The bony armour of the glyptodon tail felt lighter than I thought it would. This ice age mammal could stretch out to nearly 3.5 metres and weigh in at two tonnes. This relative of the armadillo had a massive protective shell made up of hundreds of 2.5-cm-thick bone platelets. An adult’s shell easily measuring a metre and a half high could have been used, some paleontologists believe, as an emergency shelter by early hunters.
Andres Rindernecht, director of paleontology at Uruguay’s National Museum of Natural History, placed the glyptodon fossil back in its box as he continued to show my wife Eva and me through the dusty warren of shelves packed with thousands of sample cases and boxes earlier this month. The museum has been closed for some years to the public because of a lack of funding, space and staff to properly exhibit its collections.
Senor Rindernecht noted that evidence had not been found of human hunters butchering a glyptodon. Ancient kill sites such as Tibilo on the Sabana de Bogota in the northwest corner of the South American continent in Colombia, though, show first peoples hunting megafauna there, like mastodon, some 12,000 years ago. Stone tools found in the same strata of an Uruguayan dig as glyptodon bones certainly prove a human presence around the time these big creatures went extinct some 10,000 years ago.
What role did human predation play in the extinction of the megafauna of the Americas like the glyptodon and mammoth? Did our ancestors know what impact they were having on their environment? Did the pressure just to survive outweigh any other thought?
A new study, “Reconciling migration models to the Americas with the variation of North American native mitogenomes,” by Alessandro Achilli et al. in the Proceedings of the National Academy of Sciences August 12th Early Edition highlights the complexity of the peopling of the Americas. Three different source populations for Native Americans have been identified in a recent genome-wide scan of Native American and Siberian groups.
However the theory which suggested that the “Americas were settled through three separate population movements whose identity was expressed in linguistic terms as Amerinds, Na-Dene, and Eskimo-Aleut speakers” appears “far too simplistic.” These researchers suggest that “analyses of these two latter haplogroups have led to the conclusion that they might have been carried to North America by Beringian populations. These arrived through the ice-free corridor between the Laurentide and Cordilleran ice sheets, either concomitantly or some time after the southward spread of the Beringian groups who were instead following the Pacific coastal route.”
When and by which ever route they came, they all shared a set of behaviours that by about 100,000 years ago had dramatically set our species apart from all other creatures on the planet, according to biologists Ajit Varki and Danny Brower in their new book Denial: Self-Deception, False Beliefs, and the Origins of the Human Mind. Symbolic art, grave and personal adornments demonstrated a breakthrough interest in humans perception of others they argued. This awareness led our ancient ancestors to the disturbing awareness of their own mortality. To calm this fear our species, they argue, developed the unique ability to deny reality, giving rise, among other things, eventually to religion and philosophy.
As Daisy Yuhas, reviewing their book in the September-October issue of Scientific American Mind, reflects the “gift for self-deception may have saved our ancestors from despair.” However this abilityto
blithely ignore reality can lead us to the precipice as well. Yuhas goes on optimistically to suggest that “recognizing this tendency in ourselves may push us to stop ignoring unpleasant truths, such as global warming and poverty, and start addressing them.”
However we got here, we should try to know where we are going. If we learn to face the facts of our current situation truthfully we may just avoid going the way of the glyptodon ourselves.
Michael Dougherty is co-chair of the social justice committee of Sacred Heart Cathedral of Whitehorse.