HUMANS HAVE BEEN THE CAUSE OF OVER 100 THOUSAND EXTINCTIONS IN SPECIES ACCORDING TO SCIENTISTS

Since the start of the modern era in 1500, 777 animals have become extinct, according to the International Union for Conservation of Nature's (IUCN) Red List. Even though natural causes contributed to some of those extinctions, human activity has undoubtedly made things worse for many vulnerable species. However, the number seems small because we don't know everything about the creatures that live on our planet, which makes many scientists wonder: how many animal species have humans driven to extinction?

It is challenging to pinpoint the exact number for several reasons. To begin with, the IUCN red list dates only back to 1500, when researchers and scientists started keeping track of animal extinctions. Even with cutting-edge technology and extensive biological research, the number of extinct species in recent centuries remains difficult to determine. Furthermore, only about 5% of the known species have had their extinction risk evaluated by the IUCN. This increases the number of animals that could have become extinct and no one would have known about it.

Although mammals and birds are the most visible animal groups—when one thinks of extinct animals, they usually think of the woolly mammoth or the dodo—insects have more species than any other group, which increases their vulnerability to unrecorded extinctions. Academic quantification is complicated by the likelihood that many undiscovered species reside in tropical regions that are poorly explored.

With assistance from Philippe Bouchet and Benoît Fontaine, and Robert Cowie, a research professor at the University of Hawaii, they published a study in Biological Reviews in 2022 to determine a number. There, they proposed that since approximately 1500, between 150,000 and 260,000 of all known species may have gone extinct. The study's lead author was taken aback by the figure. "Jeez, have I messed up the calculations?" was my thought. Cowie stated to Live Science.

How was the extinction rate determined by the researchers? Initially, they examined a sample of 200 species of land snails and calculated the number of extinct snails based on prior scientific research. The number of extinctions would have occurred if all known species had continuously experienced a similar rate of extinction over 500 years, they calculated after extrapolating the data to include all known species. As a result, they estimated that for every million species on Earth, there are 150–260 extinctions annually (E/MSY). Nevertheless, the numbers varied greatly when other wildlife groups, such as amphibians and birds, were examined. They finally discovered a sweet spot.

According to Cowie, "they tend to cluster around about 100 [E/MSY]." "That seems like a more realistic value—not too conservative, not too exaggerated." According to this method, during the last 500 years, 100,000 of the approximately 2 million known species have become extinct.

John Alroy, an associate professor in the Department of Biological Sciences at Macquarie University in Australia who was not involved in the study, thinks that without knowing the initial number of species, biologists will find it extremely difficult to estimate the rates of modern extinction.

Alroy states, "We should exercise extreme caution when attempting to determine a precise figure based on the available literature." "I don't think we have a very good solution at all for the current extinction rate."

In the end, he realizes that there are far more extinctions than the 777 listed on the IUCN Red List and that the rate of extinction is only getting worse due to human activity. "The extinction rate is still very high and extremely harmful, regardless of whether it is 100 E/MSY, 20 E/MSY, or 200 E/MSY," he said in closing.