" In 1963, Leakey obtained funds from the National Geographic Society and commenced archaeological excavations with Simpson. Excavations in an area stratigraphically separate from a verified 10,000-year-old Paleoindian site were carried out by Leakey and Simpson, who believed that they had located stone artifacts that were dated 100,000 years or older, suggesting a human presence in North America much earlier than estimated.[9] "
I think Leaky later said (something like) I may be wrong.
How do we know that some relatively advanced stone age culture did not develop before the last ice age started 125,000 years ago? Or survived until the Toba eruption 74,000 years ago caused a major slide in temperatures.