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Lucy: walking tall—or wandering in circles?

by , CMI–Australia

22 July 2005

Did the famous ‘Lucy’ (Australopithecus afarensis) walk truly upright? That has long been a bone of contention, even among evolutionists.

Of course, walking upright would hardly prove that Lucy was an ancestor of humans—but it would add some ‘icing on the cake’ to such a claim.

Now a computer model published in the Royal Society’s Interface journal1 is said to support the idea that Lucy did walk upright, judging by the most energy-efficient gait. The model was based on a combination of afarensis skeletal features and the famous footprints in volcanic ash at Laetoli. To help assess these claims, some background facts need to be kept in mind.

  • Detailed anatomical analysis has long suggested that Lucy’s kind did not walk upright. Respected anatomists like Dr Charles Oxnard (evolutionist and holder of professorships at the University of Western Australia and the University of California at Santa Barbara) have concluded from a detailed multivariate computer analysis of the bones that Lucy’s kind (australopithecines)

    a) did not walk upright in the human manner and

    b) were in their overall anatomy not intermediate between apes and humans.2

  • Lucy was equipped for knucklewalking. Well after her discovery, it was shown that Lucy had the wrist-locking mechanism of knuckle-walkers, as well as the long arms, (and curved fingers and toes) of brachiators (creatures that swing through trees). Of course with ‘special pleading’ one could argue that the wrist mechanism was an evolutionary ‘left-over’. So not surprisingly, that is what the ‘Lucy walked’ faction have argued. But the presence of this mechanism doesn’t sit comfortably with a belief in upright walking—creationists and evolutionists should agree that useless structures, without any selective advantage, will be quickly ‘lost’ by mutation.3

  • Lucy’s kind had the wrong balance organs for upright walking. As discussed in the video Image of God, evolutionists have performed CT scans of the skulls of several apeman candidates to assess upright walking claims. (The angles in the semi-circular canals housing the organ of balance are very sensitive indicators of locomotive abilities.) All of the specimens in the same general grouping as Lucy were shown to have moved in an apelike fashion, neither human nor even ‘intermediate’.

  • The famous Laetoli prints were probably not made by ‘Lucy’s kind’. Since their discovery, the well-known Laetoli footprints (in volcanic ash) have long been acknowledged by all camps as having been made by two upright-walking individuals. The prints are ‘dated’ at some 3.5 million years, long before humans are supposed to have been around on the long-ager’s time scale. So by evolutionary reasoning, they would have to be from man’s ancestors. Thus, because A. afarensis was believed to have been the human ancestor in the neighbourhood at that point in evolutionary time, afarensis becomes the author of the footprints, by ‘default’.

    The prints, unlike the feet of chimps and Australopithecus africanus, have the big toe in line with the foot. Tim White, perhaps the leading authority on the subject, was quoted in a book by fellow evolutionary apeman researchers as saying:

    ‘Make no mistake about it, they are like modern human footprints. If one were left in the sand of a California beach today, and a four-year-old were asked what it was, he would instantly say that someone had walked there. He wouldn’t be able to tell it from a hundred other prints on the beach, nor would you. The external morphology is the same. There is a well-shaped modern heel with a strong arch and a good ball of the foot in front of it. The big toe is straight in line. It doesn’t stick out to the side like an ape toe, or like the big toe in so many drawings you see of Australopithecines in books.’4

    An evolutionist from the University of Chicago, Russell Tuttle, has said:

    ‘In discernible features, the Laetoli G prints are indistinguishable from those of habitually barefoot Homo sapiens.’5

    However, to conclude that humans made them would be ‘ruled out of order’ by the dating! Dr Tuttle compared them to the footbones of the ‘Hadar hominid’, classed as A. afarensis, and claimed that this would rule out afarensis as the makers of the tracks (he postulated some other ‘derived hominid’).6

    Others have disputed Tuttle’s conclusion that the tracks were not made by afarensis, with the earlier-quoted Tim White still claiming that Lucy’s kind was the best candidate.7>  It is clear, though, that with so much controversy raging, it would be premature, to say the least, for an evolutionist to ‘hang their hat’ on the Laetoli prints being made by Lucy/afarensis types. Even the British Museum’s human evolution expert, the well-known Chris Stringer, says in the same BBC news item that announced the study:

    ‘There are still some people that argue that, looking at the anatomy of the foot bones of afarensis, that they were unlikely to have made the Laetoli footprints. So [this study] doesn’t end the argument because there is still the possibility that there were different creatures around at the time.’

    Indeed. Namely humans.

Round and round the logic goes …

Which brings us back full circle to the study we are commenting on, alleging to show that Lucy walked upright. In assessing any computer modeling, we need to remember that computers can only deal with the data in the form it is presented, including all the assumptions. (A less charitable, but no less accurate, way of putting it is ‘garbage in, garbage out’.)

The study in question uses reasonable assumptions (though limited by being only a two-dimensional analysis) to do with energy costs of locomotion, checked against human volunteers. However, it clearly involves a degree of circular reasoning. It assumes (on the basis of other studies by other authors) that afarensis walked upright. And it also assumes that the (definite, undisputed) upright walkers at Laetoli were Lucy’s kind. As one of the study’s co-authors, Weijie Wang from Dundee University, is quoted as saying in the BBC report:

Assuming that the early human relative Australopithecus afarensis was the maker of the Laetoli footprint trails, our study suggests … [that afarensis] could sustain efficient bipedal walking at absolute speeds within the range shown by modern humans.’ [bold emphases added]

To a more overt degree than is usual, this study’s conclusions depend on the validity of its starting assumption.  

Points in summary

  • Whether Lucy walked upright or not does not alter the reasonableness of the conclusion that she and her kind were not ancestral to humans. However:

  • Evolutionists generally like to think that Lucy did walk upright, to lend support to the markedly weak case for ‘ape-men’. 

  • There has for some time been good evidence that Lucy did not walk upright.

  • The Laetoli prints were definitely made by upright walkers.

  • There is so far no published reason (apart from long-age/evolutionary dating assumptions) to disbelieve the conclusion that the Laetoli tracks were made by barefoot humans.

  • Evolutionists are generally ‘shoehorned’ by their belief system into assuming that the Laetoli prints were made by Lucy’s kind.

  • The recent study on energy efficiency of locomotion for afarensis lends some limited support to the possibility of Lucy walking upright, though this is only given their assumptions. But this needs to be weighed against the much greater amount of evidence which supports the opposite conclusion, especially given the acknowledged limitations of the computer model and the (less acknowledged) weaknesses in the reconstructions available. And the waters are muddied considerably by circular reasoning, especially (but not only) where it applies to the Laetoli footprints. In the paper’s own words (bold emphases added):

    ‘This study therefore applies forwards dynamic analysis and genetic algorithm optimization to reconstruct the metabolic costs associated with different stride lengths and speeds for A. afarensis, on the assumption that this species walked upright, following Nagano et al. (2005) and go on to apply our results to interpretation of the Laetoli footprint trails, assuming again that A. afarensis was the maker.’

    (Note how both assumptions are really about the same thing. Because if it is assumed that afarensis made the tracks, then since the tracks are undisputedly those of an upright walker, that again assumes that afarensis walked upright.)

    So for media reports to imply that this study demonstrates that Lucy/afarensis walked upright begs the question: how can this be so if the study itself states that it assumed that afarensis walked upright?

The late creationist pioneer, the triple-doctorate Professor A.E. Wilder-Smith, once commented in a documentary, in his inimitable style, on circular reasoning by evolutionists in another context. He noted dryly that such circular reasoning (if it is being implied that the statements have explanatory value) is ‘not exactly the highest form of logic’. I agree.8

References and notes

  1. Sellers, W., Cain, M., and Wang, W., and Crompton, R., Stride lengths, speed and energy costs in walking of Australopithecus afarensis: using evolutionary robotics to predict locomotion of early human ancestors, J. R. Soc. Interface, doi:10.1098/rsif.2005.0060, published online. The report announcing this was found at news.bbc.co.uk/1/hi/sci/tech/4697977.stm, 20 July 2005. Return to text.
  2. For this and other references, see New evidence: Lucy was a knuckle-walker, Lucy isn’t the Missing Link and Oard, M., Did Lucy walk upright?, Journal of Creation 15(2):9–10, 2001. Return to text.
  3. See first link given in reference 2. Return to text.
  4. Johanson, Donald C. and Edey, Maitland A., Lucy: The Beginnings of Humankind, Penguin, London, p. 250, 1981. Return to text.
  5. Russell H. Tuttle, The Pattern of Little Feet, American Journal of Physical Anthropology, Vol. 78, No. 2, p. 316, February 1989. Return to text.
  6. The Lucy skeleton itself had no footbones, and one candidate for the Laetoli trackmakers was what could perhaps be dubbed the ‘Piltdown foot’—a composite foot made from combining the footbones of the Hadar hominid with those of another specimen allegedly from another species and separated by an alleged one million years. Return to text.
  7. White, T.D. and Suwa, G., Hominid footprints at Laetoli: facts and interpretations, Am. J. Phys. Anthropol., 72(4):485–514, 1987. Return to text.
  8. Of course, circular reasoning does not mean that the statements themselves are wrong, only that they can’t be used to support a case.  E.g. ‘The sky appears blue because blue is the colour that our eyes perceive it to be’. All true, but it cannot be used to explain the colour of the sky. Return to text.