Camelid evolution: from North American origins to the Andes and genomics

We instinctively associate llamas and alpacas with the South American Andes, and dromedary and Bactrian camels with the deserts of Africa and Asia. Yet the fossil record and modern evolutionary genomics reveal a striking biogeographical paradox: the family Camelidae originated in North America more than 40 million years ago and remained restricted to that continent for over three-quarters of its evolutionary history. [1, 2] Only within the last several million years did its two major tribes disperse across opposite intercontinental land bridges—the Bering Land Bridge into Eurasia and the Isthmus of Panama into South America—before vanishing completely from their North American homeland at the close of the Pleistocene.

Eocene origins and the Miocene radiation in North America

The earliest representatives of the suborder Tylopoda and the family Camelidae appeared in the open woodlands and plains of North America during the middle Eocene, roughly 45 to 40 million years ago. One of the best-known early fossil genera is the Oligocene browser Poebrotherium (~35 million years ago), a slender animal about the size of a small sheep or gazelle that already displayed an elongated skull, a narrow upright neck and cursorial limbs, while transitioning toward functional two-toed support on the third and fourth digits.

During the Miocene epoch (23 to 5 million years ago), global cooling and the spread of vast North American grasslands triggered a remarkable adaptive radiation of camelids. It was in these Miocene savannas and steppes that the hallmark anatomical features of modern llamas evolved: the fusion of the third and fourth metapodial bones into a single cannon bone whose distal ends splay outward in a characteristic Y-shape, the development of broad fibro-elastic plantar foot pads suited for loose sand and rocky substrates, the energy-saving ipsilateral pacing gait, and high-crowned (hypsodont) cheek teeth capable of withstanding abrasive silica-rich grasses. Miocene and Pliocene North America hosted a diverse array of camelids, ranging from swift gazelle-like forms such as Procamelus to giraffe-necked treetop browsers (Aepycamelus) and giant Ice Age forms standing over three metres tall (Titanotylopus).

The great divergence: Beringia, Panama and Pleistocene extinction

Palaeontological evidence and whole-genome molecular clocks indicate that the two living tribes of camelids—Camelini (Old World camels) and Lamini (New World camelids)—diverged from a common North American ancestor between 16 and 11 million years ago during the middle to late Miocene. [1] In the late Miocene and Pliocene, these two lineages embarked on transcontinental migrations in opposite directions:

• The northern route across Beringia into Eurasia and Africa (tribe Camelini): Between 7 and 5 million years ago, when lowered sea levels exposed the Bering Land Bridge, ancestors of the tribe Camelini such as Paracamelus crossed from Alaska into eastern Siberia. Expanding across the Eurasian steppes into the Middle East and North Africa, this lineage gave rise to the three extant Old World species: the one-humped dromedary (Camelus dromedarius), the domestic two-humped Bactrian camel (Camelus bactrianus) and the critically endangered wild Bactrian camel (Camelus ferus). [1]
• The Great American Biotic Interchange southward (tribe Lamini): Around 3 million years ago, tectonic uplift and volcanic activity closed the Isthmus of Panama, uniting North and South America. During this landmark biogeographical event—known as the Great American Biotic Interchange—members of the tribe Lamini, notably populations of the genus Hemiauchenia and later Palaeolama, migrated south into South America. [1, 2]

In an evolutionary twist, after successfully colonising Asia, Africa and South America, every camelid species that remained in North America—including the iconic western camel Camelops hesternus, preserved in abundance at the Rancho La Brea tar pits, and North American species of Hemiauchenia—went extinct between 12,000 and 10,000 years ago at the Pleistocene–Holocene boundary, driven by rapid post-glacial climate shifts and hunting pressure from arriving Palaeo-Indian populations.

Andean radiation: emergence of the guanaco and the vicuña

Evolutionary and biogeographical timeline of the family Camelidae

Geological epoch	Approximate age	Evolutionary milestone and representative taxa	Geographical region
Eocene – Oligocene	45 – 30 million years ago	Origin of early tylopods and primitive camelids (Poebrotherium); loss of functional lateral toes.	North America
Middle to Late Miocene	17 – 11 million years ago	Evolution of plantar pads and pacing gait; divergence between tribes Camelini and Lamini. [1]	North America
Late Miocene – Pliocene	7 – 3 million years ago	Camelini (Paracamelus) cross Beringia to Eurasia; Lamini (Hemiauchenia) cross Panama to South America.	Beringia / Isthmus of Panama
Early Pleistocene	~2 million years ago	Divergence in South America of the two extant wild genera: Lama (guanaco) and Vicugna (vicuña). [1, 2, 3]	Andes and Southern Cone
Terminal Pleistocene	12,000 – 10,000 years ago	Complete extinction of North American camelids (Camelops, Hemiauchenia) and Palaeolama.	The Americas
Middle Holocene	7,000 – 6,000 years ago	Andean domestication of the llama (Lama glama) from the guanaco and alpaca (Vicugna pacos) from the vicuña. [1, 5]	Central Andes

Once established in South America, descendants of Hemiauchenia encountered diverse habitats across the rising Andean cordillera and Patagonian steppes, splitting roughly 2 million years ago into the two wild genera alive today: the guanaco (Lama guanicoe) and the vicuña (Vicugna vicugna). [1, 2, 3] The guanaco evolved as a large, ecologically versatile herbivore (90–140 kg) capable of thriving from sea level in Patagonia and the Atacama Desert up to elevations exceeding 4,000 metres. [2] The vicuña, by contrast, became an extreme high-altitude specialist of the puna above 3,500 metres: it retained a small, gracile frame (40–60 kg), evolved an ultra-fine insulating fleece and developed continuously growing lower incisors with labial enamel—convergent with rodent incisors—to clip tough bunchgrasses close to the ground. [3] Explore the resulting physiological adaptations in our guide to scientific facts about llamas.

Conserved karyotype (2n = 74), domestication and introgression

For decades, zoologists debated the exact ancestry of the domestic llama and alpaca: competing hypotheses proposed that both descended from the guanaco, that the alpaca was a llama–vicuña hybrid, or that each descended from a separate wild ancestor. Resolving this question was complicated by a remarkable cytogenetic trait: all living camelids—both the four South American species and Old World camels—share an identical diploid chromosome number (2n = 74) with nearly indistinguishable chromosome banding patterns. In the Andes, all four South American camelids can interbreed and produce fertile offspring, such as the huarizo (born from a male llama and a female alpaca) and the paco-vicuña (alpaca × vicuña). [1, 5]

In 2020, a landmark whole-genome sequencing study by Fan and colleagues settled the phylogenetic debate. [1] Comparing genomes across wild and domestic populations throughout South America, the researchers confirmed two independent domestication events initiated by Andean pastoralists 6,000 to 7,000 years ago: the llama (Lama glama) was domesticated from northern guanaco populations (Lama guanicoe cacsilensis), whereas the alpaca (Vicugna pacos) was domesticated from the northern vicuña (Vicugna vicugna mensalis). [1]

Crucially, the genomic analysis also explained why earlier mitochondrial DNA studies had yielded conflicting signals: roughly 36% of the modern alpaca's nuclear genome derives from asymmetric hybridisation (introgression) from the llama occurring approximately 400 to 500 years ago. [1] This genetic admixture coincides with the 16th-century Spanish conquest, when catastrophic population crashes among both Indigenous herders and camelid flocks dismantled pre-Hispanic breeding management that had kept llamas and alpacas strictly separated by function and fibre quality. To learn how to distinguish the four species today, see our identification guide to llamas, alpacas, vicuñas and guanacos, and explore the archaeological record of Andean herding in llamas in Andean history.

Frequently asked questions about camelid evolution

• Why did camelids go extinct in North America if they evolved there? At the end of the last Ice Age around 11,000 years ago, rapid restructuring of Pleistocene ecosystems combined with hunting by arriving human populations wiped out North American megafauna—including Camelops and Hemiauchenia—while relatives that had earlier migrated to Eurasia and South America survived.
• Which wild animals are the ancestors of the llama and the alpaca? Whole-genome sequencing confirms that the llama was domesticated from the guanaco (Lama guanicoe) and the alpaca was domesticated from the vicuña (Vicugna vicugna), followed by roughly 36% llama gene flow into alpacas after the Spanish conquest. [1]
• Can a llama and an alpaca produce fertile offspring? Yes; because all South American camelids share a conserved karyotype of 74 chromosomes (2n = 74), crosses between llamas and alpacas produce fertile hybrids known as huarizos. [1]