It has been hypothesized that the Toba supereruption about 74,000 years ago destroyed much of India's central forests, covering it with a layer of volcanic ash, and may have brought humans worldwide to a state of near-extinction by suddenly plunging the planet into an ice-age that could have lasted for up to 1,800 years. If true, this may "explain the apparent bottleneck in human populations that geneticists believe occurred between 50,000 and 100,000 years ago" and the relative "lack of genetic diversity among humans alive today".