I know that much has been written on this elsewhere over the last few days, but this blog is about the stories that sand can tell us - how could I possibly omit this one? The image above is indistinguishable from what we would see if we looked over our shoulder as we were enjoying the sensation of sand between our toes on the beach. But this footprint is 1.5 million years old.
In the latest issue of Science, an again satisfyingly international group of researchers (from the UK, the US, South Africa, and Kenya) report on the discovery at Ileret, in Northern Kenya, of extraordinary sets of footprints of our ancestors, in this case Homo ergaster, an earlier, larger version of the widespread Homo erectus. Analysis of the tracks shows that, in terms of their gait and posture, these people (and I see no reason not to use that word) walked through the sand in exactly the way we do. Their journey took them across ancient river beds along the edge of Lake Turkana, through a landscape that would have differed little from today's, periodic flash floods sweeping down the valleys, showers of ash falling from erupting volcanoes. Lake Turkana is the northernmost of the great lakes of the East African Rift Valleys, the fault-bounded scars of long-lived crustal extension, and geologically active landscapes. It would seem quite likely that this group of our ancient relatives were hastening to avoid a flooding river - it was the sand carried by that shifting river that filled in their footprints and preserved them for us to wonder at. It's easy to forget how literally fragmented is the record of our ancestors, broken and dispersed by active geology, and, while preserved footprints are even more rare than bone fragments, they nevertheless have an emotional immediacy. We look at the photo above and know the sensation of the person as they made it, we can identify with them.
The science is fascinating, and sources are listed below, but for me, and probably for most of us, it's that emotional identification, the resonance that is so compelling. In the words of Henry Wadsworth Longfellow (modified slightly to recognize the greatness of both genders):
Lives of great men and women all remind us
We can make our lives sublime,
And departing, leave behind us
Footprints on the sands of time.
[https://www.sciencemag.org/cgi/content/abstract/323/5918/1197; https://archaeology.about.com/b/2009/02/26/ancient-human-footprint-discovery-in-kenya.htm; https://www.sciam.com/article.cfm?id=15-million-footprints-uncover. Footprint photo Professor Matthew Bennett, Bournemouth University; Rift Valleys map, USGS]