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Extinction, or the disappearance of an entire species, is commonplace. Species have been forming, persisting and then shuffling off their mortal coil since life began on Earth. However, evidence suggests the number of species going extinct, and the rate at which they disappear, is increasing dramatically.
Our recent work suggests that the rate at which species are going extinct may be many times higher than previously estimated —at least for birds. The good news, however, is that recent conservation efforts have slowed this rate a lot.
Decades - Palaeontologists - Fossils - Species - Discovery
For decades, palaeontologists have used fossils to estimate how long different species persisted before dying out. The discovery of a new fossil species gives a minimum estimate of when the species might have first evolved. The absence of the same species later in the fossil record signifies its probable extinction.
Though the methods are woefully imprecise, researchers have estimated that the average lifetime of a vertebrate species is between one and three million years. Many species are at the lower end of this range, while a few species persist many millions of years longer. For comparison, our own species, Homo sapiens, has been around for less than 500,000 years.
Estimates - Conservation - Biologists - Extinction - Rates
Such estimates can be compared to what is happening now. Conservation biologists estimate current extinction rates using historic, documented extinctions. For instance, since 1500 —just after Columbus's arrival in the Americas —187 of the roughly 10,000 bird species have gone extinct worldwide.
Some simple math based on the average duration of fossil species predicts that only two to five bird species should have been lost since 1500. If the fossil data suggests a bird species will persist for three million years before going extinct, a species living in 1500 could be expected to survive for 30,000 years. In other words, a hundredfold drop.
Sort - Calculation
This is the sort of calculation that supports...
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