The Changing Face of Evolution

The Changing Face of Human Evolution

(from an article published by Koinonia House)

We are told that science is always changing.  New information comes on the scene, and scientists work to figure out how that information fits in – or doesn’t – to current theories and explanations.  No field of science, however, appears to evolve as constantly as that of paleoanthropology – the study of ancient man and the apes that allegedly contributed to man’s evolution.  Most recently, a very interesting and ‘old’ skull was discovered in the African country of Chad, and has successfully turned the entire past 70 years of study of human evolution on its head.

The skull of this widely publicized new find, Sahelanthropus tchadensis, nicknamed Toumaï, has caused considerable ripples in the scientific community for a number of reasons;

  • Based on the relative age of the fossil record in which Toumaï was discovered, he has been dated at about 6-7 million years of age, several million years older than other ape skulls that have been considered as human ancestors.  This would be the time, according to current evolutionary theory, when we might find an ancestor that was not too far separated from the chimpanzees.
  • While his brain case is about the size of a chimpanzee, and while he looks like a chimp from the back, his face is flatter and his canine teeth are smaller – which are considered hominid traits.  At the same time, he has huge, gorilla-like brow ridges.  This is a strange mixture of  ‘primitive’ and ‘advanced’ characteristics.
  • Toumaï was found in the rough desert of Chad in central Africa, nearly a thousand miles west of the Rift Valley that has produced most of the ape skeletons that have been considered human ancestors.

Sahelanthropus tchadensis is indeed a remarkable find for the paleoanthropologists, but for an odd reason; he tells the scientists that human evolution is not as neat and tidy as they had assumed forty years ago. "A find like this does make us question the trees people have built up of human evolution," said Chris Stringer of the Natural History Museum, London.  Toumaï has been given an age at least 3 million years older than popular human-ape links like the australopithecines such as Lucy.  However, some of Toumaï’s facial characteristics are more advanced than Lucy’s. If a younger skull looks more ape-like than an older skull, that causes problems in considering the younger fossil a possible human ancestor.  Toumaï is forcing the scientists to reconsider simplistic explanations concerning human evolution.

Anthropologist Bernard Wood of George Washington University in Washington DC noted, "When I went to medical school in 1963, human evolution looked like a ladder."    In the old models, apes evolved neatly, step by step, into humans.  However, now he sees human evolution looking more like a bush – a bush with many dead ends.  While scientists have seen "human-like" characteristics in a number of ape fossils, they are now having to debate if and how those individual apes even relate to each other.  It becomes a game of mixing and matching.  According to Wood, the lesson to learn is that evolutionary relationships cannot be based on appearances alone.

In fact, it can be difficult to determine specifics about a creature based on pieces of a skeleton. Scientists have made the following uncertain descriptions regarding this newly discovered skull.

  • Toumaï is likely a male, because of his heavy brow ridges, but he could also have been a female.
  • Toumaï could be a direct ancestor, or could be from a side branch.
  • The place where his spine enters his head does not prove he walked upright, but allows that he could have.
  • He could be a hominid ancestor or a chimp ancestor… Or neither.
  • "I’m willing to bet some money that this is a hominid." – Daniel Lieberman Harvard University

Regarding the true nature of Toumaï, Wood says, "My guess is that it’s neither a chimp nor a human ancestor – it’s a creature that was living at the same time."

The difficulty with all these speculations regarding human evolution is that these paleoanthropologists begin with the a priori belief that humans did indeed evolve from apes.  From there, the scientists try to work every new skull into the belief system they already hold.  If, like Sahelanthropus tchadensis, the skull doesn’t fit into the normal mold, they are willing to change their views on how human evolution happened.  However, few ever ask the question, "Did humans evolve from apes at all?"

In spite of the growing confusion regarding human evolution, scientists are confident that further fossil discoveries will fill in the missing pieces of the puzzle.  We will not be surprised, however, if the puzzle continues to grow more disjointed and creates even more questions than it answers.  After all, science is always changing, but the Word of the Lord endures forever (1Peter 1:25).  

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