A second body size diminution in taxa occurred in the Holocene between 9,000 and 7,500 ... with changing temperatures impacting thermoregulation for animals to maintain appropriate core internal ...

That's what occurred in 2002 to Paul Crutzen, a Nobel Prize‑winning chemist. The epoch spanning the past 10,000 years is known as the Holocene, meaning "all that's recent." Crutzen suggested that the ...