The tropical and subtropical conditions of much of South America are, from the perspective of DNA preservation, among the most challenging possible.

The early South American skeletal material from sites like Lagoa Santa is therefore among the most difficult ancient DNA material to work with.

The warm, humid conditions of the Brazilian cerrado and the cave environments where much of the skeletal material was found are not conducive to long-term DNA preservation.

Researchers working with this material have had to develop and apply particularly sensitive methods for extracting and sequencing the small, degraded quantities of DNA that survive.

Despite these challenges, the past decade has produced a series of ancient genome studies that have fundamentally changed what can be said about the genetic history of early South Americans.