Reexamined Laetoli Footprints Confound Anthropologists

Second set of human footprints at Laetoli reexamined:
Do we have to rewrite the textbooks yet again?

by Jerry Bergman, PhD

Introduction to the Laetoli Prints

The well-known bipedal trackway discovered in 1978 by Peter Jones and Philip Leakey at Laetoli site G, dated 3.66 million years, “are widely accepted as the oldest unequivocal evidence of obligate bipedalism in the human lineage.”

The problem with this claim was discussed in my previous post.[1] Another trackway, less well known, had been discovered two years earlier at a nearby location called site A. It was partially excavated and the tracks were attributed by some to be those of hominins. The resemblance of the tracks with bear (ursid) tracks has marginalized its importance in the paleoanthropological community.[2]

A new paper reviewed here reexamined the footprints at site A (see Figure 1 for a photo of the tracks). The reexamination was motivated by a concern that the matrix infill of the prints was never fully removed, distorting the results. Assuming that the matrix infill removal has now been done properly, a new conclusion was reached. In brief, the scientists claim that “at least two differently bipedal hominins roamed eastern Africa.”[3]

The Importance of the New Analysis

The Nature article includes a discussion of the importance of the footprints. It emphasizes the fact that  the “human version of walking on two legs, known as striding bipedalism, is unique among mammals. It requires the ability to balance a tower of loosely connected body parts over a single foot, as the other foot swings forwards to complete the stride.”[4] Because obligate bipedalism is the normal means of human movement on land, evolutionists have attempted to bridge this mode of travel with that used by our assumed evolutionary ancestors. Furthermore, the belief by evolutionists in general was

this ungainly form of locomotion had a single evolutionary origin in an ancestral hominin, followed by about six million years during which further anatomical adjustments accumulated — a linear model of evolution in which early hominin bipedalism became progressively more similar to our own over time.[5]

This old view has now been challenged by new research. Paleoanthropologists feel that the reexamined fossils “show that multiple versions of bipedalism existed simultaneously during one or more periods of hominin evolution. … evidence of locomotor diversity in hominins has been overlooked for many decades.”

Essentially, judgments are being made on the basis of fossil fragments, which are often in poor condition, of skulls, jaws, teeth, and now, footprints! No wonder confusion exists. For example, in this latest study, the researchers compared the footprints at site A with those of American black bears, chimpanzees, and humans. The bear data was obtained by measuring 46 footprints from four bipedally walking, wild, juvenile, black bears. They were chosen because their foot lengths were within ten percent of the length of the site-A footprints.[6]

Then the researchers measured footprints of chimpanzees produced during both quadrupedal and bipedal modes of locomotion. Given the large sample size and the method used to obtain the data, these results were likely accurate. The comparison indicated to the scientists that the site-A footprints (out of which only one was usable) resembled those of hominins more than ursids.[7] This conclusion provides us with almost no information about the life-form that made the prints even though, from the footprint information, an entirely new species was postulated.

The re-examination is problematic for several reasons including the fact that

foot bones and footprints are not conventionally used to define species. A number of species names are directly attached to skulls, jaws and teeth from middle Pliocene sites in eastern Africa, but researchers have questioned whether some or all of these fossils are distinct enough from A. afarensis to be considered different species…. The state of the current fossil record ensures that this debate will continue for years to come.”[8]

The prints at site A will now be reviewed.

Problems with the Reexamination

Examination of the print in the illustration from site A published in the McNutt paper shows only one print, labeled A3. At best, it slightly resembles a hominin footprint. One other print, labeled A2, slightly resembles print A3. It is very tenuous to make a judgment based on one sample. This is one reason why new research in the area of human evolution often forces the so-called rewriting of the textbooks.

The announcements were based on what the researchers concluded was a foot impression that was “decidedly hominin-like with wide heel impressions relative to forefoot width.” This contrasts with footprints of chimpanzees and bears which have comparatively narrow heels.[9]

From this finding the researchers decided that the footprint was not made by Australopithecus afarensis (i.e., the Lucy species). This is a reasonable conjecture when the two prints are compared (see Figure 2). The other announcement, that “site A footprints were made by a bipedal hominin with a distinct and presumably more primitive foot than A. afarensis” is far more problematic.

There exist many other possibilities of the identity of the subject that made the footprints, including the possibility that the usable impression was not a footprint at all. It could be an indentation caused by random factors, as is true of the many depressions located near the print. Another possibility is, it was made by a deformed human such as one suffering from hammertoe, or a person with a genetically deformed foot, or a foot injured in an accident. Another possibility is the person who made the print was wearing some type of foot protection such as a sandal or a loose sole covering.

It is also significant that this article, as well as others like it, although based on, at best, very slim evidence, was published in the world’s leading science magazine. This illustrates how any scrap of evidence that might support a story of human evolution, no matter how tenuous, is acceptable in the most prestigious science journals.

Other scholars have criticized the McNutt et al. paper for arriving at unsupported conclusions. Professor of Geographical Sciences at Bournemouth University, Matthew Robert Bennett, and Principal Academic in Hominin Palaeoecology, Sally Christine Reynolds, also at Bournemouth University, declared  “we should be cautious about new fossil footprint findings” because, they correctly observe, it is a very

significant leap to identify a second species based on a handful of poorly defined tracks. Variation in trackways is the key issue here. Imagine going for a walk down a beach or sandy path. The footprints you make will vary from one step to the next. This reflects natural variability in human gait, as well as subtle differences in the characteristics of the ground you’re walking on.”[10]

Another major problem the Bournemouth professors observed is

a minimum of between ten and 20 footprints [is required] before you can confidently quantify the variability in just one dimension, such as footprint length, let alone several. Others have suggested that you may need over 250 tracks to adequately quantify the three-dimensional form of a footprint. Footfall and the resulting footprints are more variable than once thought and some have argued that even individuals of the same species may have highly unique gaits.[11]

A sample of only one usable print tells us next to nothing about the footprints’ maker. Yet the lead author of the Nature report, McNutt, concluded the prints belong not to A. afarensis but “it is certainly Australopithecus or something very like it.”[12]

Conclusions

The announcements made by McNutt et al. are based on evidence that is slim and problematic. They make a specious claim that footprint A3 documents that “multiple species of hominins co-existed there 3.7 million years ago.”[13] The conclusions deduced from the A3 footprint remind me of the notorious “face on Mars” which, when illuminated from a different angle at higher resolution, shows just an odd-shaped mesa (see Figure 3). In that episode, higher resolution photography revealed that the “face” was not what it first appeared to be.

Unfortunately, with the footprint A3, the careless researchers did not even consider any other possibility other than that the footprint belonged to some primitive, pre-human ancestor. Note the confidence of one evolutionist at Dartmouth University who bought into this view:

“we now have conclusive evidence from the site A footprints that there were different hominin species walking bipedally on this landscape but in different ways on different feet,” says DeSilva, who focuses on the origins and evolution of human walking. “We’ve had this evidence since 1976. It just took the rediscovery of these wonderful footprints and a more detailed analysis to get us here.”[14]

Another example of careless thinking is that footprint A3 was made by an unknown human ancestor who walked funny and lived in the same place and at the same general time as the Lucy ancestor in Tanzania.[15] Is it not an enormous blunder to take one problematic footprint from one individual and create a whole new species from it? Yet reporters echo the claim uncritically, relying on Nature to make dependable scientific inferences. No doubt further observations and (hopefully) more prints will cause evolutionists much embarrassment in the future when critics recall the dogmatic statements made this time.

References

[1] Add reference when article is posted.

[2]McNutt, E.J., et al., Footprint evidence of early hominin locomotor diversity at Laetoli, Tanzania. Nature, https://doi.org/10.1038/s41586-021-04187-7, 2021.

[3]Melillo, Stephanie M., Hominin footprints at Laetoli reveal a walk on the wild side. https://www.nature.com/articles/d41586-021-03469-4, 1 December 2021.

[4] Melillo, 2021. emphasis added

[5] Melillo, 2021.

[6] McNutt, et al., 2021.

[7] McNutt, et al., 2021.

[8] Melillo, 2021.

[9] McNutt, et al., 2021.

 [10] Bennett, Matthew, and Sally Christine Reynolds, A new species of early human? Why we should be cautious about new fossil footprint findings, The Conversation, https://theconversation.com/a-new-species-of-early-human-why-we-should-be-cautious-about-new-fossil-footprint-findings-172912, 1 December 2021.

[11] Bennett and Reynolds, 2021.

[12] Marshall, Michael, Fossil footprints hint at mystery hominin with unusual walking style, New Scientist,

https://www.newscientist.com/article/2299611-fossil-footprints-hint-at-mystery-hominin-with-unusual-walking-style/, 1 December 2021.

[13] Olson, Amy, Mysterious footprints in Tanzania made by early humans, not bears, Dartmouth, https://home.dartmouth.edu/news/2021/12/mysterious-footprints-tanzania-made-early-humans-not-bears, 2021.

[14] Olson, 2021.

[15] Choi, Charles Q., Unknown human ancestor may have walked a bit like a bear on its hind legs. Live Science,
https://www.livescience.com/unknown-human-ancestor-footprints-walked-near-lucy, 2021.

[16] Face to Face. Bad Astronomy. http://www.badastronomy.com/bad/misc/hoagland/city.html, 2021.

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Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.