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The term “Anthropocene” unites the word anthropo, ancient Greek for “humankind”, with the root ‐cene, the standard suffix to denote an epoch in geologic time. Another Greek term of relevance is kairos, which signifies a “moment of transition.” As Moore (2016) remarks, “the Anthropocene concept [is] the most influential concept in environmental studies over the past decade.” But the Anthropocene is more than a concept: it also increasingly constitutes a major influence on the lived experience of Earthlings of all species (Kelly & McDonald 2018), including playing a role in the ending of such experience through species extinction.

While “global‐scale human influence on the environment has been recognized since the 1800s, the term Anthropocene … has only recently [during the 21st century] become widely, but informally, used in the global change research community” (Steffen et al. 2011). It was first introduced by the Nobel Prize‐winning atmospheric chemist Paul Crutzen and the biologist Eugene Stoermer (Crutzen & Stoermer 2000; Crutzen 2002). A primary driver of its acceptance as a meaningful and needed concept is the multiple Earth‐changing effects of climate change. But “climate change is only the tip of the iceberg” (Steffen et al. 2011). Human actions have also changed the life‐sustaining cycles of key elements such as nitrogen, phosphorus, and sulfur. The nitrogen cycle has been altered through the production and use of fertilizer, deforestation, and the burning of fossil fuels. The massive amounts of nitrogen that humans produce—they at their highest level today for 2.5 billion years—are reshaping the world’s ecosystems (Lewis & Maslin 2015). The phosphorous cycle has been changed by fertilizer use and the rearing of livestock (especially hogs), as well as by the use of detergents containing sodium tripolyphoshate. The sulfur cycle has been changed by the burning of fossil fuels, which increases the amount of sulfur in both the atmosphere and the oceans. Moreover, human activities have altered the terrestrial water cycle via dam building, river course modification, and the elimination of riverside wetlands, as well as through changes in land cover that modify the flow of water vapor from the land to the atmosphere. Another human impact is an acceleration of species extinctions to such a degree that it has raised questions about whether we are on the threshold of a mass extermination on par with the one that nearly eliminated the dinosaurs (nearly, and not totally, because the dinosaur ancestors of modern birds survived). In short, human activities are so widespread and so profound in the ways they are changing Earth that they have begun to threaten the very life‐support systems upon which we and all other species depend (Steffen et al. 2005; Waters et al. 2016). The concept of the Anthropocene was developed to call attention to this human‐driven quantitative shift in the geochronology of the planet. As Meyer (2018) comments, “[i]t is a stirring idea: that humans are not a momentary blip in the long procession of Earth’s history, but a new and fundamental driver of planetary change, equal in stature to volcanoes and tectonic plates.” In terms of the actual effects we are having on the planet, it also is a disturbing one.

How do earth scientists determine geochronology? The process involves ongoing data collection, international expert discussion, and committee consensus. Critical components occur within the International Union of Geological Sciences (IUGS), an international nongovernmental organization concerned with promoting international cooperation in the scientific field of geology. The Union manages six international commissions, including the International Commission on Stratigraphy (ICS), which is responsible for setting the stages and boundary markers of the geochronology of Earth history and for naming geological eras. In the language of the ICS, a historical epoch is defined as a subdivision of the geologic timescale that is longer than an age but shorter than a period. By way of analogy, in measuring the dimension of length, a foot is longer than an inch but shorter than a yard.

The establishment of an epochal change the geologic timescale generally is based on the identification of significant changes in the rock layers of Earth’s stratigraphy. The conceptualization of the Anthropocene hinges on the idea that the geological epoch known as the Holocene (Greek for “entirely recent”), which began approximately 11 650 calendar years before the present, has ended, because “humankind has become a global geological force in its own right” (Steffen et al. 2005). The ICS has not as yet accepted the Anthropocene as a formally defined geological unit within the Geological Time Scale, though its Anthropocene working group has concluded that it is a plausible new layer in Earth geochronology. Establishing the Anthropocene as an accepted geologic unit of time requires that the ICS either: 1) identify a specific location in rock, sediment, or glacier ice that marks the transition to a new epoch (e.g., the Precambrian–Cambrian boundary marker has been placed at Fortune Head, Newfoundland, where there is clear fossil evidence of a lifeform transition); or 2) agree on a date for this transition, based on a survey of the available stratigraphic evidence. Various dates, such as the beginning of the Industrial Revolution, with its ever‐accelerating level of fossil fuel use and abundant greenhouse gas emissions (Crutzen 2002), or the period between 1945 and 1988, when nuclear weapons were tested with such frequency that their worldwide fallout left an identifiable mark in the chemostratigraphic record (Zalasiewicz et al. 2015), have been proposed.

One of the most curious features in the evidence for the Anthropocene involves the common domestic broiler chicken, the source of everything from buffalo wings to pre‐sliced deli meat chicken sandwiches. While thus far no individual taxa have been suggested as the distinct marker of the Anthropocene, Bennett et al. (2018) propose Gallus gallus domesticus as the best choice. Driving the rise and global spread of this heavily engineered bird are human population growth, commercially impacted human consumption trends, and drops in the populations of wild animals. It is now by far the most numerous bird species around, with an estimated population of almost 23 billion individuals. This is an order of magnitude larger than stocks of the most abundant existing wild bird species, such as house sparrows, common pigeons, and red‐billed quelea, as well as the extinct passenger pigeon, and is likely the largest population size ever achieved by a single species in the 160 million‐year history of birds. Because of selective industrial breeding, the broiler chicken is distinctive in overall size, weight, bone size, genetic make‐up, and appearance from its wild progenitor, the red jungle fowl. In 2016, over 65 billion broilers were consumed globally. Production and consumption data mean “that the potential rate of carcass accumulation of chickens is unprecedented in the natural world” (Bennett et al. 2018). Much of this global accumulation finds its way into landfill sites by way of domestic garbage removal systems. Organic materials like chicken bones are often well preserved in landfills because their anaerobic conditions tend to mummify organic deposits (Rathje & Murphy 2001). Consequently, the broiler chicken produces a particularly widely distributed and distinctive biostratigraphic signal in the sedimentary record, allowing it to serve as a key fossil index taxon of the Anthropocene.

While the ICS has not recognized the Anthropocene (Finney & Edwards 2016; Gibbard 2018), many scientists have. The concept has gained de facto authority even if it is not officially sanctioned, as reflected in the launching of multiple new academic journals, such as The Anthropocene, The Anthropocene Review, Elementa: Science of the Anthropocene, and Anthropocene Coasts, the organization of professional conferences sponsored by universities and scholarly groups, and the publication of an ever‐growing international and multidisciplinary scientific literature on the topic (e.g., Zalasiewicz et al. 2017; Hughes et al. 2018; Steffen et al. 2018; Tucker et al. 2018).

Ultimately, whether or not the ICS decides that the Anthropocene meets the criteria for the establishment of an epoch in Earth history, it does not change the reality of the “perfect storm” of interacting human impacts on the planet, its global processes and ecosystems, and its lifeforms. For those at gravest risk from ecocrises interaction, whether their loss of access to adequate food, breathable air, survivable temperatures, or dry land occurs during a particular scientifically defined segment of geological time on ICS’ International Chronostratigraphic Chart is of negligible importance. What does matter is the utility of Anthropocene recognition in spurring useful new research and practical political and social action to avert a slide into hothouse Earth conditions.