A brief moment in the magnificent history of mankind

By PZ Myers

Blogging on Peer-Reviewed Research

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Isn't that beautiful? It's an ancient footprint in some lumpy rocks in Kenya…but it is 1½ million years old. It comes from the Koobi Fora formation, familiar to anyone who follows human evolution, and is probably from _Homo ergaster_. There aren't a lot of them; one series of three hominin trails containing 2-7 prints, and a stratigraphically separate section with one trail of 2 prints and an isolated single print. But there they are, a preserved record of a trivial event — a few of our remote relatives taking a walk across a mudflat by a river — rendered awesome by their rarity and the magnitude of the time separating us.

Here's one of the trails:

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(Click for larger image)Tessellated swath of optical laser scans of the main footprint trail on the upper footprint surface at FwJj14E. Color is rendered with 5-mm isopleths.

It's an interesting bridge across time. There they were, a couple of pre-humans out for a stroll, perhaps on their way to find something for lunch, or strolling off to urinate, probably nothing dramatic, and these few footprints were left in drying mud to be found over a million years later, when they would be scanned with a laser, digitized, and analyzed with sophisticated software, and then uploaded to a digital network where everyone in the world can take a look at them. Something so ephemeral can be translated across incomprehensible ages…I don't know about you, but I'm wondering about the possible future fate of the debris of my life that has ended up in landfills, or the other small smudges across the landscape that I've left behind me.

And what have we learned? The analysis has looked at the shape of the foot, the angle of the big toe, the distribution of weight as the hominins walked across the substrate, all the anatomical and physiological details that can be possibly extracted from a few footprints.

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(Click for larger image) Optical laser scan images color-rendered with 5-mm isopleths for footprints at both FwJj14E and GaJi10. (A) Isolated left foot (FUI1) on the upper footprint surface at FwJj14E. (B) Photograph of FUI8 on the upper footprint surface at FwJj14E, showing good definition of the toe pads; the second toe is partially obscured by the third toe. (C) Second trail on the upper footprint surface at FwJj14E, showing two left feet. (D) Third trail on the upper footprint surface at FwJj14E, showing a right and a left foot. (E) Print R3 from GaJi10 (22), re-excavated and scanned as part of this investigation. (F) Partial print (FUT1-2) on the upper footprint surface at FwJj14E; the heel area has been removed by a later bovid print. (G) Print FLI1 on the lower footprint surface at FwJj14E, rendered with 5-mm alternating black and white isopleths. (H) Inverted image of the toe area of print FUT1-1 with alternating 5-mm black and white isopleths. Note the locations of the pads of the small toes and the presence of a well-defined ball beneath the hallucial metatarsophalangeal joint. The first, third, and fifth toes are marked D1, D3, and D5, respectively.

The answer is that these beings walked just like us. The tracks are noticeably different from the even older footprints of australopithecines found at Laetoli, from 3.5 million years ago. The foot shape and the stride of _Homo ergaster_ was statistically indistinguishable from those of modern humans, even though we know from the bones associated with these species that they were cranially distinct from us. This is not a surprise; it's been known for a long time that we evolved these bipedal forms long ago, and that the cerebral innovations we regard as so characteristic of humanity are a relative late-comer in our history.

Remember, though, these are _1½ million years old_, 250 times older than the age of the earth, according to creationists. That's a lot of wonder and history and evidence to throw away, but they do it anyway.

Bennet MR, Harris JWK, Richmond BG, Braun DR, Mbua E, Kiura P, Olago D, Kibunjia M, Omuombo C, Behrensmeyer AK, Huddart D, Gonzalez S (2009) Early Hominin Foot Morphology Based on 1.5-Million-Year-Old Footprints from Ileret, Kenya. Science 323(5918):1197-1201.