Darwin’s “Giant Llama” and Legacy of Ancient Megafauna


Nearly two hundred years ago, an epic voyage shaped the views of a young naturalist.  Traveling aboard H.M.S. Beagle through South America from 1832-35, as well as over land, Darwin took in endemic flora and fauna which helped shape the theory of evolution by natural selection.  In Argentina, Darwin uncovered the bones of bizarre ancient megafauna which had long since disappeared.  Though it’s unclear what may have led to the animals’ demise, climate change and human encroachment may have played a role.

Are there lessons to be learned, or will we simply repeat past mistakes?  To be sure, Darwin would not have been surprised by the notion that the environment is changing; however, he might have been non-plussed by the drastic speed at which this is occurring today.  Though climate has certainly shaped the course of evolution, the rapid pace of warming has put modern-day animals resembling ancient megafauna to the test.

Such issues were on my mind as I traveled to Argentina late last year in conjunction with a book project retracing Darwin’s voyage.  The young naturalist gathered fossils here belonging to an astonishing creature called Macrauchenia, which “resembled a bulky camel without a hump, with a long neck like that of a llama and a short trunk for a nose.”  A plant-eating mammal initially described as a “giant llama,” Macrauchenia would have used its long neck to reach leaves on plants or bushes while grazing in Patagonia.  Researchers believe Macrauchenia “would not have looked very much like anything alive today.”

Though Darwin thought the creature may have been a prehistoric llama, Macrauchenia was nine feet in length, weighed more than 2,000 pounds and wasn’t very agile.  Moreover, when scientists observed Macrauchenia had three toes, as opposed to two-toed camels, the llama hypothesis had to be abandoned.  Scientists now believe the animal belonged to an extinct group of mammals called litopterns, and Macrauchenia’s closest living relatives are horses, rhinos and tapirs.  Macrauchenia lived side by side with other megafauna during the Pleistocene; however, the large creature died out approximately 12,000-10,000 years ago, perhaps due to warming and climate change.

Examining the bones, Darwin was struck by apparent similarities between extinct Macrauchenia and living mammals of South America, prompting him to wonder if “one species changes into another,” a train of thought which would eventually lead him to come up with the theory of evolution.  For more on these questions, I headed to the “Bernardino Rivadavia” Argentine Museum of Natural Sciences in Buenos Aires.  On a sweltering summer day, I observed panel façades outside the museum featuring emblematic animals such as guanaco, a wild relative of the domesticated llama.

Paleontologist Agustín Martinelli remarked the museum did not hold any original fossils recovered by Darwin.  The scientist added, however, that he would be interested in exhibits dealing with Darwin’s legacy, though trying political and economic conditions were an obstacle.  When we spoke, right-wing Javier Milei had just won the presidential election, but had not yet assumed power.  When I asked if Milei, a climate change denier, might cut funding to scientific research and museums, Martinelli answered “of course we are afraid.”  Meanwhile, even as the city heats up outside, curators lack funds to maintain proper indoor temperatures, which in turn affects the museum’s holdings.

“Bernardino Rivadavia” Argentine Museum of Natural Sciences

The discussion turned back to wildlife past and present: unlike Macrauchenia, Martinelli did not believe guanacos were in imminent danger of extinction, though he acknowledged difficulties.  At one time, he remarked, the animals could be observed in the vicinity of Buenos Aires itself, though now the animal inhabits areas farther from human settlement.  Efforts to reintroduce guanacos to ecological reserves through “re-wilding,” meanwhile, have proven controversial.

Turning back to ancient conditions on the pampas or plains, I asked about the 900-pound saber-toothed cat, known as Smilodon populator, which preyed on Macrauchenia.  Smilodon thrived between 25,000-10,000 B.C., but then died out, prompting scientists to wonder whether the creature was killed off by climate change or humans.  Though people overlapped with Smilodon and other megafauna for a few thousand years, it appears the creatures all disappeared in a 300-year time frame.  Rather than succumbing to a human “blitzkrieg,” some researchers believe megafauna was decimated by abrupt warming, which led to changes in vegetation.  Other scientists, however, believe human predation dealt the crucial blow.

Given increasing rates of extinctions amidst global warming, Darwin would probably be interested in figuring out what happened to megafauna such as Smilodon.  In 1846, years after the voyage of the Beagle, naturalist Francisco Javier Muñiz reached out to Darwin, who by this point had become a celebrity in Argentina.  Muñiz had found a nearly complete saber-toothed cat skeleton and wanted to sell it.  Though Darwin sought to arrange a purchase, the sale never occurred.  “Muñiz was a doctor,” Martinelli remarks, “but he could be considered the first Argentine naturalist.”  Martinelli adds his museum holds fossils uncovered by Muñiz, as well as an original letter sent by Darwin.

In contrast to the Pleistocene age of Smilodon, pumas are now apex predators on the pampas.  Historically, pumas preyed on guanacos, but when the latter were hunted or driven away by ranchers, the felines were forced to find an alternative source of food.  It was then, Martinelli says, that pumas began to prey on livestock, which in turn resulted in ranchers hunting the wild animals.  Indeed, in the Patagonian province of Chubut, pumas are considered a pest.

Upstairs, Martinelli guides me to an exhibit entitled “Giants of the Argentine Pleistocene.”  Taking in skeletons of giant ground sloths, I am non-plussed.  I mused that in “Pleistocene Park,” Russian scientists are trying to postpone climate change by resurrecting an ancient biome as well as cloned wooly mammoths.  “Yes,” Martinelli chuckled, “but the Siberian expanse is practically infinite, whereas in Argentina, I don’t think that would be possible.  In the pampas, a lot of space is taken up by soy, corn, and livestock production.”  In any case, though scientists have managed to extract some collagen from megafauna, they lack sufficient DNA.

Presently, we came to a life-size model of hunters spearing a Glyptodont.  Darwin uncovered the creature in Argentina, a gigantic armadillo the size of a Volkswagen which thrived some 10,000 years ago.  The naturalist noted the similarity between Glyptodont and current day armadillos, and wondered why so many animals had gone extinct, only to be replaced by similar ones?  Perhaps, he reasoned, newer species were more suited to a changing environment.  Today, Argentine scientists organize forums to raise educational awareness about Glyptodont.  The creature has become an icon, Martinelli says, with “paleo-artists” sculpting the animal in clay or recreating its likeness through recycled cardboard.

I have a few days before I must head south to join Darwin200 initiative, a scientific expedition retracing the naturalist’s voyage aboard the Beagle.  Walking downtown, I come upon Milei’s inauguration: the crowds are in a frenzy amidst stultifying heat.  It is an ironic scene, since Argentina is projected to experience a range of climate impacts ranging from extreme rain, droughts and temperature increases.  In Puerto Madryn, a Patagonian town in Chubut province one hour away by plane, I realize my itinerary has been foiled: though I had planned to visit La Esperanza nature reserve through the Natural Patagonia Foundation, a gigantic blaze near the lodge had made road travel impossible.  Though Darwin wrote perceptively about weather in Argentina, noting drought conditions followed by torrential rains, he would probably be concerned about Patagonia, which is projected to experience both drought and extreme rainfall.

Puerto Madryn

Improvising, I take a shorter day trip to Punta Tombo Nature Reserve, where I observe skittish guanaco near the trail.  Winter in Patagonia has become warmer and less severe over time, my guide remarks, whereas summer has become longer and windier.  As the sun beat down mercilessly, I approached a park ranger, who remarked that wildlife was secure at Punta Tombo, though elsewhere guanaco were hunted illegally.  A few days later, I got word it was safe to travel to La Esperanza.  However, a tremendous storm had washed out the road, making it necessary for our jeep to slog through rivers of water.

Guanacos at Punta Tombo
Washed out road heading to La Esperanza

As we neared the nature reserve, my heart sank: as far as the eye could see, landscape was charred and an acrid smell hung in the air.  At the lodge, I met Yaco Conchillo, a rugged young park ranger sporting a gaucho-style beret.  Accompanied by a farm dog named Viejo, we drank copious amounts of yerba maté tea as the wind howled outside the house. “To be an effective ranger,” he remarked, “you need to be well-prepared both physically and psychologically.  Patagonia displays a hostile climate including storms, rains, and fires, as you just observed.”  Though rain had decreased overall, he said, storms had become more intense.

Charred landscape around La Esperanza
The lodge at La Esperanza

Conchillo provided harrowing details of the fire, which lapped close to the lodge.  The blaze, which he believes started by natural means, commenced at midday, and a few firemen arrived two hours later.  By mid-afternoon, however, the fire had become immense.  Fanned by winds, the fire eventually devastated half of La Esperanza.  Such fires may occur in summer, though Conchillo thinks blazes are now occurring more frequently.  Indeed, just one year earlier, another destructive fire in the area occurred, and the countryside had just started to recover when the new blaze erupted.

Touring the refuge on foot the next day, we observed guanacos which kept their distance.  It seems the animals managed to escape the blaze by heading to the coast, Conchillo says.  However, less mobile wildlife such as lizards did not fare as well, and loss of bird nests and chicks was “incalculable.”  Stepping over a dead armadillo, Conchillo said he monitors pumas via camera traps and ensures hunters don’t enter the vast reserve, which encompasses both coastline and varied inland terrain.  The work can be perilous, and Conchillo once spied three men through his binoculars disposing of a guanaco.  When he approached, the men left their dead prey and took off in a hurry.

Time is running short before I must meet up with the Darwin expedition, and as I return to Puerto Madryn, I spot my vessel anchored in the bay.  Hoping to contextualize the past leg of my Argentine journey, I arrange a meeting with Rolando González-José, a biologist specializing in physical anthropology.  Weighed down by my suitcase, I pass an anti-Milei political protest before arriving at a local café.  “I believe megafauna succumbed due to the double blow of climate change and hunting,” González-José remarked.  In the specific case of Patagonia, what may have happened was that human population increased to such a degree that Darwin’s ancient creatures were placed under incredible pressure.

If anything, wildlife will continue to be pushed to the limit today, since climate change in this part of the world gives rise to shocking weather events, be it extreme wind, drought and rain.  I wanted to discuss the role of fire and mentioned my shock at the blaze which had engulfed La Esperanza.  To be sure, not all fire should be considered negative, and indeed Darwin regarded fire as one of the most important discoveries made by humanity.  Now, however, researchers wonder whether we have entered a new “Pyrocene” era, and González-José was concerned about the increase in fires due to human activities and climate change.

Given such environmental pressures, what was the outlook likely to be under climate-denying Milei?  Employing a somewhat ironic euphemism, my companion said the president might try to “asphyxiate” funding to the sciences, which would certainly be damaging.  However, even though González-José was worried, the expert explained that Argentina displayed a long tradition of scientific research going back hundreds of years, which might prove difficult to uproot or dismantle.  “We even have early figures like Muñíz, who corresponded with Darwin,” he said.  At the mention of Darwin, I glance out the window, noting the tall sailboat out in port which will take me on the next leg of my expedition.


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