1856 saw the discovery of the Neanderthal skull, 1859 the acceptance of the association of humans and extinct animals, and the same year the publication of Charles Darwin's
Origin of Species
, his theory of evolution and natural selection.
Evolutionary theory provided the conceptual framework for studying not just 6,000 years of human history and prehistory, but an infinite prehistoric landscape that stretched back thousands of years into the remote past.
Archaeologists have studied this long time scale ever since.