Species Extinction: Do We Really Need It?

Our Earth is full of coloured creatures like insects, birds and cool amphibians. But why to extinct them? Are We too selfish?There have been many hundreds of anthropogenic extinctions in the last 500 years. Some examples indicate the extent of the extinction problem. In mammals, 76 species such as the Steller sea cow are extinct, 2 extinct in the wild (i.e. surviving only in captivity, SOC hereafter), and 29 possibly extinct. At least 134 birds, such as the passenger pigeon (Ectopistes migratorius) are extinct, 4 are SOC, and are 15 possibly extinct. Amphibians have been severely affected, and 159 such as the golden toad (Incilius periglenes) are extinct, one SOC, and 120 species are possibly extinct. In the case of reptiles, 21 species are considered extinct and one SOC, whereas among fishes 91 species are considered extinct.

The lack of a solid estimate of the number of living species is a major obstacle to calculating the number and rate of anthropogenic extinctions in order to compare them to background extinction rates. The IUCN considers that there are 1.8 million described animal and plant species, of which 1.3 million are animals, on which we will focus from here on. The IUCN evaluated a sample of 32,765 animal species and estimated that 9216 are endangered (28% of the animal species in the sample) including 754 extinct (and a small fraction that SOC).

[Image Detail: Described and estimated number of animal species either extinct or vulnerable to extinction based on 2008 IUCN report if all species were in the sample. Abbreviations: EX = extinct; SOC = surviving only in captivity; CR = critically endangered; EN = endangered; VU = vulnerable. These categories are the ones used in IUCN to describe different degrees of threat (CR>EN>VU).]

The estimated background extinction rate (that persisting outside of extinction waves) is one extinction per 100 years per 10,000 species or one extinction per million species years. We recently have addressed the issues of the magnitude of the anthropogenic episode. We calculated that, in the 30,000 species sample, 15 species extinctions would have been expected for that 500 year period, if there were not an anthropogenic extinction spasm. So the ~750 animal extinctions within the sample indicate an extinction rate over the last 500 years of 50 species per 100 years, per 10,000 species, and thus represent a roughly 50-fold increase over the background extinction rate. But the sample of ~30,000 species is but a tiny proportion of the described number of species.

Assuming that the proportion of extinctions among undescribed species is the same as among the 1.3 million IUCN described animal species, then the number of extinctions would be roughly 6500 species per 100 years, per 10,000 species for all animals. Thus, the estimated rate would represent a several-thousand–fold increase over the background rate of extinctions.

[Image Detail: Comparison of background extinction rates (1 species per 100 years, per 10,000 species), and those based on the IUCN 2008 sampled species and the estimated anthropogenic extinction rates (number of species per 100 years per 10,000 species). Note that the anthropogenic rates represent a several-thousand–fold increase over the background rate of extinctions.]

These rough but very conservative numbers (excluding plant extinctions and using low estimates of total species diversity) suggest that the current extinction rate is enormously higher than the background extinction rate, indicating the severity of the current extinction spasm. The ~32,000 animal species whose status has been evaluated by IUCN account for a mere 2.5% of the World’s 1,300,000 described animal species. About a quarter of the evaluated species (~8500) in the IUCN sample were listed as at risk of extinction. The most accurate estimates are those for vertebrates. Around 30% of all amphibians are endangered, followed by mammals (22%, Figure 3, birds (14%), reptiles (5%), and fishes (4%). If the vertebrate trends are even only a half of the evaluated species across the 1.3 million described animal species, the likely number of animals threatened would be ~260,000 (30 times higher than estimated by the IUCN); a high percentage of those threatened species would be invertebrates (97%). Although some claim that extinction rates in invertebrates are lower than in vertebrates, there are already available data supporting the hypothesis that invertebrate extinction rates are similar to those of vertebrates at least in some groups, such as butterflies.

[Image Detail: Patterns of distribution of all mammals considered at risk by IUCN (Modified from Ceballos et al., 2005). The column on the left indicates the number of species in 10,000 km2 grid cells.]

Clearly, even a crude estimate of population extinctions across all vertebrate groups will indicate a major biodiversity loss. What does all this mean? The losses to humanity of the sixth extinction wave are potentially catastrophic. Humanity has, as far as we know, only one set of living companions in the universe. For many, if not most human beings, other organisms are endlessly interesting – as any pet lover, butterfly collector, bird-watcher, taxonomist of mites, or gardener can testify. Every bit of diversity lost represents a diminution of interesting features of our environment. Closely connected with that interest is the beauty that most of us see in biodiversity, whether in the shimmering structural colors of a morpho butterfly’s wing, the gorgeous red and green feathers of a Quetzal, the grace of a cheetah’s sprint, or the slow-motion progress of an amoeba moving under a microscope. And, of course, there are many people who believe that we have ethical responsibility not to casually exterminate other life-forms, the products of a magisterial evolutionary process that has continued for billions of years. The sixth extinction wave thus not only threatens our esthetic and moral senses, but the very survival of civilization. It seems certain that climate disruption will greatly increase the rate of population and species extinction. Do we really need it?

[Ref: IUCN and The Sixth Extinction Crisis Loss of Animal Populations and Species BY Gerardo Ceballos]


About bruceleeeowe
An engineering student and independent researcher. I'm researching and studying quantum physics(field theories). Also searching for alien life.

One Response to Species Extinction: Do We Really Need It?

  1. Nelson says:

    Sad..why not stop them at all? I don’t find if our strategies and policies are too good. Scientists just make observation and they have nothing to do with and resolve matter. Looking for someone who is our hero.

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