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Love avocados? Thank the toxodon
Avocado evolved in the warming climates of Central America during the Neogene period, roughly 10 million years ago.
Given avocado's popularity today, it's hard to believe that we came close to not having them in our supermarkets at all.
In my new book “Avocado: A Global History," I explain how the avocado survived a series of ecological and cultural close calls that could have easily relegated them to extinction or niche delicacy. Instead, the avocado persevered, prospered – and became one of the most Instagrammed foods in the world.
A 'ghost of evolution'
Avocados are in the laurel family, the same group of plants that includes bay leaves and cinnamon. Laurel trees prosper in warm subtropical climates, and the avocado evolved in the warming climates of Central America during the Neogene period, roughly 10 million years ago.
During the Pleistocene era, which followed the Neogene, the biggest animals on Earth were what we call the megaherbivores – giant animals that subsisted almost entirely on a vegetarian diet. Most of these, like the giant ground sloth, would have dwarfed today's largest megaherbivore, the African elephant. The giant herbivores of Pleistocene Mesoamerica like the gomphothere, the giant armadillo and the toxodon needed hundreds of pounds of food a day just to survive. Since food like leaves and grasses are so low in calories and fat, the animals prized any energy dense and fatty foods.
Enter: the avocado.
Megaherbivores didn't peel the avocados and eat the green meat like we do today. Instead, their throats and digestive tracts were so large that they would simply swallow the avocado whole and excrete the undigested pit. In a process known as endozoochory, the pile of manure would serve as food for the next generation of avocado trees. As these giant animals roamed and grazed on avocados, they spread the fruit across what is now central Mexico.
Megaherbivores like the toxodon were the avocado's best friend. (Robert Bruce Horsfall/Wikimedia Commons)
But once the megaherbivores died off, the fruit was in a bind. The herbivores that were left had throats far too small to ingest a whole avocado seed, and dropping a giant seed at your own roots is a poor survival strategy for a tree; to thrive, it needs to disperse more broadly.
Avocados became what the botanist Connie Barlow calls a "Ghost of Evolution" – a species that should have gone extinct but was somehow able to survive. What the avocado had going for it was the lifespan of its trees, which survive much longer than most fruit trees. There are 100-year-old trees still producing fruit in California and 400-year-old trees in central Mexico.
By living so long and being so well adapted to their ecological niche, avocados were able to hold on until their next dispersers – Homo sapiens – came along.
More stops and starts
The earliest humans in Mesoamerica were quick to appreciate the virtues of the avocado. Groups like the Olmecs and the Maya started the first avocado orchards and began cultivating specimens that tasted the best and had the meatiest fruits, a process of trait selection that gave us the kinds of avocados we love today. Avocados were so important to the Maya that the 14th month of their calendar was named for them.
In the 1830s, Floridian Dr. Henry Perrine was introduced to avocados while serving as U.S. consul in Campeche, Mexico, and thought they would be an excellent addition to Florida's horticultural offerings.
He sent some seeds to a friend on Indian Key in Florida who planted them. Not long after Perrine returned, the Second Seminole War broke out. Perrine and his family sought shelter from the fighting on the key, but he was killed during a raid on the island by one of the warring factions. The island was abandoned and the avocado trees were forgotten.
Hot and humid Florida had been hospitable to the avocado, but California has enough cold snaps in the winter months to make it difficult for most avocado varieties to thrive there. This could have been another dead end for the fruit, but early settlers in California took another stab at establishing them in the U.S. After a few failed attempts in the 1850s and 1860s, grower Judge R. B. Ord obtained a few cold-hardy specimens from central Mexico. A cold-tolerant variety was needed if California was to have a profitable avocado industry. Without it, the avocado might have remained a delicacy local to Mexico and its neighbors.
One of the earliest cold-hardy specimens was a variety given the name "Fuerte," which means "strong" in Spanish. The Fuerte avocado earned its name because it was one of the few varieties that survived the famous "Freeze of '13," a spell of cold weather that nearly ruined the nascent fruit industries of Southern California in the winter of 1913.
Until the 1940s, the Fuerte was the most popular avocado variety in America and made up about 75% of avocados sold.
The Hass comes to pass
The Fuerte has since been relegated to niche product, and represent only about 2% of the California market. Instead, the lion's share of avocados sold today are the variety known as Hass, which rhymes with "pass."
But were it not for a couple of kids with precocious palates, the world may never have tasted a Hass avocado, with the fruit remaining an odd delicacy for the well-to-do.
The Hass avocado is named for Rudolph Hass, a mailman who lived in La Habra, California. Originally from Milwaukee, Hass joined the thousands of Americans who went west to California in the 1920s and 1930s.
After reading a brochure about the money to be made in avocado ranching, he borrowed enough money to buy a small plot of land with Fuerte avocado trees on it. In the late 1920s, Hass bought some avocado seeds to grow rootstock for his budding nursery. One of these seeds grew a funny tree that rejected the Fuerte limbs that Hass wanted to graft onto it – a process that involves combining two tree plants with distinct characteristics. He was about to cut the misbehaving tree out, but his kids told him that these odd little avocados were their favorites, so he relented and kept the tree. After trying them himself, he thought they had marketing potential and began selling them to people at work and at a market in town.
Hass avocados slowly caught on, and in 1935 Hass patented the tree, the first patent awarded for a tree in America. But most growers, instead of buying his tree, evaded his patent and simply grafted their cuttings themselves. This practice was illegal, but enforcement in the 1930s was spotty.
Today, Americans eat 100 million pounds of avocados on Super Bowl Sunday, and Hass should have died a rich man. But he never earned enough to quit the post office, and it's estimated that he only made about US$5,000 on the patent in his lifetime.
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A new study finds that dogs fed fresh human-grade food don't need to eat—or do their business—as much.
- Most dogs eat a diet that's primarily kibble.
- When fed a fresh-food diet, however, they don't need to consume as much.
- Dogs on fresh-food diets have healthier gut biomes.
Four diets were tested<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NjY0NjIxMn0._w0k-qFOC86AqmtPHJBK_i-9F5oVyVYsYtUrdvfUxWQ/img.jpg?width=980" id="1b1e4" class="rm-shortcode" data-rm-shortcode-id="87937436a81c700a8ab3b1d763354843" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: AntonioDiaz/Adobe Stock<p>The researchers tested refrigerated and fresh human-grade foods against kibble, the food most dogs live on. The <a href="https://frontierpets.com.au/blogs/news/how-kibble-or-dry-dog-food-is-made" target="_blank">ingredients</a> of kibble are mashed into a dough and then extruded, forced through a die of some kind into the desired shape — think a <a href="https://en.wikipedia.org/wiki/Food_extrusion" target="_blank">pasta maker</a>. The resulting pellets are sprayed with additional flavor and color.</p><p>For four weeks, researchers fed 12 beagles one of four diets:</p><ol><li>a extruded diet — Blue Buffalo Chicken and Brown Rice Recipe</li><li>a fresh refrigerated diet — Freshpet Roasted Meals Tender Chicken Recipe</li><li>a fresh diet — JustFoodforDogs Beef & Russet Potato Recipe</li><li>another fresh diet — JustFoodforDogs Chicken & White Rice Recipe.</li></ol><p>The two fresh diets contained minimally processed beef, chicken, broccoli, rice, carrots, and various food chunks in a canine casserole of sorts. </p><p>(One can't help but think how hard it would be to get finicky cats to test new diets. As if.)</p><p>Senior author <a href="https://ansc.illinois.edu/directory/ksswanso" target="_blank" rel="noopener noreferrer">Kelly S. Swanson</a> of U of I's Department of Animal Sciences and the Division of Nutritional Sciences, was a bit surprised at how much better dogs did on people food than even refrigerated dog chow. "Based on past research we've conducted I'm not surprised with the results when feeding human-grade compared to an extruded dry diet," he <a href="https://aces.illinois.edu/news/feed-fido-fresh-human-grade-dog-food-scoop-less-poop" target="_blank">says</a>, adding, "However, I did not expect to see how well the human-grade fresh food performed, even compared to a fresh commercial processed brand."</p>
Tracking the effect of each diet<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3NjY1NTgyOX0.AdyMb8OEcjCD6iWYnXjToDmcnjfTSn-0-dfG96SIpUA/img.jpg?width=980" id="da892" class="rm-shortcode" data-rm-shortcode-id="880d952420679aeccd1eaf32b5339810" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: Patryk Kosmider/Adobe Stock<p>The researchers tracked the dogs' weights and analyzed the microbiota in their fecal matter.</p><p>It turned out that the dogs on kibble had to eat more to maintain their body weight. This resulted in their producing 1.5 to 2.9 times the amount of poop produced by dogs on the fresh diets.</p><p>Says Swanson, "This is consistent with a 2019 National Institute of Health study in humans that found people eating a fresh whole food diet consumed on average 500 less calories per day, and reported being more satisfied, than people eating a more processed diet."</p><p>Maybe even more interesting was the effect of fresh food on the gut biome. Though there remains much we don't yet know about microbiota, it was nonetheless the case that the microbial communities found in fresh-food poo was different.</p><p>"Because a healthy gut means a healthy mutt," says Swanson, "fecal microbial and metabolite profiles are important readouts of diet assessment. As we have shown in <a href="https://academic.oup.com/jas/article/92/9/3781/4702209#110855647" target="_blank">previous studies</a>, the fecal microbial communities of healthy dogs fed fresh diets were different than those fed kibble. These unique microbial profiles were likely due to differences in diet processing, ingredient source, and the concentration and type of dietary fibers, proteins, and fats that are known to influence what is digested by the dog and what reaches the colon for fermentation."</p>
How did kibble take over canine diets?<p>Historically, dogs ate scraps left over by humans. It has only been <a href="https://www.thefarmersdog.com/digest/the-history-of-commercial-pet-food-a-great-american-marketing-story/" target="_blank">since 1870</a>, with the arrival of the luxe Spratt's Meat Fibrine Dog Cakes—made from "the dried unsalted gelatinous parts of Prairie Beef", mmm—that commercial dog food began to take hold. Dog bone-shaped biscuits first appeared in 1907. Ken-L Ration dates from 1922. Kibble was first extruded in 1956. Pet food had become a great way to turn <a href="https://www.dogfoodadvisor.com/choosing-dog-food/animal-by-products/" target="_blank">human-food waste</a> into profit.</p><p>Commercial dog food became the norm for most household canines only after a massive marketing campaign led by a group of dog-food industry lobbyists called the Pet Food Institute in 1964. Over time, for most households, dog food was what dogs ate — what else? Human food? These days more than half of U.S. dogs are <a href="https://www.nytimes.com/2014/08/03/magazine/who-made-that-dog-biscuit.html" target="_blank">overweight or obese</a>, and certainly their diet is a factor.<span></span></p><p>We're not so special among animals after all. If something's healthy for us to eat—we're <em>not</em> looking at you, chocolate—maybe we should remember to share with our canine compatriots. Not from the table, though.</p>
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Eating veggies is good for you. Now we can stop debating how much we should eat.
- A massive new study confirms that five servings of fruit and veggies a day can lower the risk of death.
- The maximum benefit is found at two servings of fruit and three of veggies—anything more offers no extra benefit according to the researchers.
- Not all fruits and veggies are equal. Leafy greens are better for you than starchy corn and potatoes.