Mammalian species are known to last an average of 2.5 million years before being snuffed out, but nobody had been able to figure out why. The reason, it turns out, may be linked to regular wobbles in Earth’s orbit.
Jan van Dam from Utrecht University in the Netherlands and colleagues reached this conclusion after studying the fossil record of rodents from central Spain over a 22-million-year span. This showed a link between rodent extinction events and the climate record.
Changes in the Earth’s tilt and the shape of its orbit lead to climate cycles of around 1.2 and 2.4 million years. At their extremes both these…
