According to the American Fun Science website on July 21st, humans are very good at eliminating wild animals. From the dodo bird to the golden toad and toad, and then to the Tasmanian tiger, many species have disappeared because of us. But how many animal extinctions have been caused by humans? Scientists do not have a definite answer to this question, and the number is difficult to estimate, but it may reach hundreds of thousands. Let's start with the confirmed extinction. According to the IUCN Red List, a total of 777 species of animals have gone extinct since the world entered modern times in 1500. Some of these species may be naturally extinct; However, given the impact we have had on nature, especially in the past 500 years, humans may have played a role in the extinction of almost all, if not all, of these species. Humans have been causing species extinction for thousands of years, but at that time there were no scientists studying these phenomena. Due to the high uncertainty of today's extinction rates, we will first focus on the situation over the past 500 years. The International Union for Conservation of Nature only assesses the extinction risk of 5% of known species worldwide, so there are certainly many unrecorded species that have gone extinct. In 2022, a study published in the journal Biological Research showed that up to 150000 to 260000 known species may have gone extinct since around 1500. These numbers are too large, which surprised the lead author of the research report, Robert Coyle, a research professor at the University of Hawaii. He said, 'I was thinking, did I miscalculate?' Kao Yi didn't miscalculate, but his estimation carried a clear warning. To calculate the specific number, his team randomly selected 200 samples of terrestrial mollusks and used previous scientific research and expert consultation to determine how many of them were already extinct. Then, they calculated how many species would go extinct if all known species had been facing similar extinction rates for 500 years. They calculated a species extinction rate of 150-260 E/MSY, which means that for every 1 million species on Earth, there are 150-260 species going extinct each year. Kao Yi also studied the extinction rates of other wild animal populations, including amphibians and birds. The estimated number is between 10-243 E/MSY, but there is an optimal value. Kao Yi said, "They tend to be concentrated around 100 E/MSY. I think this value is reasonable, not overly conservative, nor overly exaggerated." If calculated based on 100 E/MSY, then in the past 500 years, about 100000 out of approximately 2 million known species have become extinct. However, this does not include unknown animal species. A study published in the journal Biology at the Public Library of Science in 2011 estimated that there are approximately 7.7 million animal species. If this number is used and assuming an extinction rate of 100 E/MSY over 500 years, this website estimates that the number of animal species caused by human extinction is 381150. This is a rough estimate and needs to be treated with caution. John Olroy, Associate Professor in the Department of Biological Sciences at Macquarie University in Australia, is dedicated to quantifying species diversity and extinction. He told this website that he believes it is almost impossible to calculate the modern rate of species extinction. Olroy said, "To determine a number based on existing literature, we should be extremely cautious. I don't think we have a good way to calculate the current extinction rate." Olroy said that to understand the overall rate of species extinction, researchers first need to figure out how many species there are. There are many wild animals in the world that are still unknown to science and often concentrated in areas that have not been fully studied, such as the tropics. Even worse, there are more types of insects than any other animal; But compared to larger animals such as mammals and birds, we know very little about them. (New Society)