Multiregional Hypothesis

From EvoWiki

The Multiregional Hypothesis (also known as the Regional Continuity Model) proposes that H. erectus, H. heidelbergensis, and H. ergaster remained a single, interbreeding species, (and the taxon H. erectus has priority) despite their geographic distance, and gene flow between distantly located populations, through intermediate populations, prevented speciation. Under this hypothesis, modern human anatomy and behavior occurred all over Africa and Eurasia, so modern humans evolved in all three regions. Following the multiregional hypothesis, the neandertals (H. neanderthalensis) were simply an archaic version of H. sapiens and are ancestral to modern humans (Jacobs, 2000a, Thorne and Wolpoff 1981, Wolpoff et al. 1994).

To get more context, check the page on the competing (and today preferred) Out of Africa hypothesis that proposes a number of emigration waves from Africa, each of which (mostly) replaced previous populations.