whether it’s sliced on top of a salad, tuckedin a california sushi roll, or mashed as guacamole in a burrito, people seem to love avocados. in fact, people in the united states munchedthrough four billion of them in 2014 alone. they taste great, they’re good for you -- butone of the most amazing things about avocados is that ... they still exist.
crash diets pdf, see, they had a special relationship withhuge beasts that lumbered around central america tens of thousands of years ago. and when these animals went extinct, avocadoscould easily have gone down with them. but, luckily for us, they were saved by someprehistoric farmers.
the word ‘avocado’ comes from the aztecs.specifically, the nahuatl word ahuacatl, which means ... testicle. i mean, you can kind of see where they gotthe name -- it probably has something to do with the, uh, you know the shape and textureof avocados, the way they hang from trees. anyway, before they became popular in therest of the world, they were cultivated in mesoamerica for thousands of years. avocados are a fruit – basically, swollenplant ovaries. but, nutritionally, they’re very differentfrom other fruits you’d find at the supermarket. fruits like apples and oranges are composedmostly of water and sugar.
and in general, fruit is probably better foryou than, say, a bag of sweets or a sugary drink because it contains fiber, which slowsdown sugar absorption and makes you feel fuller, faster. by comparison, avocados have much less sugarbut more protein and fat. that gives them that smooth, creamy texture, but also putsthem on the calorific side – for a fruit, anyway. they also contain high levels of potassiumand folate nutrients, as well as vitamins c, e and k. and technically, avocados are berries, likegrapes and blueberries.
rather than holding lots of little seeds,the avocado goes all-in on one big seed – that massive ball at the core of each fruit. and avocadoes, with their huge seeds, evolvedalongside equally huge guts. tens of thousands of years ago, during thepleistocene epoch, a menagerie of megafauna -- or, giant animals -- roamed the americas. while woolly mammoths chilled out in the north,ground sloths weighing three tons and armadillos the size of cars lived in the warm equatorialforests. and these giant sloths and armadillos atea lot of avocados. their digestive systems would break down thetough skin and absorb the high-energy pulp.
then, the indigestible seed, which containsbitter toxins that kept the animals from chewing it up, passed right out the other end. the animals got a tasty meal, and the avocadotrees got to scatter their offspring throughout mesoamerican forests. plus, the seeds got some nice, warm fertilizerto give them a nutritious boost. and with these megafauna around to eat thefruit, avocado trees could keep growing berries with increasingly massive seeds. the bigger the seed, the more nutrients couldbe stored inside as a “starter kit†for the baby tree.
this is especially useful in dense, tropicalforests where canopies of older trees block out much of the light from the saplings below. so instead of depending entirely on sunlightfor energy, the avocado seedlings could supplement photosynthesis with the nutrients in theirseed to survive. this happy evolutionary match didn’t last,though. eventually, the megafauna suffered a mass extinction around ten to thirteen thousandyears ago. we don’t know exactly why, but scientiststhink the warming climate at the end of the last ice age was partly responsible. though it was also suspiciously close to thetime humans began spreading across the americas
-- no doubt enjoying lots of giant-mammalmeat along the way! this meant avocados were in trouble. without their large-gutted evolutionary partners,the trees stopped thriving -- their fruit fell to the ground, and the seeds mostly justbecame food for mold. but more hungry creatures were nearby! the new human arrivals loved the avocado’sflesh as much as the ground sloths did. they also had the tools to eat them, and the brainsto figure out how to grow them. avocados were all set for domestication. the avocados we eat today are probably a littledifferent from the ones that grew tens of
thousands of years ago -- for example, thanksto artificial selection, they probably have more pulp than their ancestors. but they’ve kept their huge seeds, readyand waiting for the guts of long-dead beasts. thanks for watching this episode of scishow,brought to you by our patrons on patreon. if you want to help support this show, justgo to patreon.com/scishow. and don’t forget to go to youtube.com/scishow and subscribe!
0 komentar