Ah summer…the perfect time for a delicious guacamole quesadilla or a tasty avocado salad. But have you ever looked inside an avocado? Beneath the delicious green flesh is an immense hard seed as big as a golf ball. Trees compete by spreading seeds efficiently. The Norway maple in my back yard produces thousands of helicopter seeds which fly off in every direction on their own rotors. The black cherry entices countless birds to eat its fruit, pit and all, and thereby spread its seeds afar on feathered wings. What purpose does the avocado’s giant seed serve?
Gomphotheres--can you imagine these guys running around Texas?
Well, avocado trees as a species are ancient. They evolved together with giant mammals like glyptodons, gomphotheres, and giant sloths. These immense herbivores could eat avocados whole and not even notice the seeds. The animals would forage away from the original tree and, in the course of time, leave the seed in a totally different location along with a pile of fertilizer. Osage oranges are similarly symbiotic with the giant extinct grazers. In the absence of these creatures, wild avocados and Osage oranges are slowly losing ground to other trees–even if human kind has planted the avocado for food and the Osage orange for its springy wood (which is perfect for archery).
Giant Sloth
So what happened to all these wonderful beasties? Why is a nature documentary shot on the grasslands of Africa today so much more satisfying then one from the great Texas Llano? Alas, they went extinct 12000 to 14000 years ago—just about the same time humankind showed up. It turns out the first humans to get to the New World loved killing charismatic megafauna even more than Buffalo Bill did.
ferrebeekeeper 
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August 6, 2010 at 3:15 PM
Rachel
It’s surprising that humans can eat avocados at all. Avocado (esp the skin) is toxic to dogs, goats, cattle, horses, rabbits and rats.
August 10, 2010 at 4:52 PM
Hieronymo
Osage Oranges actually are mildly toxic to us–they cause vomiting. Most contemporary North American animals also find them inedible–though not apparently perissodactyls (which are increasingly believed to be the intended seed dispersers). I still wouldn’t feed one to an endangered rhino.
August 9, 2010 at 1:03 PM
Alana
Fascinating! And to Rachel’s point, I was so surprised to find out that avocado is toxic to dogs (an alert friend gave me and Aron a list of toxic foods when we got Moxie).
“Charismatic megafauna” is an extremely apt phrase for that giant sloth, who looks like he or she is making sweet, sweet love to that (avocado?) tree.
August 10, 2010 at 4:44 PM
Hieronymo
I think the gomphotheres and the glyptodon are pretty charismatic too! The former look like they are singing a humorous song and the latter seems to be seeking his missing copy of the Financial Times. I have used “gomphothere” as my dump email pseudonym for years because I like to imagine one of the giant beasts gobbling up the spam, junk mail, and sundry garbage while aggressively stomping on the senders.