Have you ever been charged a fortune for guacamole with your chips?
Well, you can blame sloths for that.
Avocados, the primary ingredient in guacamole, are something of an oddity in the plant world. Believe it or not, avocados are considered fruit due to the presence of seeds within each avocado. Speaking of seeds, they are massive and far too large for most animals native to the avocado’s home of Mexico to consume them. I mean you can eat the seed, but it would get stuck on one end…or the other. Like most fruits, avocados rely on animals to spread their seeds to new locations, yet for avocados, it seems that no animal would be up to the job. Unless you consider that avocados evolved to accommodate a much different crowd of animals.
Avocados evolved during the Cenozoic era in what is now South and Central America. During this time, avocados were found in areas populated with numerous species of herbivorous megafauna, species that weighed over 45 Kg (100 pounds). Amongst the megafauna were mammoths, elephant relatives known as gomphotheres, horses, cow-sized animals known as Toxodon, and giant ground sloths. Sloths in particular seem to be connected to avocados, as they shared the environments of South America for far longer than the other megafauna.
The seeds of avocados would have been insignificant to the megafauna, allowing them to enjoy the nutritious fruit whole. Following their consumption, the seeds were transported great distances alongside the megafauna, eventually excreted in new locations across the Americas. Avocados weren’t alone in this adaptation, as plants like the Osage Orange also benefited from the presence of megafauna to transport their seeds. For a few million years, this symbiotic relationship between avocado and megafauna flourished, as both reached evolutionary peaks during the Pleistocene epoch. Just when all was going well, the megafauna disappeared.
To this day, paleontologists are still unsure about what truly caused the extinction at the end of the Pleistocene epoch, some 13,000 years ago. Regardless of the cause, the fact is that the majority of megafauna across the planet suddenly went extinct. Following this ecological collapse, it seemed as though the avocado would be doomed without its superspreading companions. Yet, as many health food buffs can attest to, avocados are still around today. How did they manage?
First, avocado trees have an exceptionally long lifespan. The average tree can live for anywhere between 200 and 400 years, making the species able to withstand a lack of seed distribution far better than other plants. Next, smaller animals like squirrels may have planted avocado seeds in the absence of megafauna, keeping enough new avocado trees in circulation for the species to survive. Lastly, another animal took over the role of avocado consumption and distribution: humans. The first evidence of avocado consumption by humans’ dates to around 10,000 years ago in caves inhabited by ancient peoples. Taking this into account, avocados would have only had to survive for ten generations or so before a new animal took over. A difficult task no doubt, but not impossible.
Even though mankind has embraced the avocado in our craziest health food trends, we haven’t succeeded in replicating the megafauna’s impact. While avocado plantations have emerged across the globe, wild species have dwindled over the last 10,000 years. Of the five species of wild avocado, three are at high danger of becoming extinct in the near future. While we turned avocados into a luxurious and tasty prize, we will never be able to replicate their special relationship with the megafauna of the Pleistocene.
References:
I do not take credit for any images found in this article.
Avocado preparation courtesy of Oleksandr Hrytsiv/Getty Images, found here
Cenozoic megafauna courtesy of Peter Schouten, whose work can be found at his website here
Sloth eating avocado courtesy of Adam Clarbon, found here
Greenfield, Patrick. “Avocados and Vanilla among Dozens of Wild Crop Relatives Facing Extinction.” The Guardian, Guardian News and Media, 7 Sept. 2021, http://www.theguardian.com/environment/2021/sep/07/avocado-and-vanilla-among-hundreds-of-crop-wild-relatives-facing-extinction-study-aoe.
Landon, Amanda J., “Domestication and Significance of Persea americana, the Avocado, in Mesoamerica” (2009). Nebraska Anthropologist. 47.
Pallardy, Richard. “The Curious Case of the Osage Orange and the Megafauna Extinction.” Earth.com, 18 Sept. 2018, http://www.earth.com/news/osage-orange-megafauna-extinction/.
Rupp, Rebecca. “How Hungry Humans Saved the Avocado.” Culture, National Geographic, 3 May 2021, http://www.nationalgeographic.com/culture/article/avocado-guacamole.
Smith, Annabelle. “Why the Avocado Should Have Gone the Way of the Dodo.” Smithsonian.com, Smithsonian Institution, 24 Oct. 2013, http://www.smithsonianmag.com/arts-culture/why-the-avocado-should-have-gone-the-way-of-the-dodo-4976527/.
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