Notes on verification

The 850,000-year figure matches a specific peer-reviewed estimate (Won & Hey 2005, ~0.86-0.89 Mya), but broader literature gives a wide range (0.8-2.1 million years), with many sources citing higher figures (1.5-2 Mya) as more commonly repeated. The claim is accurate but represents the low end of a contested range rather than a settled consensus figure.