Posted by: Rob Viens | October 16, 2012

The Guanaco Family Tree

Yet again, Darwin had a chance to meet one of the iconic South American large mammals – this time it was the guanaco:

“Again I walked to Punta alta to look for fossil bones: on the road I crossed the track of a large herd of the Guanaco or American Camel.— the marks were as large as a cow, but more cloven. We laid in a good stock of fresh provisions for sea; as 6 deer were shot & great numbers of fish caught.” (Oct 16)

As he notes, the Guanaco is a New World camel (family Camelidae) – one of four species including lamas and alpacas.  There are 2 species of Old World camels, too –  the dromedary and Bactrian camel (which are easy to tell apart by the number of “humps” they have – one and two respectively).

Guanaco (from Wikipedia Commons):

guanaco

So how did all the world’s camels end up in South America and Africa/central Asia – two locations separated by half the globe?  Well, that question is what makes the story of camels so interesting.  Camels evolved in North America about 45 million years ago.  (In fact, some of the best early camel fossils in the world are found just south of me in the state of Oregon.)

Fossil camel skull from the John Day Fossil Beds in Oregon (from stevelewalready)

camel fossil from John Day Fossil Beds

For the next 40+ million years camels remained in North America where they thrived. But about 2-3 million years ago all that changed.  About that time the Bering land bridge connected North America to Asia and the Isthmus of Panama formed linking South America to North America.  What ensued was a mass migration of a lot of different species both to and from North America to other parts of the world (including horses and elephants and ground sloths). Camels migrated outward and covered the globe.

As modern times approached, camel numbers began to decline – possibly as a result of human hunters or maybe climate change.  By the Holocene (the last 10,000 years) only the three main populations (Bactrian camels, dromedaries, and New world camels (lamas, alpacas and guanacos)) remained – separated by two great oceans.  The camels of North America went extinct.

A cool fact about guanacos – they can be found from sea level up to 13,000 feet in the Andes. Populations that live at higher elevations have a hemoglobin count that is 4x that of humans – an adaptations to the lower oxygen levels at those higher elevations. In addition, because the main predator of the guanaco is the puma, these New World camels have evolved skin on their necks that is twice the thickness of their “typical” skin – a sort of leather body armor.

PS – For those that be interested in a “course” on evolution and genetics that is somewhat adaptable to any level of interest, I’d recommend checking out the free online course on the Coursera website.  This course lasts for 10 weeks and includes about half a dozen video lectures each week (typically about 10-15 minutes each). You can just take it for fun – watching the videos that interest you, or you can also take some weekly “quizzes” and a couple of tests and receive a “certificate of completion” at the end. It all free and adaptable to whatever you want to get out of it.  Take a look at https://www.coursera.org/course/geneticsevolution

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Responses

  1. Camels in North America! I had absolutely no idea, and I’ve had alpacas for years.

  2. […] The Ona and Hauch peoples were primarily a land-based people who lived on the Isla Grande de Tierra del Fuego (the largest island in Tierra del Fuego).  Although they overlapped, the Ona were found mostly found on the northern and central parts of the Island , while the Haush primarily on the southeastern coast of the island. Both tribes were primarily hunters and lived off the only real large game on the island – the guanaco (a type of camel – see The Guanaco Family Tree). […]

  3. […] For more on rheas (Darwin’s ostriches) and guanacos (New World camels) see A Wish for Wing that Work and The Guanaco Family Tree. […]


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