It begins in Brazil, in a landscape of caves and ancient bones, where the question started long before anyone had a genome to analyze.

The Caves of Lagoa Santa and What They Held

The Lagoa Santa region of the state of Minas Gerais in central Brazil is a landscape of limestone karst — a terrain shaped by the slow dissolution of rock by slightly acidic groundwater over millions of years.

The result is a landscape pocked with sinkholes, threaded with underground rivers, and riddled with caves.

Some of those caves have entrances large enough for human habitation.

Some have passages small enough that a person must crawl to enter.

And some of them have been accumulating the remains of the animals and people and plants that lived in and around them for the better part of twelve thousand years.

The archaeological potential of this landscape was recognized by European researchers in the nineteenth century, when the Danish naturalist Peter Wilhelm Lund — who had come to Brazil in 1833 to study its natural history and who spent years exploring the region’s caves — began finding the bones of extinct Pleistocene megafauna mixed with the remains of apparently ancient humans.

Lund’s finds were significant enough to generate international scientific discussion.

Here were human bones associated with the bones of creatures that had died out at the end of the last Ice Age — giant ground sloths, horses, mastodons, and other megafauna that had vanished from the Americas roughly ten to twelve thousand years ago.

The implication was that these ancient people had lived alongside those creatures, placing them at a remarkable depth of time.

The Lagoa Santa skeletal material that Lund and subsequent researchers excavated was distinctive in ways that would generate controversy for the next century and a half.

The skulls of these early people were, in measurable morphological terms, different from the skulls of later Native American populations.

They were characterized by longer, narrower brain cases, more prominent brow ridges, and facial proportions that led researchers to describe them with terms like “gracile,” “long-headed,” or by the technical measurement term “dolichocephalic.” Later Native American populations, by contrast, tended toward skulls that were broader and more rounded — a different set of measurable proportions.