Chopped in a salad or mashed on toast, how do you like your avocado? Or maybe you don’t like them at all, they seem to divide the masses and while they are certainly no potato, by Irish standards, the fact that they have survived this long and are now found on Irish plates is no mean feat. Especially considering their original consumers are extinct. So how did the avocado survive?
At first glance avocados and potatoes have very little in common. For starters, one is a fruit and the other a vegetable. However, when we delve a little deeper we realise that both are a good source of vitamins, minerals and fibre and both would have been enjoyed by prehistoric farmers, the Aztecs.
Plants produce fruit for one main reason, endozoochory, seed dispersal by means of ingestion by an animal. The advantage to this method is that those animals will then usually transport those seeds a considerable distance away from the parent plant, before depositing them. So the new plant has a chance to survive without having to compete with the parent plant for light, water and nutrients.
The avocado used endozoochory as its means of seed distribution too. It created one very big seed in one very big fruit so, naturally enough, it needed to attract some very big animals. This wasn’t much of a problem back in the early Cenozoic Era when megafauna abounded. Large animals like the giant ground sloth (as tall as modern giraffes) and glyptodons (huge armadillo-like animals as big as a modern car) were happy to snack on the tasty fruit.
The seeds contained a mild toxin, called persin, which is thought to make it too bitter to tempt these giants to eat, but they were large enough to swallow it whole. They were also big enough to travel large distances from the parent plant before the seed eventually travelled through their digestive system and was released in a ready-made pile of manure.
It was a perfect set up for both plant and animal. Unfortunately, it didn’t last. The avocado hit an evolutionary blip with the extinction of their large gutted grazers some 10,000 to 13,000 years ago.
So why is guacamole even a food choice today? Surely the fruit should have died off with its evolutionary partners? It seems it almost did. The avocado joined the list of other anachronistic fruits, like papayas and prickly pears, that somehow hung on despite the evolutionary disadvantage, making it all the way to the current day.
It would appear that humans became the unusual ally that the avocado needed, developing a taste for their buttery flesh. For once we may have had a positive role to play in the survival of the species. Of course, we may also have had a role to play in the eradication of the megafauna that assisted them in the first place, so it’s certainly not the time for celebration.
Avocados appear to be unsavoury (and possibly toxic) to most modern animals so humans may really have saved the plant, evolving to a point where we could cultivate the seeds. With time we were able to select for plants that produced fruit with more flesh, as we have today.
The Aztecs really put the avocado on the menu and today there are more than one billion kilograms of the fruit consumed annually, in America alone. That’s a pretty impressive come-back.