You look familiar...but you seem changed
By Bert Raynes, Jackson Hole, Wyo.
December 24, 2012
A Paul Gauguin painting titled “D’ou Venons Nous / Que Sommes Nous / Ou Allons Nous” is considered a masterpiece. OK, but it puzzles me. For me, this painting doesn’t answer those questions: Where do we come from? What are we? Where are we going?
How could it? Questions like those have been asked for thousands of years. Some people have answers that satisfy them. A lot still look for other answers. They include anthropologists and individuals still searching for themselves.
Anthropologists trace the history of modern humans by following their progress as one of many primates that have appeared in the last 5 million years, looking for that “moment” when bipedal homonids and quadrupedal ones split. Perhaps 4.5 million years ago.
Anthropologists interested in Homo sapiens, us, are fascinated by the challenge of discovering what might be considered truly that moment when it happened — and why or how.
Around 100,000 years ago, the last common ancestor of Neanderthals and of modern humans was Homo heidelbergensis. Homo heidelbergensis is thought to have learned to hunt with stone-tipped spears as long ago as 500,000 years. Early modern humans and Neanderthals each used hafted stone-tipped spears and are know to have coexisted for some thousands of years.
For how many years? When did modern humans become the sole dominant Homo sapiens species? When was that “moment”? What sparked it? Language? Art? Adaptability? Chance?
Can the physical date really be determined? The analytical tests used to date periods hundreds of thousands or millions of years ago produce approximations.
For dates during the period between 12,000 and 52,800 years before present, radiocarbon dating is used; in turn tree rings are used as the basic reference, at least as far back to 12,000 years. (Some investigators have of late felt that the tree rings are not a reliable fundamental reference.)
To the rescue comes the recognition of an ancient lake called Suigetsu on Honshu Island, Japan, that was never covered over by glaciers during the last ice age and so collected seasonal tree leaves from nearby forests for more than 50,000 years.
So each year for 50,000 years two distinct layers of sediment have been deposited: leaf fossil layers and diatom algae fossil layers.
These layers are chemically and visually distinct.
Lake Suigetsu’s sediments form an ideal record of carbon-14 levels because they are undisturbed and are in an oxygen-free environment. (Chemical and Engineering News, October 2012).
Having the lake’s carbon-14 radiocarbon record sampling the atmosphere with more precision should inform on the timing of certain processes in human prehistory.
There seems to be pretty general agreement — in a field in which agreement isn’t simple to achieve — that people who looked like us appeared some 200,000 years ago. Modern Homo sapiens in appearance A question remains of just when behaviorally modern humans evolved.
Good luck with that is my thought. There were Homo sapiens, Homo erectus, Neanderthals, clans or groups all over Africa, Europe, Asia, and the likelihood of a sudden insight or capability (like multiple languages) simultaneously occurring in so many places is ... zilch, is my guess.
Current thinking puts the date that something cataclysmic happened in Europe was about 44,000 years ago. Hunter-gatherers burst upon the scene. Tool making, fire, thin arrowheads, cave painting, all in a rush. Gotta marvel.
Whenever the spark was that made us Homo sapiens occurred, more accurate radiocarbon analytic techniques will help in the search for that date. They’ll also help tell us when things happened in the 50,000 years to today with more accuracy.
Perhaps if Homo sapiens evolves into homo intelligentens some day we will be able to record the period. No sign of it yet.
Field Notes: The weather in Jackson Hole on Sunday, Dec. 16, was a bit tough for bird and man. Wind, snow, poor visibility. Not the greatest day for a bird census. So, the count went ahead anyway.
Preliminary results reflect the difficult conditions. Forty-four species so far reported (Dec. 20) but with more reports to come in to Susan Marsh. Normally close to 60 bird species are recorded at the end-of-the-year census. More later.
Thanks to Susan Marsh, count participants, folks who feed birds, the birds themselves and an anonymous elf at the festive precount breakfast.
Best wishes for the season, the solstice observance and a healthy new year.
© Bert Raynes 2012
Bert Raynes writes weekly on whatever suits his fancy with a dash of news on nature and its many ways.