Behold the Anthropocene: Ecce Homo!
29 Mar, 2015
A Zoologist contemplates the Anthropocene—and an ancient tomb over the ridge visible out his front window
A Cold Day
In a high mountain valley in the eastern Rocky Mountains, 11,700 years ago, a shaman covered the body of a two-year old child with ochre and placed the infant in a secret cave. After praying over the child, she placed over a hundred stone tools representing her peoples’ offerings to the Spirit, and then sealed up the cave lest it be found and the power of the offering lost. Perhaps, she thought, this special child will bring an end to the hard times her people faced.
Later that winter, snow falls in the interior of Greenland bearing a distinctive chemical signature…
The Changes Begin…
The first noticeable changes were the various components of what may be termed “The Great Megafauna Extinction.” Essentially global in nature, this was the extinction or marginalization on a continent-by-continent basis of all large animals throughout the world during the period of 50,000 to 10,000 years before present.
North America loses over 120 species of large animals, including elephants, giant sloths, dire wolves, and several large tiger-sized cats. This is correlated in some form or another, with the arrival or growth of human populations. Farming, world wide, began about 11,000 years before the present, was widespread by 6,000 years before the present, and manmade soils were found worldwide by 500 years ago.
With widespread agriculture occurring by about 8,000 years ago, carbon dioxide started to accumulate in the atmosphere. From a previous low point of about 260 ppm, at the time of the child’s burial, it is now in 2015, about 400 ppm. Comparative evidence indicates that previous seven warm interglacial periods started to stall and reverted to ice ages when the atmospheric carbon dioxide concentrations dropped down to about 240 ppm.
Mankind’s conversion of forest and savannah lands into crop lands had stopped the sequestering of carbon into trees and forests and started the inexorable increase of the atmospheric carbon dioxide level which probably prevented the occurrence of the next glaciation from starting about 8,000 years ago—about 2,000 years before the nascent Egyptian civilization considered building pyramids.
More recent changes continue the trends… The most noticeable result of the arrival of Europeans in the Americas was the death of most of the native population, with an estimated 50,000,000 people being killed by disease and slavery over the next century. Along with this occurred the destruction of both the American and African agricultural systems, as a large portion of the central African cultural base was destroyed by slavery, resulting in the loss of an estimated 125,000,000 acres (50.5 million hectares) of croplands in three continents and the concomitant regrowth of forest, leading again to a drop in the atmospheric carbon dioxide concentration to about 275 ppm, now hypothesized to be a cause of the onset of the “Little Ice Age” in Europe and North America.
Shortly after this, the beginning of Industrialization again reversed the trend and restarted the increase of atmospheric carbon dioxide to what we see today. As this increased through the 19th and 20th centuries, the average global temperature began to rise, first slowly and then more rapidly. Once a critical level was reached, the human population began to increase exponentially, which has led to a positive feedback loop in effects. The last 50 years has seen the melting of the summer Arctic ice cap, progressively warmer winters and summers, the migration of plants and animals poleward and an increase in the growing season. All of these effects can be attributed to growth in human populations. Man’s age has arrived.
As the science of geology developed, it soon became evident that fossils represented three basic types of life correlated with the earth’s age. Eventually, the first fossil assemblages were said to be characteristic of the Paleozoic Era, or the most ancient fossil life. The second fossil groups were said to represent the Mesozoic Era, the “middle life.” This was implicitly a period of transition from the Ancient Life of the Paleozoic to today’s Modern life.
Finally, the last fossil ages were termed the Cenozoic Era, the “modern” life. Derived from the Latin roots for “recent and life” these later geological periods represented the final assemblages of life that took over after the dinosaurs and other Mesozoic life disappeared suddenly. These three primary divisions of the fossil record, these Eras, the Paleozoic, the Mesozoic and the Cenozoic rapidly became well studied, but it took until the latter half of the twentieth century before actual, or absolute, time references for them became necessary and determined.
The End of The Cenozoic Era
All of the geological eras are subdivided into various periods and epochs. If the Paleozoic is considered the first period of fossilized life, and the Mesozoic is the second period, the Cenozoic has been further subdivided into two periods, the Tertiary and the Quaternary, or the third and fourth periods of fossilized life, respectively.
With the advent of precise methodology, there has been an effort to define for every named geological period with an actual physical point where a given boundary of a geological age is defined, visible and able to be sampled. At the present time, the Ice Ages are in the Pleistocene Period, its lower boundary, when all the cold got started, has been determined as 2.58 Million years ago.
A specifically defined and archived ice core take from the Greenland ice cap contains a proxy climate record across the end of the ice ages, the Pleistocene–Holocene boundary. With unprecedented clarity and resolution an array of changes in physical and chemical parameters in cores taken from the Greenland Ice Cap, as well as some freshwater lake bottom sediments and some corresponding cores through marine deep sea sediments show the specific layer, which of course equals a time when the sediments were deposited, when the actual final time, or date for the end of the last ice age, called “The Younger Dryas/Greenland Stadial 1 Cold Phase,” occurs.
This awesome datum shows the specific actual year when the Ice Ages stopped. This is not a abstract time frame, nor an opinion, the datum makes a specific moment after which the ice ages were no more. It was a real year when real people lived.
Published in 2009, this timescale provides an age of 11,700 calendar years before AD 2000 for the base of the Holocene, with a maximum counting error of 99 yr.
Age of Man: The Anthropocene
Within the last several hundred years the impact that our species has had on the planet has become profound. Man has actually become an agent of geological change having an effect on the planet that is every bit as substantial as the more traditional geological factors. For whatever reason it now seems necessary to mark the age of Homo and the real question remaining is how does one do this unambiguously?
One method would be to analyze rocks laid down during mankind’s time on the planet. In the period from 1945 through 1964, several nations participated in atmospheric testing of nuclear weapons. These explosions have left radioactive markers throughout any rocks deposited during that period. This method also is an analogue to the iridium marker for the end of the Mesozoic. The only real problem is that mankind’s manipulative period on the planet significantly predates 1945. So, that date could not, “by definition,” mark the beginning of The Age of Man; it would just be an arbitrary marker. Are there any markers that are more “realistic?” Possibly. Nonetheless, this has led to 1945 as being proposed for the beginning of the Age of Man.
In 1984, I first visited the Palau Archipelago on a diving trip. At that time, that venue as a diving destination was decidedly uncommon. Diving trips had been going there for only a couple of years, and by talking to the guides we estimated that fewer than 1,000 people had been visiting and diving there in the previous several years. Our guides took us to some beautiful, uninhabited, apparently pristine, islands in the outer part of the archipelago. And walking along the beach, what did we find?
We saw what is now found on beaches everywhere, a line of plastic beach trash including plastic hamburger containers from and, as of 2015, fortunately long since phased out of use by, the Golden Arches. It should be pointed out that the nearest large cities likely, at that time to have had a vendor selling Mac Burgers were either Manila, several hundred miles to the west or Honolulu, several thousand miles to the Northeast. Also, ubiquitous were tampon dispensers, pieces of polypropylene rope, and bits and pieces of other debris. About 30 years later, in 2014, a new type of manmade “stone” has been defined: plastiglomerate, the melted-together remains of beach rock, organic debris, and plastic waste found on a beach in the Hawai’ian Islands.
Presumably other versions of this material will be discovered, possibly on other beaches even in boreal or temperate habitats. I am sure anybody would recognize the layer of plastic remains as a marker of mankind found on any beach in the world. The only problems with this being a permanent marker for the age of man is that it has bound to be ephemeral and it is likely to be local in origin. No matter how rugged and resilient plastic seems to be, it is organic and thus subject to eventual bacterial breakdown. Over time it will vanish from the record.
Man At His Best
It has been noted that the arrival of Europeans in the New World was followed over the next century by the demise of most of the Native Americans in both North and South America due to diseases introduced by the Europeans. Recent research has shown that these populations were primarily agricultural and with their deaths, their former crop lands became forested once again resulting in the tremendous growth of forests in the eastern and southern United States as well as throughout Amazonia and the surrounding regions.
Additionally, over the next couple of centuries, the slave trade devastated the Central African agricultural systems and it also resulted in significant destruction of African agriculture and the subsequent regrowth of forests. In turn this unprecedented growth of trees across three continents resulted in the drop in atmospheric carbon dioxide concentrations seen prior to the beginning of the Industrial Revolution. In turn, this low atmospheric carbon dioxide concentration is thought to have resulted in “the Little Ice Age,” which caused a significant drop in the temperature in the northern hemisphere that would only be countered by the increase in temperature seen since the mid-twentieth century due to the burning of fossil fuels and the re-creation of the greenhouse effect that existed in the late Middle Ages. This sequence of events has led to the proposal that the Age of Man should start about 1610.
Man Marks His Territory
Consequently, although there are good proposed defined dates for the Anthropocene, we really don’t have a good, widely accepted geological marker for when it begins, although we do have several markers that unambiguously announce man’s presence. These are refined or manufactured goods that are unlikely to change much even over the tremendous amounts of geological time.
My own suggestions as the ubiquitous markers of man, in shallow marine waters, at least, are things dropped over board from boats. Any diver can verify that most harbors are paved with, at least, a discontinuous layer of beer bottles and aluminum beer cans, both of which will last through the eons of geological time. The silicon dioxide glass and plastic coatings in beer bottles render them functionally impervious to any biological agent.
Eventually, the petrification processes might destroy the bottles’ forms, but the glass will remain essentially forever, albeit if it is ground sufficiently fine, it may be indistinguishable from some types of non-anthropogenic sand. While the aluminum of beer cans is not inert in salt water, it certainly seems that way. It becomes oxidized and then it does not change much over the following human generations. It would be expected to be flattened, so that this particular marker in some future sandstone would be microscopically thin layers of aluminum oxides in marine sediments. Surely this would also be an unmistakable indication that man had been here in ages past.
Finding such remains in the rocks, a classically trained person might say, Ecce Homo, “Behold, Man.” In Latin, this short phrase might reasonably be pronounced as “Eckie Homo” as there are no silent letters in Latin, however, as introduction to humanity in its questionable glory, I think EEKEE! Homo! is really far more appropriate, particularly given the alterations seen in the earth and its environs caused by man.
Since the end of World War Two, changes in the physical and biological environment have occurred at a rate never before seen. We know the three great ages of fossilized life have ended.
The Paleozoic ended in the almost total mass extinction at the end of the Permian period.
The Mesozoic ended in the mass extinction event that occurred during and after the Great Flash – Bang that was the Chicxulub impact.
And, the Cenozoic really ended in the mass extinction event that was the great Megafauanal extinction around the world, starting at the end of the ice ages and signalling the arrival of modern man.
The Ice Ages ended 9,700 ± 99 years BCE. Within the error bars of measurements, at the same time, in what will become in some far future world, a place called Montana, a one-to-two year-old baby boy died and was ritually buried, with an array of fine stone tools. This was not a normal burial. The cost in construction hours of the tools buried with the child was enormous, and the child’s body was covered in ochre, a pigment of ritual powers gathered from specific places of spiritual importance. This burial, in a cave about 600 m from where I am writing this essay, was along what have been found to be migration and trading routes of these Paleolithic hunters. Still in use today, the east-west trading route is Interstate 90, located about 25 miles to the south.
During the construction of an irrigation canal in 1967, the child’s remains and the beautiful tools were exposed and collected. The men who excavated the site as well as the owners of the land eventually recognized the importance of what they had and the remains, the artifacts, and the burial site was all thoroughly studied. Genetic tests showed this child and his people could be considered to be ancestral to almost all Native American tribes.
And then, unlike virtually all other aboriginal burials that have been found in the Americas, the boy’s remains were solemnly and respectfully reburied in 2014 under the protective supervision of the descendants of the shaman and the child’s people. In a real way, here in North America, the end of the Cenozoic Era was marked with the ritual burial of a Homo sapiens sapiens child.
The shaman’s wishes will come true, the awesome cold will finally fade away… But, perhaps, one must be very careful of what one wishes for.
We are now in the fourth great Geological Age of life, one manifested by the effects of humanity on the world. Humans have become a geological force, creating rocks such as plastigomerate out of their own effluvia, as well as altering both the world and the processes governing the physical world. With plastic rocks and crushed beer cans, as well as acidified oceans, and the loss of ice sheets in the high Arctic, we can definitely say, “Ecce Homo, we are in an age of Man.”
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