Question

Over the past 400 years, humans have documented the extinction of more than ________ species. This modern rate of species extinction is estimated to be ________ the normal extinction rate seen in the fossil record.

A. 10,000; at least 1 million times greater than
B. 400; about double
C. 1,000; over 100 times greater than
D. 100; about the same as

Answer 1

Humans have documented the extinction of over (C) 1,000 species in the past 400 years, with the current extinction rate being over 100 times greater than the fossil record's background rate.

Step-by-step explanation:

Humans have recorded the extinction of around 1,000 species throughout the last 400 years. This modern rate of species extinction is estimated to be over 100 times greater than the normal extinction rate seen in the fossil record. Therefore, the correct answer to the question is C. 1,000; over 100 times greater than.

The background extinction rate, which is the rate of species extinction during periods without extraordinary extinction pulses, is estimated to be about 1 per million species years (E/MSY). In comparison, current estimates of extinction rates are as high as 100 E/MSY. Looking ahead, the projected extinction rate by the end of the century is an even more alarming 1,500 E/MSY. This rapid increase in extinction rates correlates with human activities and is a primary cause for the ongoing biodiversity crisis.