To understand what the Anzick burial means, you first have to understand the world that the child lived and died in.

It was not the world we know.

Thirteen thousand years ago, the ice was retreating.

The great Laurentide Ice Sheet, which had covered most of Canada and the northern United States under a layer of glacial ice sometimes more than a mile thick, was melting back northward.

The climate was warming, but the change was uneven and sometimes abrupt — the world of 13,000 years ago was a world in climatic transition, oscillating between cold and warmer periods, still nothing like the temperate conditions that would prevail once the glaciers were fully gone.

The landscape of what is now Montana, 13,000 years ago, was a mosaic of environments shaped by the glacier’s recent presence and ongoing retreat.

Glacial lakes occupied low-lying basins.

Meltwater rivers carved through the terrain, depositing the sediments that would eventually become the ranching and farming country of today.

The vegetation was different from anything currently found in the region — a mix of species adapted to the transitional climate, with boreal forest types and open parkland elements that no longer coexist in modern ecosystems.

The animals were extraordinary by modern standards.

Woolly mammoths still walked the continent, though their population was declining.

American mastodons occupied different ecological niches than mammoths, preferring browsing in wooded areas over the open grassland grazing that mammoths preferred.

Horses — true wild horses, now extinct in North America — moved in herds across the landscape.

Giant ground sloths, some as large as modern elephants, still pulled at vegetation.