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The rate of extinction that took place during Earth's history is referred to as the contemporary extinction rate or background extinction rate. It is the rate of extinction during the Earth's geological and biological history prior to the arrival of humans. It establishes a baseline for comparing extinction rates in the modern and present eras. It is useful in determining the frequency of extinctions that occur now versus in the past. The current activity's extinction rate has increased primarily as a result of human activities.

There are several methods that can help with current extinction rates:

1. Extinction recording over a time period (say, 400 years) in which observed extinctions and undiscovered species are adjusted for proper study.

2. Recording extinction rate over million species years: It is based on the hypothesis that one species goes extinct every million years. Another hypothesis is a mathematical interference that only one extinction occurs every million years, and then considering that if there were only one species, it would go extinct every million years.

3. It is based on calculating extinction rates based on habitat loss and studying species-area curves. It also accounts for calculating extinction rates based on species survival over time.