In the story of Robinson Crusoe, a man finds himself shipwrecked on an uninhabited tropical island. Unlike Tom Hank’s character in Castaway, though, Crusoe learns to live quite comfortably and carefree for 28 years despite the desolate isolation.
Until the day he finds a human footprint on the beach.
This encounter, one of the most famous episodes in English literature, evokes all kinds of emotions from Crusoe, all centered on one fact: someone else has been here!
That account is fictional, but a real-life version of it played out again today in the world of paleontology. Today, scientists announced finding a set of fossilized hominid footprints in Tanzania. You can read the original paper here, or more user-friendly versions from BBC or The Guardian if you prefer. Just like a freshly poured sidewalk in the inner core of any major 21st century city which permanently features heel prints, a bike tire tread and/or some message scrawled by fingertip, this sun-baked surface hardened by time and weather … and dated to almost 3.7 million years ago … forever captures the casual walk-around-the-block of some Paleolithic couple, along with the tracks of other mammals, birds, and insects. You can even see raindrop impressions in it!
This isn’t the first time that the ancient Tanzanian pavement told us “someone’s been here before.” Another set of tracks were found in 1978 about 150 meters away from the ones described today, and made world headlines at that time as the earliest evidence that our ancestors walked upright.
“So what’s the big deal about finding some old footprints?” you might ask.
Let me tell you.
They help paint the picture of a typical day-in-the-life of ancient hominids that you just can’t get from looking at their dry dusty bones.
Judging from the lengths of their strides and the depth of the impressions they made in the ancient mud, the tracks found 40 years ago show one small hominid walking to the left of a much larger individual, while an intermediate-sized individual is carefully stepping into the holes made by the largest one: it’s hard not to picture a father and child walking side-by-side while mama follows dutifully behind.
Today’s announcement describes 14 other sets of tracks from two individuals walking in the same direction as the previous three, and seemingly just a stone-throw away. Judging from the size of their steps, one of them was relatively speaking a giant … far taller than the average for the hominid species which today’s experts think walked those trails at that particular time (Australopithecus afarensis, if you must ask). And again, their tracks mingled with those of ancient versions of giraffes, horses, rhinos, and birds. Can’t you picture them, cautiously crossing an open savanna, scanning around nervously for predators, a rainbow off in the distance as the storm clouds angrily retreat to the horizon?
These collections of tracks tell us certain things that are plainly obvious and mundane: that ancient hominids walked upright as far back as 3 or 4 million years ago, were quite social (preferring not to walk alone), and that even the adults came in different sizes.
But from all that we may also be able to infer something about their sex life!? The differences in their heights suggest the family units might be more like that of gorillas than of chimpanzees. Gorillas tend to have one large male and several smaller females producing the next generation. Adult male and female chimps, on the other hand, don’t show nearly as much size differences and have no unspoken or strictly enforced rules about who gets to mate with whom. What a tale those trails can tell.
I’ve often referred to the collections of ancient hominid bones as being like our family photo album, with snapshots of various awkward uncles, aunts and cousins being added as the years go by: beginning with Neanderthals and Homo erectus in the 1800s, and then Aunt “Lucy” (Australopithecus) in the early 1900s, we add Uncle “Ardi” (Ardipithecus) in 1994, “the hobbit” (Homo floresiensis) in 2004, Denisovans in 2008, and Homo naledi in 2015.
But these footprints are the paleontological equivalent of the video many parents now make of their baby’s first steps!
Picturing that couple stepping cautiously toward the distant horizon of their open savanna, an ancient version of Abram and Sara trekking to a new and promised land, I can’t help wondering about whether they were also beginning to develop some kind of sense of a “Great Being.” We know that humans began building grandiose temples of various kinds all around the world ten thousand years ago (Stonehenge; Mayan and Aztec temples; Egyptian pyramids; Babylonian temples). And that we (and Neanderthals) were carefully burying our dead together with tools, weapons, food and jewelry hundreds of thousand years before that. But what kind of concept of the afterlife did we have millennia before that when we first started scratching images on cave walls? And were the cognitive seeds of that preoccupation with the supernatural also present in these very earliest of hominids, who were part of our evolutionary journey?
Lots of food for thought for those of us trying to fit together scientific findings like these with the belief system we grew up with, portraying a primal couple six thousand years ago.
One final thought before closing this blog post on the subject of fossilized hominid footprints: it’s worth pointing out what was not found in either of the ancient Tanzanian trails described above, since I’m sure this point will come up often in the dialogues and comments that follow today’s announcement. What they didn’t find was footprints of humans and dinosaurs together. There are still some who continue to believe that humans walked with the dinosaurs because they’ve heard about fossilized footprints in the limestone beds of the Paluxy River, near Glen Rose, Texas. However, careful examination of those tracks by expert paleontologists have shown the “human” tracks were in fact been made by another species of dinosaur.
Nonetheless, some stand firm in their belief to the contrary, based on second- or third-hand information from non-experts and a deception perpetuated by exhibits such as those found at the Creation Museum in Petersburg, Kentucky: in portraying humans and dinosaurs co-existing, the latter continue to put an image in people’s minds which then becomes truth to them. The fact is, no expert paleontologist—someone who has spent decades studying things like this in great detail and who understand the mechanisms—will agree that we have evidence of any kind for humans and dinosaurs co-existing, and mountains of evidence refuting the idea. No one can produce fossilized remains of humans intermixed with those of T. rex or any other of his cousins.
Perhaps someone should tell Fred Flintstone.
Let me know what you think of today’s announcement…