by Elizabeth Kolbert 2014
Book Review by Ray Herrmann
The notion of "extinction" was unheard of until it was proposed by Naturalist Jean Cuvier in 1796 to explain some sudden disappearances of fossils in newer eras. Initially his theory was rejected, but as evidence of many more extinctions mounted (Mammoths, Mastodons giant Sloth's …), it became accepted. Extinction was further made obvious by the finding of many dinosaur fossils.
The author examines many cases of species die-backs or extinctions, including the Panamanian Golden Frog, Great Auks, Bats and Corals. Frogs and Bats are still succumbing to fungi that were probably unwittingly spread by Man's activities.
The Great Auk was an unassuming, slow, large flightless bird (like large penguins) that nested on an island near Norway. They were so easy to catch that people scooped them up by the hundreds; ate some, burned others as fuel to cook Auks, and harvested their feathers while letting their naked bodies free to freeze to death. This story reminded me of how we treated the Dodo Birds or the Buffalo in the West in the 1800's.
It has been estimated that one-third of all reef-building corals, a third of all fresh water mollusks, sharks and rays, a quarter of all mammals, a fifth of all reptiles and a sixth of all birds are headed for extinction! Coral reefs are being driven to extinction by three things: Water Turbidity resulting from increased pollution, the rise in Temperature and the Acidification caused by absorbing CO2 (forming Carbonic Acid); these last two being due to Global Warming. In 2014, oceans absorbed 2 1/2 billion tons of CO2, forming Carbonic Acid. And that rate increases most every year. Since about 1800, the PH of the oceans has dropped from 8.2 to 8.1 (lower = more acidic. A decline of 0.1 means that oceans are 30% more acidic than they were before). Ocean PH is expected to drop to 8.0 by mid-century. Near 7.8 most marine life dies.
What drives Extinctions? Extinction is when a species birth rate falls below its death rate. It seems to be driven by changes that affect the environment in which a species has evolved to live (climate, food, water, predators or disease). If these changes come slowly (over hundreds of generations) a species might be able to evolve enough to survive.
In eastern Peru, stating in 2003, tests were conducted up a mountainside on 17 environments at different elevations ranging to over 11,000 feet. These were marked off into 2 1/2 acre plots. The diversity of species was seen to drop as the elevation rose and the average temperature dropped (usually ~ 50ºF but dropping 2ºF with only ~800 ft elevation). Yet this small change was enough to drastically change the mix of species. Conclusion: Species are very sensitive to local conditions.
Studies on islands found that the number of species declined as the available area decreased. This follows a general formula where (number of species "S") S = c * Aª where (c and a) are constants for a given region. The theory is that as the size (A) of an environment grows, more species are able to find a local niche in which they can become adapted. As the area shrinks there are fewer livable options (not enough range to provide all essentials like foods, water and shelter) hence there are fewer species there. This explains why the Amazon Rainforest supports millions of species, whereas islands have few.
The recent spread of Man has served to artificially divide the area of a species through barriers like roads, cities and single-crop farmlands. Additionally, the global travels of Man and Commerce have unintentionally transferred many species to places where they can flourish free of natural predators while in other instances, predators were released into places where the local species had no time to evolve defenses. Those who could not adapt often went extinct.
The buildup of CO2 emissions is driving Global Warming, which causes most regions of earth to change conditions (climate, humidity, rainfall) faster than most species can adapt or migrate. Additionally, barriers by Man often prevent species from migrating to survivable places. (If adaptability is to be measured in generations, then the slower critters will be driven out while the tiny ones {bacteria and viruses} will be able to adapt fast enough to keep up)
The activities of Humans have been driving extinctions for about 50,000 years; every since we developed cooperative attitudes and efficient hunting methods. This was expressed through our advancements in tools, in building boats, in navigating and in the pioneering spirit prompting us to sail off and inhabit distant lands (thus we were able to easily hunt the local unwaryspecies). It should be noted that every new land we settled soon experienced a drastic decline in large animal species.
Tests on many ape-like creatures (Chimps, Orangutans …) show that they seem to lack this urge toward "collective problem-solving" (i.e. cooperative attitudes) which we possess. This is suspected to be the force behind the extinctions of the Neanderthals, the Devonians and possibly others in our family tree.
Concern has led to develop of many laws, formation of institutions and growth of National Parks, that work to counter the damage done by human activity. But will these be enough? On the one side there are movements by concerned groups, but on the other side there are pressures from an ever-expanding population and the notion of ourselves as "pioneers" or "opportunists" who view the world as there for the taking.
The 6th extinction started about 50,000 years ago and is now rapidly increasing. We have freed ourselves from the constraints of evolution, but we are still dependent on the earth's biological and chemical systems. By destroying them, we risk destroying ourselves!