Optical Illusions: The Challenge of Tracing Human Origins

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If tracing this lineage from our earliest ancestor seems inconsistent or spotty, that’s because it is. We have a makeshift model of human history that had been cobbled together by geneticists, archaeologists, anthropologists and biologists. Finding common ground and an overall consensus among these different disciplines makes finding the truth even harder. Looking back at human history is an optical illusion; new archaeological discoveries are always challenging what we already know, and constant revisions are being made.

In 2013, a major find would cause further controversy within the already complex grouping of hominids. In Dmanisi, Georgia, an archaeological dig was under way. After finding a series of four similar-looking skills during the dig, the fifth one looked irregular. This skull had a small braincase, large teeth and a powerful jaw, but judging by the skull’s shape and structure, it must have been attached to a long-limbed, human-like body, not a short-limbed, muscular body like Australopithecus. An apelike skull attached to a human body are features that never co-existed prior to this discovery. This has led scientists to believe that the Homo Subspecies of Ergaster, Erectus, Rudolfensis, Habilis and so forth, may have actually been one species that simply looked different - much like the varying appearances of different races we encounter today. This find has been known as “Skull 5”, and has already caused a debate about how the homo species should be classified. This finding will spawn a debate until a newer find is unearthed and new data is presented. These revisions will continue until we either run out of fossils or more advanced technology allows us to shed light on this ongoing mystery.

The Dmanisi early Homo cranium

The Dmanisi early Homo cranium, ‘Skull 5’. Photo courtesy of Georgian National Museum

The scientific dating of species that have been found is volatile by nature. Lucy, the Australopithecus specimen went through several date revisions since she was found. Anthropologist Susan Martinez outlines the numerous times Lucy has been re-dated to fit with contemporary theories. In the 1950’s following Lucy’s discovery, she was estimated to be at least 500,000 years old. This number changed in the 1970’s to at least a million years old. After new discoveries in Ethiopia, that number jumped to two million. The wide estimates between these broad and sweeping figures are known as scatter in archaeological terms. A species known as Petralona Man is said to have existed between 70,000 to 700,000 years ago. Another known as Morocco Man was first estimated to be 40,000 years old, until further tests actually placed him at 125,000 years old. The prevalence of scatter across these finds makes it no wonder why our lineage is so difficult to trace. How is it that these figures come to be so slippery and hard to pin on a timeline?

The skeletal remains of ‘Lucy

The skeletal remains of ‘Lucy’ (Australopithecus). Image source: Wikipedia

The techniques used to calculate the date of a fossil aren’t perfect and are subject to error. A technique known as radiocarbon dating works by measuring how levels of carbon have dropped in a bone fragment or artifact over time. Exposure from the sun on a piece of bone, for example, accumulates nitrogen in the bone fragment. This nitrogen turns into carbon-14, which acts as a measuring guide for how old an object is. Over time, carbon-14 levels decrease – these levels serve as a yardstick for the age of the object. This technique is most accurate up to a period of 60,000 years – anything longer and results are often unreliable. The level of carbon decay may have varied across different time periods in the past. Some species may have had less exposure to sun, or climate change may have influenced the amount of carbon in the atmosphere. The higher the fossil is in the surface of the Earth, the more likely it comes into contact with weather, animals and other agents. Even exposure to coal can contaminate the carbon levels in a finding, yielding highly different results. A finding in France known as the Fontechevade Man has been estimated to be between 40,000 to 800,000 years old just based on readings of nitrogen levels alone. Scientists have even resorted to using different levels of dating to counterbalance the levels of scatter that may occur from carbon dating.

One technique known as faunal dating looks at the animal remains of species that may have existed millions of years ago. Traces of these species can let us know how old an object is, but can yield confusing results. Susan Martinez offers a good example: We have estimated Trilobytes (an ancient crab-like species) to have existed at least 550 million years ago – the Cambrian era. But any finding with traces of Trilobytes is said to be from the Cambrian era. How do we know Trilobytes are 550 million years old? Because Trilobytes existed 550 million years ago. This argument goes in circles and explains why a technique like faunal dating is unreliable in reading human fossils we encounter. We use fossils to date rocks, or rocks to date fossils – we are left with only relative dates of which species lived when. These are problems that arise when trying to date these fossil finds. Each new find re-writes history, which is written again, further confusing our already obscure and complicated origins.

Comments

Tsurugi's picture

Excellent article that poses penetrating questions amidst well-chosen examples of anomalous evidence. I had never heard of Moab Man before reading this. Fascinating!

My only problem is with the explanation of the formation of C14. Are you certain that is the correct explanation...? I thought C14 was a cosmogenic nuclide...an unstable carbon atom with a "heavy" nucleus due to high-energy particle collisions in the upper atmosphere caused by infalling cosmic ray particles.
The theoretical underpinning of cosmogenic nuclide dating techniques--including C14 dating--is of special interest to me. As such, I have written somewhat extensively on this subject before. If the description given in this (otherwise excellent) article is correct, I have some serious corrections and apologies to make, lol....

DeAegean's picture

The green bones really surprised me.. I want green bones when we are all ancient history.

Roberto Peron's picture
Everything is Anthropology is "provisional" meaning everything is subject to change and this is espeically true when it come to human origins and human evolution.  For scientists to assume that there was little to no individual variation within a species is shortsighted at best.  Of course there were individual differences in past human species just as we see individual variations in our own species (Homo sapiens) today.  Personally, I think genetic sequencing will solve the problem when it comes to humanity's past.  It has already turned some things upside down such as revealing that 3% of the DNA in people of non-African origins is Neandethal DNA.  Neanderthal didn't go extinct.  They simply inbred with modern humans and were assimilated into the H. sapien species.     As for Lucy?  She was indeed of the Australopithecus species and that species was the true "ape men."  Martinez is correct as, in fact, Lucy has been redated many times, yes, to fit into our nice little theories!  Problem is true SCIENCE is suppose to follow the evidence WHEREVER it might lead and not the other way around!!  Trying to force something to fit one's pet theory is NOT science at all but wishful thinking.   "How is it that these figures come to be so slippery and hard to pin on a timeline?"  It's because there is something fundamentally wrong with our dating techniques I postulate.  And further, I think some of the fossils we have found and attributed to humans are actually fossils of ancient apes and not human at all.  But that's another subject for discussion later perhaps.   Everyone needs to note that Carbon 14 dating is accurate up to a period of 60,000 years and, as this article states, ANYTHING LONGER then the results are "OFTEN UNRELIABLE."  That is a key point to remember when considering the alleged ages of these fossils.  Beyond 60K years and it is guessing!  Another key point to remember is the, as this article says, "climate change may have influenced the amount of carbon in the atmosphere."  Most certainly it did and the histroy of the Earth is riddled with MANY changes in climate.     Moab man doesn't fit the presently accepted academic theory of human origins just as Kenewick Man doesn't.  Note Kennewick Man was found in Washington  State USA and looks a lot like actor Patrick Stewart.  He was Caucasian not Native American.  When something doesn't fit the accepted view then you re-bury it or hide it and ignore it hoping no one will notice.  And if they do?  Ridicule and marginalize them without mercy!  Sadly, that seems to be the unwritten rule of science today.     Suffice it to say human evolution is in a constant muddy state due to new finds, contrary finds, out of place finds, inaccurate dating techniques, pet theories, untrue hypotheses, and a host of other reasons.  So, then, how are we suppose to know about our own origins?  I think the answer may be that we are NOT!  Someone doesn't want us to know the truth behind human origins, yet it comes out anyway on sites like Ancient Origins and others.    

I think anthropologists today are simply racists. If, for some reason, anthropoligists in 20 000 years still had the same mindset as today, facing the enormous diversity of modern man today in their fossil record, they would also start forming fantastic theories of different human species interbreeding and what-not.

Homo erectus is the first real human, and all the others after that, that were most definetly bipedal (unlike australopithecus and homo habilis who were more probaly still quadrupeds), are just members of our own species. They are races, changing over time just as we are seeing happening today, nothing special about it. Would you call Australian aborigines or pygmys a different species? Go ahead, do it in publc, I can't wait.     I think we could construct an experiment on these lines that would end in them saying something like that. It would be lovely:)

I have a feeling that all this scientific interest in these imagined species of theirs is just a decoy to take attention off the real issue: What is the exact nature of the relationship beetween these early hominids, Homo itself, and the chimpanzee which is gennetically soo close to us?

Please research Macroevolution.net.

Hybridization can explain the history of the evoution of organisms much more consistently than neo-Darwinism. Early hominids could be intermediate hybrids; of what? You'll have to read it. 

 

Memento mori :D

As I recall Moab man has been carbon dated to between 210 and 1450 years before present, and is likely the result of burial. It would make sense as the tribes living in the region at the time did interment burials.

The article states, "Would we not have to rewrite our entire understanding of human origins, stating that humans were at once anatomically modern, before devolving into Neandertals only to re-emerge as homo sapiens?"

To me, that makes more sense.  We know that humans, neanderthal, and denovisans could interbreed, which makes them the same species by definition, differing in phenotypic appearance.  

If, as many geneticists argue, a human bottleneck occurred tens of thousands of years ago, leaving only a few thousand breeding humans and leading to mutations, I think we today have survived as the mutations of these survivors.

The theory of punctuated evolution relies on mutations.

 

Tom Carberry

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