers to surmise that there is an ancestor/descendent link between the two species. A. boisei has a slightly larger cranial capacity of 510 cubic centimeters but otherwise retains all of the characteristics of A. aethiopicus, including the sagittal crest, the scooped-out facial appearance and wide, flaring cheek bones (see Figure 5). It has been hypothesized that these forms subsisted primarily on a vegetative diet consisting of hard nuts, roots and berries because the rear teeth were much larger than the front ones and considerably larger than those of A. afarensis. This eventually led to the nickname “nutcracker man.” This hypothesis has recently been challenged, however, by research that suggests that the primary diet of this hominin was grasses (Cerling et al. 2011). A. Boisei is found down to approximately 1.2 million years ago.

In our next post we will look at the South African forms, as well as the extinction and importance of Australopithecus.

James Kidder holds a Ph.D. in Biological Anthropology from the University of Tennessee (UT). He currently employed as an instructor at UT, and as a science research librarian at Oak Ridge National Laboratory. He has been involved in the Veritas Forum at UT and runs the blog "Science and Religion: A View from an Evolutionary Creationist/Theistic Evolutionist."

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Pete D - #62653

June 16th 2011

Could you address the dispersal of modern humans from the Tower of Babel? Or is that allegorical?

Jimpithecus - #62654

June 16th 2011

Hi Pete.  As with the problems with a global flood, by the time the Tower of Babel story is said to have taken place, there were already hundreds of thousands of people all over the world.  The earliest evidence of modern human habitation in the New World (the Americas) is between 15 and 25 thousand years ago, in Australia, it dates back to around 50 thousand years and, of course, in other parts of the Old World, you have continuous habitation back several hundred thousand years by Homo erectus and then Homo sapiens.

As Paul Seely writes: “The story of the Tower of Babel, has bits and pieces in Mesopotamian
thought: a story of a time when all humans spoke the same language BUT
in the Mesopotamian account, this is related to the Paradise of
creation, not a ziggurat. Also, there were temple-towers with names
that spoke of “high as heaven.” The biblical story is woven into the
history: if a flood destroyed all mankind except those on the ark, then
the first few generations thereafter would all be speaking the same
language. To answer the question, Where did all the languages come from?
the story invents a judgment on the Babylonians, but this is not so
much etiological as it is theological: “Babel” which at least in popular
Babylonian thought meant “gate of God” is interpreted as “confusion.” 
There may also be an actual historical event in the background when
Sumerian was displaced by another Language.”

Does this help?

KevinR - #62758

June 21st 2011

This is really interesting, if not funny. Strange how one finds it acceptable to believe the Babylonians but utterly refuses to believe the bible. I assume that the answer given to the question comes from an atheist. One that is intent on destroying any credibility of biblical thought by any means whatsoever.
Hence of course why one should NOT believe in evolution and claim to be a Christian. The two just doesn’t go together. If you believe in evolution you automatically have to believe in millions of years which completely decimates any consistency in a biblical world view. Believing in evolution is indistinguishable from being an atheist, as evidenced by this answer.

You either believe the word of God as it stands or else you have to find hundreds of excuses for all the improbable things said in there relative to what evolution teaches.

beaglelady - #62655

June 16th 2011


Loved the article!

What is the difference between Australopithecus boisei and Pananthropus bosei? Or are these different names for the same specimen? I’m wondering because Natural History magazine just had an article about the P. bosei—explaining that the high levels of carbon-13 found in it indicated a diet high in grasses and sedges, and that it needed a new nickname to replace “Nutcracker Man.” (Grass Man would be confusing—makes him sound like a pothead). 

I’m surprised it could chew grass at all—just look at how the teeth of horses evolved over time as its diet changed to grass. 

beaglelady - #62656

June 16th 2011

Does BioLogos have an official position on the Tower of Babel?

Jimpithecus - #62657

June 16th 2011

Beaglelady at 62656: Don’t know.  That might be a question for Pete Enns or Darrel Falk.

Jimpithecus - #62658

June 16th 2011

Beaglelady at 62655: The short answer is that some researchers think that the differences between A. africanus and A. robustus  and between A. aethiopicus and A. boisei are simply too great to subsume within one genus and another one is warranted.  Leading this charge was Fred Grine in the 1980s, who intially argued that the paranthropines represented  a monophyletic group, separate from the australopithecines.  There are those of us who see the paranthropine characteristics as simply being ramped up adaptations to the environment and that it is perfectly reasonable to see them all belonging to the australopithecines.  I sort of hint at that in this article. 

R Hampton - #62659

June 16th 2011

You might want to read Todd Wood’s latest blog entry (http://toddcwood.blogspot.com/). Regardless, Homo Sapiens have been on every continent - except Antarctica - for 10,000 years, long before the Tower of Babel.

Jimpithecus - #62700

June 18th 2011

I haven’t figured out Todd Wood yet.  He seems to thoroughly understand the genetic and evolutionary arguments for the positions involving not just non-primates but primates as well and is adept at refuting the standard creationist arguments against these positions

...and yet he doesn’t believe a word of it.  As they say in popular parlance: “What’s up with that?”

Jimpithecus - #62660

June 16th 2011

R Hampton,
   I saw that just today and didn’t have the energy to address it at the time.  I will probably do so in a future blog post.  Thanks for the heads up.

TruthSeeker - #62661

June 16th 2011

I was wondering if scientists know which species humans developed from. Also, why did all of these species that seem to be so complex die? In what way would humans out-compete these species and not other primates that exist still today? Any answers welcome.

Jimpithecus - #62666

June 16th 2011

Hi Truthseeker,
    The question of the origins of modern humans is one of the thorniest ones in human palaeontology and there are conflicting views about whether or not modern humans originated in only one area, Sub-Saharan Africa, or whether modern genes &ldquo;percolated&rdquo; through the genome and modern humans showed up in a multiregional fashion.  As far as the australopithecines dying out, what we find out is that they became overspecialized for their environment and then were outcompeted by the new kid on the block: HomoHomo appeared to have been a generalist and tracing the origin of Homo may involve trying to see which late surviving australopithecine was the most generalized in terms of subsistence and behavior. 

The non-human primates that exist today split off from the precursors of the australopithecines around 7 or so million years ago and their evolutionary trajectory took them to where they are today, with the baboons and other monkeys taking to the savanna while the gorillas and chimpanzees took to the forest. 

That help?

TruthSeeker - #62745

June 20th 2011

Yes, that does help. Thanks.

Jimpithecus - #62667

June 16th 2011

Okay, html fail.  That was supposed to be “percolated” but it didn’t read the smart quotes.

freetoken1 - #62675

June 17th 2011

Jimpithecus - #62666

Just being a bit pedantic, but human origins is a broader concept than just paleontology, so besides paleontology (per se) it’s also a problem for genetics etc.  By “problem” I don’t mean something that is derisive or derogatory (though certainly literalist creationists would like that to be so), but simply that it is a scientific question that is in the process of being addressed.

Also, continuing with the pedantry,

“The non-human primates that exist today split off from the precursors of the australopithecines around 7 or so million years ago…”

overly glosses the extent of changes in the primates.  E.g., the separation of old world monkeys from new world monkeys, the separation of the Hominoidea from the rest of the monkeys would be substantially before the australopithecine precursors split from the rest of the great apes.

Anyway, you may be well aware of all of these things, but I think many people, especially readers coming to BioLogos from religious sites, are not familiar with the scope of time under consideration, nor the breadth of the differences over time.

Pete D - #62676

June 17th 2011

Yes Jim, thanks. So no 6-day creation, no Adam and Eve, no Noachian Flood, no Tower of Babel based upon what we know from science. But the Resurrection is OK (but complicated because there was no Adam and Eve). Perhaps Biologos could do a chronological series of such bible stories so we can figure out how to determine which impossibilities to believe and which to consider as allegory. Maybe take on the Exodus and the parting of the Red Sea next? Or the brothers saved from the fire? Maybe Elijah’s challenge to Baal worshippers? What about the breeding of striped goats? Is it a difference between OT and NT authorship that renders one series of tales believable and one series not so?

KevinR - #62760

June 21st 2011

Fully agree. Once one starts down the evolutionary road one should really consider going all the way and abandoning a believe in Jesus as the Son of God.
It’s quite simple. One can come into Christianity with a believe in evolution but once one gets shown how that conflicts with the bible as it stands [in genesis 1] and is clearly understood, then one has the responsibility to either accept or reject the bible in it’s entirety.  To try and pretend that certain things are allegories and poetic whilst others are not leads to exactly the situation you describe.

I’d like to point out to those who believe they can cling to Jesus Christ whilst still believe in evolution: there will come a time [and it is right on us now] when you’ll be taunted and cajoled and compelled by atheists to state whether you believe in evolution or not - for the purpose of being accepted into some circle - and you’ll have to reject/denounce any creationist believe and also THOSE who believe in a young earth creation. Basically you who profess to be Christians[but believe in evolution] will have to join the enemies of God to persecute those very people whom you claim to side with. This kind of thing has already occurred in Britain and will become much more regular, whether you want to hear it or not.

Jimpithecus - #62678

June 17th 2011

Freetoken1 at 62675: You are correct in that primate palaeontology has its own story to tell and the split between the large bodied hominoids and the small bodied hominoids in the early Oligocene set the stage for what came later.  I just didn’t want to start that early.  The whole LCA question is a book in and of itself and I only touched on the basics.  It carries a lot of theological weight, though, that I skirted out of cowardice, because you are talking about the split between the line that became, eventually, us and the line that ended up at the modern-day chimpanzee.  It makes many people very uncomfortable to think that we share anything as basic as that.

Jimpithecus - #62679

June 17th 2011

Pete D.  One of the things that keeps coming up in the rudimentary reading that I have done on the OT texts is that the first eleven chapters of Genesis are written in such a different style than the rest of the OT that they are given their own name: “primeval history.”  I have read that the Pentateuch was edited, in some places, heavily, and some parts were added a bit later.  Different scholars disagree about this but if you read the creation story, the Adam and Eve story and the flood story, even in the face of the spiritual truths that those stories impart, they read like myth.  Further, they read very differently than the rest of the Bible.  Why would God impart a strictly literal story to His people when such a story would fly in the face of the accounts around them and be hard for them to understand?

Pete D - #62681

June 17th 2011

I agree that they read like myth. So do later books in the bible. My question is why are some myths believable and others are not - even when they fly in the face of things we know?

“Why would God impart a strictly literal story to His people when such a story would fly in the face of the accounts around them and be hard for them to understand?”

Do you think it would be more difficult for them to understand literal stories about the real, physical world than about some unseen, unknown, spiritual world? E.g. is it more difficult to for his people to understand that the earth was created over a long period of time rather than in 6 days? Or that various languages developed differently than as a means to confound cooperation on a massive construction project? The Resurrection story is also one that is common to other religions of the time period of the OT. Perhaps it is also not meant literally then.

Jimpithecus - #62702

June 18th 2011

That is just it, the later books read like narrative history or poetry or instruction manual.  There are no other parts of the Bible that read like the primeval history.   You write: “The Resurrection story is also one that is common to other religions of the time period of the OT.”  What other stories are you referring to? 

Pete D - #62706

June 18th 2011

I’m sure you are aware of Egyptian, Greek, and other religious mythologies involving resurrection. While details differ, the concept of coming back to life is not unique to Christianity. Whether the books read like primeval or narrative history, poetry, or instructions it is not the genre but the claims that are important. Elijah calling fire down from heaven rings no truer than a global flood. Abraham living to 175 as false a claim as Noah living to 950. The principles that lead us to conclude that Genesis 1 is not accurate as a literal history are the same that lead us to conclude that Exodus is not accurate. The reasons we do not believe Noah lived to 950 are the same as why we do not believe people can rise from the dead.

beaglelady - #62709

June 18th 2011

The principles that lead us to conclude that Genesis 1 is not accurate
as a literal history are the same that lead us to conclude that Exodus
is not accurate.

And what principles are these?

Pete D - #62715

June 19th 2011

@beaglelady - principles that require us to test our ideas by looking at evidence and reaching logical conclusions. The universe, solar system, and earth did not form in any way described by Genesis. Geology shows there was no global deluge. People did not originate from two original humans. Humans were not formed from dust. Women were not created from a man’s rib. Biology shows that genetic diversity could not arise from a bottleneck of a handful of related people (Noah and his family). Therefore, Genesis 1 is not accurate as literal history. Are such principles at odds with your own?

KevinR - #62762

June 21st 2011

Everything related to origins is simply man’s interpretation of the evidence at hand. You can take ALL the current evidence and re-interpret it to support the biblical point of view and it’ll be just as valid. The whole thing comes down to a philosophical stand - does God exist and did He create everything or not.

I just see that the evidence is far better explained by the biblical account than the evolutionary story. It’s far more consistent and logical whereas the evolutionary story violates the very principles it purports to derive from: Can something come from nothing[the singularity of the big bang is essentially nothing]?
How does things get more organized in a [closed] universe to the point where random physical processes gain the energy to assemble into stars, planets, life and ultimately human beings - a clear violation of the second law of thermodynamics and one which evolutionists do not want to be re-examined and published in scientific literature. The list of specifics which violates physical laws and plain common sense just goes on and on and on.
Evolution is a man-made myth for the express purpose of indulging one most base desires with no regard for a higher authority.

Pete D - #62767

June 21st 2011

Please suggest a biblical explanation for the CMB, distribution of isotopes, etc. These things were predicted by Big Bang theory (and confirmed with amazing accuracy), not interpreted in the context of Big Bang theory. In any case, evolution has nothing to do with the Big Bang so I don’t know why you are conflating the two. I really don’t think you have a clue what you are talking about.

Ronnie - #62803

June 22nd 2011

How does one ‘predict’ that an outcome is due to a speculated, unobserved event that supposedly happened circa 14,000,000,000 B.C.? Only if one presupposes a naturalistic origin/development of all things.

Evolution and the big bang are 2 peas in the same pod.

Pete D - #62813

June 22nd 2011

The Big Bang is one candidate model (and the best one) of the history of the universe. It originates from reversing the observed expansion of the universe as we move forward in time to a contraction as we go back in time. To deny the Big Bang you must deny the expansion of the universe or find another model that better fits the data.

The prediction of the CMB resulting from the Big Bang is a result of solving equations from the theory of relativity and was done 20+ years before the discovery of the CMB. The same scientists used the model to predict the relative distribution of H and He isotopes in the universe as well. They have since been measured and confirmed to match those predictions (although heavier elements are now known to have formed via stellar nucleosynthesis).

I guess you could say that Gamow et al. did not account for the possibility that a magic fairy could poof the whole thing into existence last Thursday, though. Maybe you could suggest how magic fairy-ology predicts the CMB? Or the cosmological redshift?

beaglelady - #62719

June 19th 2011

Sounds good to me, Pete.  Do you think that Genesis would only have value if was 100% historical and scientific? Do you take every part of the Bible literally?

Roger A. Sawtelle - #62727

June 19th 2011

Genesis is indeed about the Beginnings.  The Beginning of time and space.  The beginning of humanity and sin.  The beginning of human peoples and diversity.  Finally the beginning of the Jewish faith and the Chosen People.

The basic assumptions of sceince and philosophy are expressed in speculation and thought.  In the Bible they are expressed in a historical narrative.  The importance of this narrative is found in the ideas that it conveys, not its scientific accuracy.  Genesis lays down the theoretical foundation for science, it is not in itself a scientific description of the beginnings.

Genesis is the story of change.  Philosophy is the story of permanence.  Sceince has been the story of permanent natural laws.  Genesis is not myth, because myth is not rooted in history.  Genesis is logos, which gives rational form to history and reality from beyond history and reality. 

Jimpithecus - #62735

June 20th 2011

Roger, excellent summation.  The stories in early Genesis gave the Hebrews meaning.

Pete D - #62771

June 21st 2011

Why the need for stories rather than truth? If the Hebrews were not totally confused as to the existence of angels, demons, gods, devils, and supernatural forces then why would they be confused as to the existence of atoms and gravity?

Pete D - #62728

June 19th 2011

@beaglelady - I don’t think that the value of any piece of written text is dependent upon its historical or scientific accuracy. However, the whether or not the bible has value is irrelevant to whether or not its claims are true. My point above is that if we are to take as allegory or metaphor or narrative mythology those parts of the bible that are inconsistent with scientific knowledge instead of invoking divine intervention, then we must include the resurrection as well as the fantastical claims of superpowers possessed by other bible characters.

beaglelady - #62730

June 19th 2011

So you take everything in the Bible literally?

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