Andrew Bartlow

Historically, an estimated 0.1% of all species go extinct each year. That may not sound like a lot, but considering that there are 1.7 million species that have been scientifically identified so far, that means an annual extinction rate of 1,700 species, or more than four per day. This is known as the background extinction rate, which is the number of species that can be expected to go extinct over a period of time, based on nonhuman factors.

1. Introduction Amid an increasing global trend in emerging infectious diseases (EIDs) and outbreaks (1, 2), the need to better understand underlying drivers of EIDs has never been greater (3). The social and environmental conditions and their complex interactions that have been commonly implicated as driving EIDs include: climate and land-use change; human-wildlife interactions; shifting human demographics and behaviors including livelihood patterns; and poverty and inequality (1, 4–6).

Historically, an estimated 0.1 percent of all species go extinct each year. That may not sound like a lot, but considering that there are 1.7 million species that have been scientifically identified so far, that means an annual extinction rate of 1,700 species, or more than four per day. This is known as the background extinction rate, which is the number of species that can be expected to go extinct over a period of time, based on non-human factors.