Welcome to the Anthropocene
World War You Too?
by Guest Blogger,
Tyler Kokjohn, Ph.D.
A group of experts believes Earth entered a new geologic epoch, the Anthropocene, around 1950 (1, 2). The hallmarks of this new age are radioactive fallout and other traces of human activities distributed across the entire world. Although the human influences on planet Earth have been profound, assigning a precise start date to an epoch is challenging, controversial and almost unprecedented.
Planet Earth and the life aboard her endured radical environmental changes before humans appeared. Some were so cataclysmic they left unmistakable fossil records of correlated mass extinction events. The full ramifications of the changes being unleased in the Anthropocene are uncertain. However, accumulating evidence suggests a sixth planetary mass extinction event, promoted by multiple factors including habitat destruction, careless releases of toxic contaminants and the predatory activities of humans, is well underway (3, 4).
In some instances the links between human activities and species loss are clear; claiming grasslands for agriculture combined with other factors including improperly managed hunting extirpated vast prairie tracts and enormous herds of the American Bison. However, identifying the key culprits leading to recently noted declines in honeybee and other pollinator insect populations has been a challenge. The case of honeybees is troubling because we shelter and care for them. If human activities have pushed many of our planetary co-inhabitants to extinction and we are seeing honeybees, migratory Monarch butterflies and a host of other cherished creatures vanishing, could we be harming ourselves as well?
What does an extinction in progress look like? California has been overwhelmed by terrible wildfires recently. A long drought has been blamed for the mass tree deaths that converted forests into tinderboxes. The drought is a critical factor, but the wide scale catastrophe unfolding in the forests is due to a combination of factors including weather conditions that favor bark beetles and opportunistic microbial pathogens (5). Separate elements working in concert weakened, damaged and finally killed the vast expanses of trees now just waiting to burn. Perhaps some extinctions are the culmination of multiple factors and we are witnessing domestic honeybees being pushed into oblivion by a combination of situations like pesticide exposures and the management methods used by their human overseers.
By numeric measures such as life expectancy and population levels, it is clear science and technology have served humanity well. We can produce more food faster and cheaper than ever, so it would seem the biotech revolution is living up to its promise. But could some positive results be deceiving us? Genetically modified (GM) crops compose a significant portion of food production. Foods containing GM ingredients have been tested and deemed safe for human and animal consumption by regulatory agencies although these conclusions have been controversial. However, the full ecological implications of some GM crop production methods are unknown. Genetically engineered herbicide-resistant crops are treated with glyphosate, one of the most widely used weed control agents in agriculture (6). Judged by crop yields and profits, this GM crop/glyphosate combination has been a huge success economically. Glyphosate has several advantages, but some studies and observations suggest its use changes the species composition of microbial communities and impairs activities essential to maintain soil health and function (6, 7).
Concerns over the long term consequences of glyphosate use seem similar to the multiple chronic disease issues such as obesity, diabetes and allergies now being linked with antibiotic use (8). Perhaps the lesson for us is that artificially destabilizing complex microbial ecosystems with antibiotics or chemical agents leads to undesirable outcomes.
Some scientists have hypothesized rising obesity rates could reverse the long-standing positive trend of increasing average life expectancy (9). Public health authorities are attempting to counter an emerging obesity epidemic with education programs that encourage better eating habits and physical activity. In the future physicians will devise more ways to reconstitute essential microbes eliminated after antibiotic treatments and perhaps agricultural scientists will amend damaged soils to keep them productive after heavy herbicide use if and when such actions become necessary. Maybe technological fixes will keep pace with developing issues.
What happens if the combined effects of our actions – antibiotic use, diets, food production methods – quietly drive to extinction the microbes essential to human health or ecosystem function? Evidence suggests that colon cancer development risk is influenced by gut microbes (10) and the success or failure of some anti-cancer treatments hinges on the gut microbial flora as well (11). Could we realize our technologies and lifestyles unwittingly eliminated the microbes needed to develop properly functioning immune systems, prevent or treat certain deadly cancers and maintain life-sustaining ecosystems? Maybe our path to extinction will involve self-inflicted obesity, pandemics of untreatable diseases and crop failures.
Do the trees and honeybees offer any lessons for us? Maybe they are saying something about our future;
Welcome to the Anthropocene, when humans took control of our home planet. No one gets out of here alive.
(1) P. Voosen. 2016. Atomic Bombs and Oil Addiction Herald Earth’s New Epoch: The Anthropocene. Science, 24 August 2016. http://www.sciencemag.org/news/2016/08/atomic-bombs-and-oil-addiction-herald-earth-s-new-epoch-anthropocene
(2) D. Carrington. 2016. The Anthropocene Epoch: Scientists Declare Dawn of Human-Influenced Age. The Guardian, 29 August 2016. https://www.theguardian.com/environment/2016/aug/29/declare-anthropocene-epoch-experts-urge-geological-congress-human-impact-earth
(3) J. Dyke. 2015. Earth’s Sixth Mass Extinction Has Begun, A New Study Confirms. The Conversation, 19 June 2015. http://theconversation.com/earths-sixth-mass-extinction-has-begun-new-study-confirms-43432
(4) S. Kaplan. 2015. The Washington Post, 22 June 2015. https://www.washingtonpost.com/news/morning-mix/wp/2015/06/22/the-earth-is-on-the-brink-of-a-sixth-mass-extinction-scientists-say-and-its-humans-fault/
(5) C. H. Craft. 2016. Like Tens of Millions of Matchsticks, California’s Dead Trees Stand Ready to Burn. The New York Times, 29 August 2016. http://www.nytimes.com/2016/08/30/science/california-dead-trees-forest-fires.html
(6) M. M. Newman et al. 2016. Glyphosphate Effects on Soil Rhizosphere-Associated Bacterial Communities. Science of the Total Environment 543:155-160. http://www.sciencedirect.com/science/article/pii/S004896971530989X
(7) S. Strom. 2013. Misgivings About How a Weed Killer Affects the Soil. The New York Times, 19 September 2013. http://www.nytimes.com/2013/09/20/business/misgivings-about-how-a-weed-killer-affects-the-soil.html
(8) M. J. Blaser. 2016. Antibiotic Use and its Consequences for the Normal Microbiome. Science, 352: 544-545. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939477/
(9) S. J. Olshansky et al. 2005. A Potential Decline in Life Expectancy in the United States in the 21st Century. The New England Journal of Medicine 352:1138-1145. http://www.nejm.org/doi/full/10.1056/NEJMsr043743
(10) I. Sobhani et al. Microbial Dysbiosis and Colon Carcinogenesis: Could Colon Cancer Considered a Bacteria-Related Disease? Therapeutic Advances in Gastroenterology 6(3):215-229. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3625019/
(11) M. Leslie. 2015. Gut Microbes Give Anticancer Treatments a Boost. Science, 5 November 2015. http://www.sciencemag.org/news/2015/11/gut-microbes-give-anticancer-treatments-boost
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