The Frequently Overlooked Geological Context of Hominid Fossils

The human fossil record is probably one of these least understood and talked about topics in the church.  I have neither the expertise or desire to stride into the debate over particular fossils and their merits as either representing human ancestors or not.  I understand that human origins is a sensitive topic especially within the conservative evangelical church today with the historicity of Adam and Eve playing a very important role in Christian doctrine.  I get all that and agree that it is very important.  What I am interested in is what happens as one moves beyond the biblical evidence for Adam and Eve and attempts to apply that doctrine to the actual physical creation and the history that is evident in it.   The simple statement that all humans are descendent from a historical Adam and Eve is easy to say and believe but the application of this idea takes on many many different faces especially when trying to put Adam and Eve in context with fossils, population genetics and human migration studies.   The reaction to the fossil record of  humans has been extremely variable even by those that ascribe to single pair (Adam and Eve) of progenitors in the recent past.  I am working on a review of a fascinating book I just finished entitled, “Adam’s Ancestors” by David Livingstone which looks at the views of primarily Christians over the past 2000 years regarding the origin of human races, human fossils, evidence of ancient human populations etc.. and shows that struggles with explaining human population distributions, race, variation and more recently fossils have been around far longer than just the past 100  years but stretch way back with many different views holding sway over time.

Malapa cave – early 2010 where the fossils that have been named Australopithecus sediba were found. Photo courtesy Lee R. Berger and the University of the Witwatersrand 2010. http://www.profleeberger.com/australopithecussedibaimages1.htm

If a recent past (10,000 years) Adam and Eve position is taken then this would require that all fossils be assigned to either descendants of Adam and Eve or the remnants of extinct lines of primates that, though they may have been similar to humans are not in the lineage of Adam and Eve and thus not human by definition.   But which fossils belong to which group? There is by no means a consensus among evangelicals with some saying that some fossils, for example, those ascribed to the name Homo habilis, are not human and others saying they are.  It isn’t just the physical features of the bones and their relation to humans that is debated but the associated evidence of culture that are found along with the bones that are hotly debated.

With this in mind, the Malapa caves of South Africa has made news again for the discovery of additional fossil hominid bones (additional story from National Geographic).  (I am using the term hominid since there is no consensus among Christians about their humanity).  This time CT-scans and X-ray technology have identified bones in solid rock that will require months if not years to extract. The bones previously found there already have been described as a new species,  Australopithecus sediba,  which has been promoted as one of the earliest ancestors of humans with evidence of walking upright including specialized hip and foot bones.  This particular fossil site has been widely discussed and debated among anthropologists because of the difficulty in understanding the mixture of characters in the skeleton (very small cranium and long arms, but hips and feet that suggest upright walking and possibly even able to run).   Young earth creationists, and even many old earth creationists such as Hugh Ross, don’t accept primate ancestry of Adam and Eve and so assign presumed human fossils to either being a descendant of Adam or an extinct species of ape.  The features of this particular set of fossils show how difficult it can be to determine if the bones are human or ape.   Todd Wood (young earth creationists) published an extensive review of hominid fossils in the Answers Research Journal which is Answers in Genesis’s so-called peer-reviewed advanced research journal,  in which he employed a variety of statistical measures to try to define the homo “baramin” (a barmin for YECS is the original created kind) versus non-human ape baramin.   He concluded that most of the fossils described by anthropologists as “Homo” are descendants of Adam and Eve. This would included Neanderthals from Europe, the hobbit fossil from Indonesia, Homo habilis,  Homo erectus etc…  He also concluded that the fossils from this site described as Australopithecus sebida is also a descendant of Adam but that other species of this genus represent extinct apes.   Hugh Ross (old earth creationists) is far more restrictive than Wood or even any other young earth creationists. He finds that Australopithecus sediba and even most of the other “homo” fossil species are not human. However, this is primarily because of the lack of cultural evidence associated with the fossils.  A year after Wood’s paper was published AIG published an article on this website by three of their staff that discussed how this fossil was nothing more than a extinct ape.  I find two things interesting about this second article.  1) The authors make NO mention of Wood’s extensive analysis of hominid fossils including the one they are specifically critiquing in their article thus giving their audience no idea that other creationists disagree with their view and 2) although they dispute the dating techniques used to show the fossils are around 1.9 million years old they do not discuss the geological context in which these fossils were found.

Fossil bearing rocks tagged and ready to depart for the lab at Malapa early 2010.  These rocks have been taken from the pit that represents the fossil cave system (called paleocaves) and represent a portion of the cave that was under a death trap opening and so have accumulated many many bones of animals.  Photo courtesy Lee R. Berger and the University of the Witwatersrand 2010. http://www.profleeberger.com/australopithecussedibaimages1.htm

Despite the emphasis of my long introduction, the debate over human ancestry isn’t what I am interested in commenting on with respect to this recent fossil find.  I’m really interested in the context of the fossil find here not the details of the fossils themselves.  If hominid fossils themselves are poorly understood by Christians then the geological context in which they are found is probably a complete mystery.   I think there are two reasons for this: 1) the geological context isn’t understood and so not explained  2) when it is understood by Christian apologists they find it so challenging that they don’t want to discuss it.  I will try to illustrate the problems with geological context by examining this Malapa cave fossil site that contains the bones what is either an fossilized extinct ape or a fossil human but whichever they are the geological problems raised by the site are the same.

Malapa Cave – South Africa

In a region just north of Johannesburg South Africa there is a network of cave systems.   Many hundreds of new caves have been discovered in the past 5 years and many contain fossilized bones.  Anyone that hears about these caves is probably picturing a series of caverns underground and remains in the sediments in these caves.  Yes there are still underground caves in the area but many, if not most of the caves including Malapa cave are actually remnants of caves not caves themselves.   Look at the first picture. There is simply a rocky depression where many fractured rocks have been removed.  But this is exactly where rocks with fossils of many animals and potentially humans has been found.

You maybe left wondering, how can this be called a cave?   As I just suggested, what you are looking at is the remains of what used to be a cave system.   Below is cartoon depicting what this area was like in the past when the caves system was still active and underground.  What we have left today in this area are hundreds of rocky deposits that represent the mineralized rock (flow-stone, stalactites and debris that fell into the cave and was cemented together) where cave pools and large rooms used to be.   As the cartoon depicts, a cave system is thought to have formed in these rock layers in the past but at the time the caves where 50-100 feet under the ground.  At times there were

Malapa Cave cartoon depicting what the caves system might have been like at the time that the animals and primates that fell into the cave and became fossilized by minerals in the water. Courtesy Lee R. Berger. Illustration by Paul Dirks.

cave-ins which creating sinkholes at the surface leading down to caverns underground.  Those sinkholes became death traps where animals running along the surface could stumble down the pits to their deaths at the bottom in a small lake or stream. There they would decay with no scavengers and their bones would eventually become encased in stone as more debris fell on them and became cemented by the minerals in the water.    The same could have happened to any human or ape living in the area. Maybe they attempted to climb down into the cave and slipped, or maybe they were thrown in, or they were chasing an antelope and just fell in.  However they fell into the cave they were probably killed on impact and preserved where they lay.   These “caves” today are identified by these hard rock outcrops that represent the hardened rocks of cavern lakes and pits that filled with material.   Over time the rock that lay above the cave gradually eroded to where the ground surface is today.   So for much of this area the caves now are exposed as the hard rocks that are left with the softer rock that the cave originally was made in is now gone.  Hundreds of these cave “deposits” have been examined.  Most have NO fossils in the preserved cave stone at all. This is probably because most of the cave system of pools never had an opening to the surface above them when the sediments and minerals formed to fill the space.  Only a few of these cave deposits have fossils but when they do they have a LOT of fossils and all of them represent species that are extinct today.  In some cases hundreds of different animals have been identified in one cave deposit as the sinkhole/death trap just continued to collect victims over time.

A photo showing the MH1 skull emerging from the rock. When they started working on this block they only knew about the humerus bone to the right but nearly the entire skull was embedded in this small rock.   You can see that these fossils are fully embedded in stone and so require huge efforts to remove.  Photo by Lee R. Berger. Additional images at: http://www.profleeberger.com/australopithecussedibaimages1.htm

The geological context is quite clear for these fossils.  They are found locally in abundance in rocks that are clearly of cave origin based on chemical composition.  The animals bones that are found show no sign of scavenging and so it appears that all died in place rather than being dragged to a common location.   Yet, all these fossils are found essentially at ground level or just a meter or two below ground level today.  Below is a map of a cross section of one of these filled in cave pit deposits in which the Australopithecus sediba fossils were found.   You can see these fossils were found just a couple meters below the general land surface. This rock is fractured and eroding now that it is exposed and they have pulled pieces of rock out of this pit and have been doing CT-scans to look for bones of primates.  The rocks are fulls of bones of other animals again indicating these are the remains of animals that have fallen into “death trap.”

A NE-SW cross-section sketch map through the Malapa site showing the Distribution of sedimentary facies, position of hominid fossils, and U-Pb and palaeomagnetic sample locations, together with U-Pb ages and normal and reversed polarities.  Note that A is soil and represents the current ground level.  Imagine Pit 1 as a cross section of what was a cave coming at your that has been filled in with material.  Courtesy Science Magazine/AAAS

Geological Context and Young Earth Views on Human Fossils.  

By now you have probably guessed why I have suggested that the geological context of these fossils is in many ways more challenging to explain than the fossil bones themselves.    Taking the the usual young earth worldview how might the presence of these bones be explained?  First, we have to ask when these fossils are predicted to have formed.  For the YEC, cave deposits are formed in rocks that lie upon even more layers of rocks that bear fossils and so all these rock must be explained as the result of a global flood.  As such, caves in rocks are post-flood phenomena and logically then any materials deposited inside a cave must represent materials that came to be there after the flood.   So right away this puts all of these fossils as having been formed after the flood.   But how long after the flood?  If the fossils of A. sibida do represent descendants of Adam and Eve as a few creationists believe then that puts their origin even later since the same creationists believe that all people were congregated at the tower of Babel several hundred years after the flood and then dispersed across the globe.   So, the caves would have formed in these rocks after the flood and then people (albeit, a very long armed small brained version of human) made there way all the way down to the tip of Africa and a few fell into these caves and were preserved.  After that the land eroded many 10s of feet but probably 100 feet to expose the then no longer active caves (there is another cave system now in even deeper layers below these “fossil” caves at the surface).

I think it should be obvious that this scenario stretches credulity.  How can so much rock erode over a few thousand years with no obvious means of erosion other than rainfall and some wind?   You might be tempted to suggest the past climate was radically different but that can be tested by the deposits themselves.  Pollen, spores and other plant material blown into the death pits have left a columnar record of past climate from bottom of the pit to the top of the pit.  A very thorough examination of this material reveals that the climate of this region has remained very similar (the same plants lived in the area) over the lifetime of the pits filling.   So no massive erosion events seem to be available to explore the erosion of millions of tons of rock of this huge area where hundreds of old caves are now exposed.   The conventionally dating of this pit is that it was a cave with an active water system a bit over 2 million years ago and then became filled several hundred thousand years later and been sitting there since then while the land eroded above to expose these remains.   For YECs, there are only 4000 years to fit the development of the cave, the pit formation and the filling of the cave with remains, solidifying into rock and then erosion of the top layers of rock.

I would suggest that the geological scenario that I have presented is why the geological context of these fossil finds is rarely reported in the creationist literature.  With respect to other Australopithecus species found in same area in other ancient fossil caves I sometimes see that they are reported to come from caves or even from death pit deposits but until I researched this site myself I had no idea that the rocks that many of these fossils were found in were just sitting practically at the surface and yet were from cave deposits.   I certainly never would have gotten this impression from any creationist literature.

Now, many who have read this far may be thinking that this doesn’t really matter much because they don’t believe that the fossils found in these cave deposits are either human ancestors or descendants but just an extinct ape.  While this might help remove these fossils from having to fit them into an Adam and Eve scenario I don’t think that suddenly makes these fossils a non-issue.  I say that because no matter whose bones are found in these rocks the fact is there are bones found in cave deposits that are still a post-flood deposit according to young earth creationists.   As a result their very presence raises the same questions about the age of these rocks.   Animals still had to make their way from the Ark down to southern Africa. Hundreds of them had to fall in this hole which in itself likely happened over thousands of years rather than short period of time.   The cave system then had to fill with debris and then the rock over the cave had to completely erode to expose the rocks that encase the fossils.   All of this still had to happen in less than 4000 years so human or not the challenge is still the same.  The issue with the geology of these sites is therefore less about human origins than it is that these sites speak to the age of the earth.

Conclusion:

The geological context of fossils adds another degree of complexity to the interpretation of these fossils.  I am not certain how to explain the fossils themselves in context with the Biblical record if the world were young or old but  I do know that within a young earth context where flood geology is used to explain present day geological phenomena the presence of fossils in these rocks is a serious problem.  The YEC literature expends a lot of page space to explaining away the intermediate features of these fossils and while that effort is not especially convincing their geological timeline for a fossil site such as Malapa is so far-fetched that ignoring the context of the fossil  finds seems to be the only response.  I have only provided one example of how the context of the fossils presents challenges to a young earth interpretation of the fossils.  There are other famous fossils that I think all evangelicals would claim as human because of the types of cultural items found along with them but for which the geological context is just as challenging.   All too often we are presented with fossils extracted from their historical context and displayed in museums and articles.   Context is important because it speaks of the history of the fossils.  As a Christian I don’t feel like I should be scared of the history and shielded from it even if I don’t fully understand it.

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Comments

  1. ashley haworth-roberts says:

    AiG appear to assume that anything in the genus Homo was really ‘human’ and descended from Adam. Whereas A sediba (and A afarensis – depicted as ‘some sort of’ knuckle-walking gorilla’ in the Creation Museum) were just apes.
    Although the latter species appears to have been able to fashion tools – several millions of years ago: http://www.nature.com/nature/journal/v466/n7308/abs/nature09248.html

    “I would suggest that the geological scenario that I have presented is why the geological context of these fossil finds is rarely reported in the creationist literature.” “Until I researched this site myself I had no idea that the rocks that many of these fossils were found in were just sitting practically at the surface and yet were from cave deposits. I certainly never would have gotten this impression from any creationist literature.” I think that is a fair assumption and a revealing comment. Also, by YEC ‘history’, one might expect to find fossils of non extinct species in some of the cave remains in this part of South Africa (though mainstream scientists believe that 99% of species have gone extinct I think).

    “The issue with the geology of these sites is therefore less about human origins than it is that these sites speak to the age of the earth.” No wonder Ken Ham hates ‘millions of years’ so much. Any open-minded Christians knows that while it is difficult to reconcile with the Bible, the Old Earth paradigm is abundantly supported by scientific knowledge and observation.

    As you say, context is important in science.

  2. “For the YEC, cave deposits are formed in rocks that lie upon even more layers of rocks that bear fossils and so all these rock must be explained as the result of a global flood. As such, caves in rocks are post-flood phenomena and logically then any materials deposited inside a cave must represent materials that came to be there after the flood. So right away this puts all of these fossils as having been formed after the flood.”

    NH, not all YEC geologists posit post-flood cave formation, e.g., Emil Silvestru’s article on karst formation in “Rock Solid Answers” (2009), and Jerry Akridge’s article in the Fall 2010 CRSQ on Sequoyah Caverns, AL.

    As a YEC myself, I appreciate your thoughtful commentary and questioning. We won’t know the whole truth till we get to heaven, but in the meantime, I believe that honest and respectful discourse is one of the better ways to build up the Body of Christ in the face of division.

    • Hi S.J. Thanks for your comment. I apologize for the delay responding. I have read several of Silvestru’s articles and while he may have a point about some caverns I don’t believe his argument will translate to many of the caves that harbor human remains. Your point is taken though that not all YECs find all caves to be of post-flood origin.

      • when the author quotes works of such charlatans and plagiarizers as Wood he looses total credibility with the scientific community. If you are to convince those who believe the bible is written fact as opposed to writings that must be interpreted, you need unadulterated science to be convincing. Wood’s interpretations are more or less religion, since the reader has to believe it is true and can not test the facts for him or herself.

  3. klasiekraalogies says:

    Excellent work, NH! I lived quite close to this area for a number of years (but never visited it, I’m still kicking myself!).

    The larger geological context is also quite fascinating. Over a stretch of maybe 60km you would from the Witwatersrand Supergroup, an Archean deltaic succession that hosts the worlds richest gold deposits, through the Transvaal Supergroup – the lower TSG contains the carbonates hosting these caves, while the upper TSG contains more clastic sediments (incidentally, the TSG also contains some of the earliest record of life, beautiful stromatolites), and then, once you cross the main Magalies range, which sits at a dip of about 30 degrees, you find yourself on the Bushveld complex – a massive intrusive complex containing some of the richest Platinum Group deposits. The Bushveld intruded at about 2 Ga. And to cap it off, about 100km or so over the plains that define the Bushveld, you get the massive Pilansberg complex, an extrusive alkaline complex (mainly syenite), one of the largest in the world, which last erupted ca. 1.2 Ga ago.

    Yes, this is where I learnt my geology, and I count myself privileged.

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