The extinction of large taxonomic groups, such as genera, has been extremely rare over the past 500 years and has mostly been limited to specific regions. This suggests that the current biodiversity crisis has not yet reached the scale of global catastrophes like the mass extinctions in Earth's history.

Although human activity is causing species to disappear at an unprecedented rate, many scientists and public figures refer to this process as the sixth mass extinction, comparing it to past disasters that wiped out a significant portion of life on the planet. However, a mass extinction is not simply the loss of individual species, but the disappearance of entire large groups of organisms, such as genera and families, which means the loss of unique branches on the tree of life.

During mass extinctions, it was not just individual pages, but entire chapters that vanished from the book of life. The loss of a genus means the extinction of a whole group of closely related species that evolved over millions of years. Recent studies on vertebrates have focused on alarming trends of accelerated genus extinction and have linked this to threats to humanity's own survival.

However, new research by scientists from Harvard offers a broader perspective on the issue. The study analyzed data not only on vertebrates but also on other groups of living organisms that make up the majority of the planet's biodiversity. The results were published in the journal PLOS Biology.

The researchers examined information on more than 22,000 genera of animals and plants to assess the scale of extinction at this high taxonomic level over the past 500 years. Since the year 1500, only 102 genera have disappeared, which is less than 0.5% of all groups considered.

The losses were unevenly distributed: nearly half of the extinct genera were birds (37) and mammals (21). Meanwhile, among the vast diversity of fish, amphibians, reptiles, arthropods, and plants, genus extinction was extremely rare, affecting less than 1% of the groups assessed.

The analysis also revealed a clear geographic pattern: the vast majority (76%) of extinct genera were endemics, meaning they lived in strictly limited areas. Most often, these were oceanic islands such as Hawaii, the Mascarene Islands, the West Indies, and New Zealand. Most exceptions were freshwater organisms, which also inhabit isolated ecosystems.

Additionally, the study disproved the idea of accelerating extinction rates. The data showed that the peak of genus extinction occurred at the end of the 19th and the beginning of the 20th centuries. Over the past 100 years, these rates have actually slowed down, possibly because the most vulnerable island genera have already disappeared.

Thus, while the modern biodiversity crisis remains a serious problem, it has not yet reached the scale of a true mass extinction. Nevertheless, the authors themselves emphasize that their research does not diminish the current threats.

The extinction database may be incomplete, especially for poorly studied groups, and does not account for so-called "dark extinctions"—the disappearance of species before they are scientifically discovered. Moreover, past trends, mainly driven by invasive species on islands, do not necessarily reflect future patterns, where climate change may become the main threat.