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In which John discusses the strangely hopeful history (and future?) of avocado trees and their extraordinary fruit. It's a tale of coevolving with mammals that no longer exist, and yet finding a way to go on.

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Good morning, Hank, it's Tuesday.
You want to know something wild about avocados? You know how, when you open up and avocado, there's a toy inside, just like a Kinder Egg except it's always the same toy; it's a wooden ball? Well that turns out to be a seed.

Now you'll note that the avocado seed is much, much larger than, say, and apple seed or a carrot seed or an acorn, which turns out to be because the avocado tree co-evolved with all this American mega-fauna, which by the way is a good name for a band.

Here we need a brief side note on the history of mammals in the Americas. So, until about about 12,000 years ago, there were all of these huge animals in the Americas. Like there was a beaver that weighed almost 300 pounds, there was the mastodon, the American lion, the dire wolf turns out not to have just been a thing from "Game of Thrones". There were also these giant armadillo-looking things called glyptotherium, that weighed up to 2000 pounds, and giant sloths that were 15 feet tall, and massive bears that may have had to eat, like, 35 pounds of meat per day to survive. And all of these animals, and many more, lived in the Americas for over a million years before they all went extinct, along with many other large mammal species about 12,000 years ago, at the end of the Pleistocene Epoch. Why did they go extinct? That is a much debated question and I am not looking to get into any fights with Paleobiologists.

Some argue that Climate Change was the primary factor, some argue that human behavior, including over-hunting may have contributed to the extinctions, but at any rate, back in those days, you saw a lot more seeds the size of avocado seeds. 

And this makes sense, right? Because it was not a big deal for a glyptotherium or a giant sloth to eat an avocado and poop out the seed because they were huge animals with correspondingly huge poop holes. This was great for everyone involved, because the animal would get some fats and vitamins from the avocado and then walk for a while before pooping, which would allow the avocado to spread, and give it a bit of fertilizer to start its life with.

But then like 12,000 years ago, this seed dispersal strategy went away with the extinction of all of these large animals and suddenly all the squirrels were like, "I mean, I'm not going to poop out that avocado."

So, many of these large-seeded trees declined or went extinct, with the major exception of the avocado. Why? Two reasons.

First, avocado trees live for a really long time; like, they can live for over 400 years, so they had a long runway to try to figure out how to live without giant mammals. But probably the biggest factor was humans. There's evidence that humans were consuming avocados 9 or 10 thousand years ago, but we may have been trading and cultivating them even before that. And so via humans, the avocado spread from its home in what is now Central Mexico to South America, and the Caribbean, and, eventually, the world.

I find it quite encouraging to consider that humans living all that time ago did us this huge, huge favor by preserving the avocado. But it's also a reminder that the choices we make as humans can reverberate thought history, not just for, like, dozens of years, but for tens of thousands. Because, like, strangest of all, contemporary humans have begun to try to make avocado pits smaller, so that we can have more avocado in our avocados. And if they succeed, it's possible that we could arrive at a time when avocado seeds are small enough that they could be pooped out by, say, a raccoon, meaning that, potentially, the avocado tree could survive the age of humans, just as it survived the Pleistocene. Not in spite of humans, but because of us.

We are not merely a force of destruction in this world, and we certainly don't have to be merely a force of destruction. And the avocado is a reminder or that.

Hank, I'll see you on Friday.