differing in structure and filling the same place in nature, I must suspect they are only varieties. The only fact of a similar kind of which I am aware, is the constant asserted difference between the wolf-like fox of East and West Falkland Islands. If there is the slightest foundation for these remarks, the zoology of archipelagoes will be well worth examining; for such facts would undermine the stability of species.6
The phrase “such facts would undermine the stability of species,” written down for the first time in his notebooks documenting the five-year voyage of the HMS Beagle, point toward a theory that only emerged in print two decades later. Immediately recognized by the other revolutionary giant of the nineteenth century, Karl Marx, the importance of Darwin’s On the Origin of Species by Means of Natural Selection, or, the Preservation of Favoured Races in the Struggle for Life, could not be overestimated. According to Marx, Darwin’s book, published in 1859, was an “epoch-making work” that formed “the basis in natural history for our view,” because it undermined the God-centered view of creation and gave life science a firm theoretical footing on solid materialist ground.7
Giant tortoises have existed on Earth for ten million years. In contrast, Homo sapiens have walked the Earth for approximately 200,000 years, a mere 2 percent of that time.* Yet in less than the life span of one individual giant tortoise, the subspecies has gone from numerous enough to fill the holds of ships to the extermination of all of C. nigra abingdonii by humans. In the world as it currently exists, the extinction of this giant tortoise leaves us not with the question “will we learn?” but with “which species will be threatened next?”
Perhaps it will be the leatherback turtle. The International Union for the Conservation of Nature (IUCN), the world’s oldest and largest nature conservation organization, which compiles the Red List of Threatened Species, has placed this primordial leviathan on the “critically endangered” list—one category away from “extinct in the wild.”
Relics of a distant past, leatherbacks have existed on Earth practically unchanged for 100 million years—ten times longer than the Galápagos tortoises. Next to the leatherback, Homo sapiens pales into temporal insignificance. Mature leatherbacks can be over six feet long, four feet wide, and weigh up to a ton. Able to swim to depths of 3,600 feet—over three times deeper than a nuclear submarine—leatherbacks change their body temperature to cope with the cold, their pliant shells allowing them to survive the immense pressure of the ocean depths.
To sit on a tropical beach in the middle of the night, close to an egg-laying mother, listening to the heaving power of her gargantuan lungs, gazing at a creature of such evolutionary perfection, is a deeply affecting moment. How much will humanity lose if these creatures are lost forever?
We don’t know exactly what the average leatherback life span is, but we do know that species placed on the critically endangered list are likely to be extinct within ten years. Leatherbacks have experienced a population decline of more than 90 percent since 1980.
The turtles are threatened by the full gamut of economic activities dictated by the profit motive. Industrialized fishing methods, such as gillnet, trawl, and long-line fishing, trap the turtles as unwanted “bycatch.” One study of Pacific Ocean turtles estimates that more than 200,000 loggerheads and 50,000 leatherbacks are killed each year solely through inadvertent entanglement in long-line fishing.8
Just as turtles have become rare, the system responds and sets in motion further declines. Local consumption of turtles and their eggs was once a sustainable practice, but with the growth in world trade, a highly profitable multinational black market in turtle eggs has developed. While a turtle egg might sell for $1 in Costa Rica (a not insignificant sum considering a single nest can hold more than fifty of the perfectly round, pearl-white eggs), international consumption and smuggling associated with the drug trade means the price can reach as high as $100 to $300 per egg in international markets.9
As turtles return to the same beach that they were born on, largely unchecked coastal economic growth for tourism or real estate development is a further threat. Electric lighting on previously dark beaches confuses the turtles’ navigation, resulting in fewer females making it onto land to lay their eggs.
Along with thousands of other species, leatherbacks are threatened with extinction by an economic and social system that is based on relentless, profit-driven expansion that promotes industrial fishing methods, chemical pollution, and egg harvesting for the black market. Which begs the question: How can we save these magnificent wild animals and, by extension, humans?
The current biodiversity crisis, whereby species are being driven to extinction at rates up to a thousand times greater than the geological statistical norm, is simply one aspect of a global ecological crisis. Whereas in the past such crises were local or regional, humans are now changing the whole biosphere in a multiplicity of ways: our actions are changing the chemical composition of the atmosphere; acidifying the oceans; contaminating the soil, the water, the air, and organisms worldwide with toxic chemicals; altering the land through deforestation of vast areas of tropical and boreal forests; and warming the entire planet. Whereas once we wiped out individual species, now we threaten whole biota.
THE AGE OF HUMAN-INDUCED GLOBAL CHANGES
The decline of sea turtle populations is but one example of the changes to global ecosystems that have been caused by human activity. Since the end of the last ice age about 12,000 years ago, humans have lived in the geological epoch called the Holocene. But according to the 2016 panel of geologists convened to examine the issue, in their report to the Geological Congress, we have now entered a new geological epoch: the Anthropocene, which is dominated by the activities of a single species. Scientists have drawn this conclusion from an analysis of the long-term impacts of human activities on the biosphere: climate change from fossil fuel combustion that increases carbon dioxide concentrations in the atmosphere and causes ocean acidification, plastic pollution, the disruption of the natural cycles of nitrogen and phosphorus by modern methods of agriculture, the widespread introduction of toxins into the environment, and the irradiation of the atmosphere from nuclear weapons testing.
One way of viewing these huge changes has been put forward by an international group of scientists who proposed nine planetary boundaries “within which humanity can continue to develop and thrive for generations to come.”10 We have already crossed or are close to crossing four of these nine boundaries—climate change, biosphere integrity, land-system change, and the nitrogen and phosphorus cycles. As lead researcher Will Steffen notes, “Transgressing a boundary increases the risk that human activities could inadvertently drive the Earth System into a much less hospitable state, damaging efforts to reduce poverty and leading to a deterioration of human well-being in many parts of the world, including wealthy countries.”11 One of the proposed boundaries is biodiversity, or “biosphere integrity.” As Colin Waters and his colleagues note in Science magazine:
Although Earth still retains most of the species that were present at the start of the Holocene, even conservative estimates of extinction rates since 1500 CE are far above mean per-million-year background rates, with a notable increase from the 19th century onward. Current trends of habitat loss and overexploitation, if maintained, would push Earth into the sixth mass extinction event (with ~75 percent of species extinct) in the next few centuries, a process that is probably already underway.12
The article goes on to note that the most significant reason for mass extinction is due to land-use changes and the restriction of “wild” nature to smaller and smaller areas. “The terrestrial biosphere has undergone a dramatic modification from 1700 CE, when almost 50% of the global ice-free land area was wild and only ~5% was intensively used by humans, to 2000 CE, when the respective percentages were 25% and 55%.”13
Species evolve in interaction with one another and depend on the presence of others. Thus, when one species becomes extinct or shifts its range, detrimental effects may occur to the stability and survival prospects of other species and the healthy functioning of the ecosystem as a whole.
The Warming Planet