Camels, with their distinctive humps and remarkable ability to traverse harsh landscapes, are iconic symbols of arid regions across Africa and Asia. While their presence there suggests an origin in those areas, their true lineage traces back much further in time to a surprising continent.
The Earliest Camel Ancestors
The paleontological record indicates that the earliest ancestors of modern camelids emerged in North America. Around 40 to 50 million years ago, during the Eocene Epoch, a small mammal named Protylopus lived in the open woodlands of what is now South Dakota. This ancient camelid was roughly the size of a rabbit and possessed four-toed feet, with front limbs shorter than its hind limbs, suggesting a browsing diet of soft leaves and fruit.
Following Protylopus, approximately 35 million years ago, Poebrotherium appeared, growing to about the size of a goat. This species exhibited more traits resembling modern camels and llamas, including longer, more slender limbs suitable for running on open terrain, though it still walked on hooves rather than padded feet. Other camelid genera, such as the “tip-toed” Stenomylus and the long-necked Aepycamelus, which developed padded feet, continued to evolve in North America through the Miocene epoch, adapting to changing environments that saw forests transition into grasslands.
Migration from North America
The geographical spread of camelids from their North American birthplace was a gradual process influenced by significant geological and environmental shifts. The ancestor of modern camels, Paracamelus, embarked on a migration into Eurasia via the Bering Land Bridge during the late Miocene, approximately 6 to 7.5 million years ago. This land bridge, now submerged, connected what is now Siberia and Alaska, providing a pathway for biological dispersal between the continents.
Environmental changes, including periods of increased cooling and the expansion of steppe lands, likely drove these movements. Later, around 3 to 5 million years ago during the Pliocene and Pleistocene epochs, some North American camelids also spread southward into South America through the newly formed Isthmus of Panama, leading to the development of unique lineages there. Ultimately, camels became extinct in North America, with the last native species, Camelops hesternus, vanishing roughly 11,000 to 13,000 years ago, coinciding with the arrival of humans and the extinction of many other large mammals.
Divergence into Modern Camelids
Following their migrations, camelid lineages diversified considerably across different parts of the world, resulting in the distinct groups observed today. The evolutionary split between Old World camelids and New World camelids occurred approximately 11 to 16.3 million years ago. Old World camelids, which include the one-humped dromedary (Camelus dromedarius) and the two-humped Bactrian camel (Camelus bactrianus and Camelus ferus), adapted to the arid and cold desert environments of Africa and Asia.
These Old World species developed specialized features, such as humps that store fat, serving as an energy reserve in areas with limited food and water. This fat storage also aids in thermoregulation, allowing them to release heat more efficiently from their bodies in hot conditions. In contrast, New World camelids, comprising llamas (Lama glama), alpacas (Vicugna pacos), guanacos (Lama guanicoe), and vicuñas (Vicugna vicugna), evolved in the high-altitude prairies of South America and do not possess humps.
The Role of Domestication
Human interaction played a significant role in shaping the distribution and utility of camelids. Domestication of South American camelids, llamas and alpacas, began around 6,000 to 4,000 years ago in the Andes region, primarily in the Peruvian central highlands. This involved herd protection and selective breeding.
In the Old World, dromedary and Bactrian camels were domesticated later, likely between 3,000 and 1,500 BCE. These large camel species became highly valued for transportation, revolutionizing trade routes like the Silk Road, and providing resources such as milk, meat, and wool. Human intervention expanded their populations, geographical reach, and led to the development of specific traits for various societal roles.