The ancient origins of the guan reveal a complex history of South American evolution.

Nature · Published 3 October 2026 Swipe more like this →

In short: Guans are the largest group within the Cracidae bird family, primarily inhabiting northern South America and southern Central America. While they appear as a cohesive group, their evolutionary path is marked by ancient divergences, relictual distributions, and a mysterious origin point rooted in the northern Andes during the Oligocene epoch.

The evolutionary history of guans is remarkably well-understood thanks to comprehensive analyses of morphology, biogeography, and DNA sequences. Evidence suggests that the group originated in the northern Andes, likely in the region of modern-day Colombia or Ecuador. Their initial radiation is estimated to have occurred roughly 40 to 25 million years ago, during the Oligocene. The two most basal lineages, Penelopina and Chamaepetes, diverged later, around 20 to 15 million years ago during the Burdigalian.

The group's expansion was defined by a southward migration across tropical South America. However, this spread was not uniform. The present-day distribution of piping-guans, specifically the genus Aburria, appears relictual. During the Late Pliocene, climate-driven habitat fragmentation forced these birds into isolated refugia. This process was potentially exacerbated by competition with the more diverse and adaptable Penelope genus, which likely limited the range and success of other lineages as they navigated a changing landscape.

Taxonomically, the guans are distinct from the horned guan (Oreophasis derbianus), which is an ancient, monotypic cracid with no close living relatives. While the subfamily classification often includes chachalacas, the horned guan remains excluded from this grouping. The complexity of these relationships highlights the unique evolutionary pressures faced by Neotropical birds, where environmental shifts and inter-species competition have shaped the diversity we observe today. Understanding these patterns provides a window into the broader ecological history of the South American continent.

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