r/paleoanthropology

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The ‘' Out of Africa ’' model that has dominated palaeoanthropology for nearly three decades was originally based on five elements: a recent ancestry to human populations; an African origin for the ancestral population; limited or no gene flow among archaic hominins and no admixture between modern humans and Neanderthals; a marked difference between the behaviour of modern humans and archaic populations; and a major role for dispersals.

The first four of these have been significantly modified by accumulating fossil, genomic, and archaeological data. Dispersals, however, have remained central to the model, and have been extended to earlier phases of the evolution of Homo.

Here we consider the evidence for dispersals in Pleistocene hominin evolution, and place these into the broader context of comparative evolutionary biology.

We distinguish between dispersals that are essentially habitat tracking as climate or environment changes, and those conditioned by adaptive changes.

Finally, we consider the consequences of dispersals for the structure of hominin populations, emphasizing the multiple potential outcomes of dispersals, the role of density dependence in structuring rates of divergence, and the role of centre-edge models in understanding hominin diversity.

Range expansions (dispersals) and contractions have been a major characteristic of hominin evolution, and we have suggested here that these can be the product of both environmental change (habitat tracking) and the evolution of novel adaptations that expand habitat tolerance and niche space.

However, while there is no doubt that the Eurasian expansions of Homo sapiens occurring around 60 ka were very successful, and resulted in the displacement and extinction of other hominin species, the outcomes of dispersals can be highly variable.

These outcomes may range from complete replacement, absorption by the indigenous population, admixture and hybridization, or complete failure to establish a long-term population.

Twenty meters beneath a lake in northern Germany, archaeologists have found wood cut, split and shaped by people more than 10,000 years ago.

Normally, wood this old would have vanished thousands of years ago. But the Arendsee lake is unusual.

Its floor has slowly subsided as rock above an underlying salt dome dissolved and collapsed, dragging the ancient shoreline downward. Buried beneath sediment and starved of oxygen, the timbers escaped much of the microbial decay that normally destroys wood.

The pieces include a 1.6-meter wooden post bearing signs of felling and working, along with split boards as long as 1.3 meters.

Archaeologists think they may belong to some kind of Mesolithic construction (perhaps even a shelter) created roughly 3,000 years before farming communities and their longhouses reached this part of Europe.