Kale, Cauliflower, and Brussels Sprouts Are the Same Species

[ intro ] One of the most extraordinary things about
dogs is how different they all are. Like, we took one wolfy species and made over
200 breeds from adorable wrinkly pugs to lanky, powerful
greyhounds. And we didn’t just do this kind of whole-body-tinkering
with dogs. We’ve done it with plants, too. Just about all the fruits and veggies you
can buy at the supermarket have been shaped by human breeding. Most look totally different than their wild
ancestors. But there’s one plant species that’s produced so many different varieties that it’s known
to biologists as ‘the dog of the plant world’. You probably know it as kale. And broccoli. And cabbage. And brussels sprouts. T hat’s right, those are all the same species
of plant. Foodie favorites like kale and cauliflower are just a couple of the cultivars, or human-modified and grown varieties, of
Brassica oleracea. There are dozens more, from the logarithmic spiral of romanesco broccoli
to the distinct, pointed shape of caraflex cabbage. And you might think tons of variety is just what happens when humans selectively breed
something for generations. But that’s not entirely true. After all, we’ve been growing and breeding
lettuce for about the same amount of time, and yet, all lettuce varieties look pretty
lettuce-y. It turns out that B. oleracea is kind of a
special plant. It was so transformable because it underwent
some massive genomic event during its evolution. The story of why we have such a variety of
this kind of plant starts millions of years ago. Back then, an ancient Brassica ancestor did
something quite remarkable— it tripled its genome. That massive genome was whittled back down
to a more reasonable size by the time wild cabbage emerged as its own species about four million years
ago. Still, it meant that wild cabbage ended up
with a lot more genetic variation than your average garden plant. You see, broccoli and kale and brussels sprouts
don’t just look different. They’re very genetically distinct, too. And we’re not just talking little tweaks
to genes. In a 2016 paper, researchers sequenced the genomes of 9 different cultivars to construct
the plant’s pangenome— the total genetic variation that exists in
the species. And they found nearly 20% of the genes in
that pangenome are only present in some varieties. So not only do cultivars have a lot of mutational
differences, they also have whole genes that aren’t present
in other members of their own species, even though they all came from the same wild
cabbage. That plant, as far as we can tell, originated in the coastal areas of southern
and western Europe. We don’t know exactly when our species first
grew and domesticated it, but genetic evidence suggests it may have
been around 2000 B.C.E. The earliest written records come from ancient
greece, and they suggest the first cultivars were
leafy— veggies like kale and collard greens. And the Greeks weren’t the only ancient
people who tinkered with wild cabbage. Scientists are pretty sure that the plant
was domesticated many times in several locations. Some of these domesticated varieties found
their way back into the wild, became feral, and then were re-domesticated, adding even more to the species’ genetic
diversity. And all that genetic diversity eventually
allowed people to magnify different structural parts of the
plant. The variety we now call cabbage, for example, seems to have arisen sometime before the tenth
century when people bred a kale-like plant to have
larger buds on the tips of its stems. Brussels sprouts are also enlarged buds— the buds that grow all around the length of
the stem. And scientists aren’t quite sure when the
cultivar first emerged, but it was definitely being grown in Belgium
by the end of the 18th century. Then there’s kohlrabi, which literally means
cabbage turnip in German— presumably referring to its bulb-like enlargement
at the base of the stem. It’s not clear when it first came about,
either, but historical literature suggests it was
grown throughout Europe by the 1500s. Then there’s broccoli and cauliflower. Both get their unique florets—the yummy
parts we eat— from mutations to flowering genes. In broccoli, those mutations lead to a lot
of flower buds packed tightly together. Cauliflower has a lot of tightly packed flowering
structures, too, but most of them never actually flower. Instead, the white, pre-bud flower tissue
replicates itself as it grows, leading to the familiar, curd-like head. Since both have modified flowers, it’s thought that one came from the other,
but it’s still not totally clear which came first. As of 2018, genetic research seemed to be
leaning toward team broccoli. In fact, scientists are still trying to piece
together how we got all of these amazingly different
versions of Brassica oleracea and in what order. Trouble is, the same genomic shuffling events
which gave this species so much genetic diversity also make it challenging to figure out a precise
timeline for these cultivars and their relationships to each other. Researchers are eager to figure out as much
of that as they can, because it will also help them better understand
how the different varieties tolerate different environments, resist different diseases, and produce different
nutrients. You see, by better understanding these nutritious,
delicious, and fascinating dogs of the plant world, scientists just might figure out how to make
our favorite crops more hardy, sustainable, and nutritious. If you think these flexible plants are incredible, I bet you’ll like our episode on eight plants
that have mastered the art of deceit. And we’ve got so much more mind-blowing
science to tell you about! We put out a new video here on SciShow every day. And if you click that subscribe button and
ring the notification bell, you won’t miss a single one. [ outro ]

100 thoughts on “Kale, Cauliflower, and Brussels Sprouts Are the Same Species”

  1. (in the style of the Wicked Witch of the West's castle guard): BRASSICA…OLER-AAA-CEA! (c'mon, I can't be the only one…) 😉

  2. So much diversity, at what point is it a different species? Is there some core set of genes that links them all together?

  3. Can you guys do a video about dairy products and people that are allergic or lactose. I can eat a full tub of yogurt with zero problems I don't even get gassy at all. Then others in my family can only consume a little and then other in my family are lactose.

  4. @SciShow
    Could do a video explaining the difference between hybridization and genetic modification? A lot of people incorrectly use those terms interchangeably.

  5. Brasica is genetically fascinating. A close second is Citrus. There are only four species of citrus that all cross-breed with each other in the wild. (Which means it's really one species?)

  6. Why we never domesticated acorns is an interesting topic. Might make a good video. Not that I'm suggesting anything of course. Okay just shut up and make the damn video.

  7. the entire Brassica genus is an even more incredibly varied array of our aboveground vegetable consumption… with napus, rapa, juncea, and oleracea being the 4 that makes up our dipping mustard, canola/rapeseed oil, several turnips, pickled vegs, a huge portion of our leafy greens that aren't spinach and beets(both amaranths) or watercress(a nasturtium, cousins of brassica). if you've eaten chinese/japanese/korean, it's highly likely you've eaten various kinds of brassica and amaranth, especially of the leafy or …stemmy(?) varieties(like gailan or kohlrabi or the pickled zhacai). my favourite are 2 juncea, the somewhat bitter Chinese mustard green(head mustard) and mizuna(long thin stemmed leafy green for shabu shabu), and a rapa called tatsoi (grown and matured under snow and very sweet)

  8. So, species means you can still get viable offspring between all the cultivars – even the most extreme ones with 20% genetic difference? How does that even work?

    If so how does that offspring look like – and how does it taste?

  9. OMG! Having graduated with a botanist degree, I had a chance to work with brassica in the tissue culture lab in college. I'm a programmer now, bu being a home Gardener for the last 20 years, I've been telling my friends about this fact all my life! Is one of my favorite tidbits to share with other gardeners.

  10. True. I see the varietie's missing link in my garden by volunteers. Very hardy specie and works well here in a damp jungle.

  11. At 2:01 I think maybe I don't understand what species means, surely if they are very genetically different hey are of different species? I thought each breed of dog was a different species too.

  12. LOLWTF First evolutionists tell you you come from monkeys now they claim plants evolve like dogs. Can't get much more silly. And this is tought in schools?? THAT is a crime!
    What happened to a species being able to reproduce? LOL I've never seen a broccoli and cauliflower make brocciflower babies.

  13. 3:49 im german and turnips are called rübe
    the rabi thing must be some ancient dialect or sth never heard of it

  14. Can somebody explain to me simply what exactly do we mean by species? If their genetic makeup is so different how do we know they are the same species?

  15. Stupid question I’m sure but: if the genetic sequences of each variety are so drastically different why are they not separate species with the brassica being the parent?

  16. i still don’t get how literally half of the root and vegetables are from the nightshade family, like how are tomatoes, potatoes, peppers, tobacco and eggplants all in the same family

  17. I'm surprised this episode doesn't address the most obvious (IMHO) question. If these cultivars are so generically different, why aren't they considered different species?

  18. If there’s 20% genetic difference between these different cultivars, then why aren’t they considered different species?

  19. I was low-key fascinated with cabbage relatives since I was a small child. My mom used to tell me a lot about plants, including those we grew in our vegetable garden, I learned a lot and I enjoyed learning it all.

  20. In the German language it is made clear by their names that they are the same group of plants. They are named "green cabbage" (kale), "flower cabbage" (cauliflower) and "rose cabbage" (sprouts). So no news for me. ^^

  21. Wait, so you don't have Kohlrabi in america?
    They taste delicious when the plant is still young and they are freshly harvested.

  22. As a Horticulturalist this is one of my favorite facts to tell a someone when asked "what kinds of things do you learn?"

  23. "Your Honor, I offer as proof of my complete unfitness to serve on Jury Duty the fact that I watched a YouTube video about the history and evolution of cabbage, broccoli, cauliflower and kale."

  24. Might be worth touching on what makes it a "species" as opposed to a genus or a family: two lifeforms are said to belong to the same species if they can be bred together and produce fertile offspring. For an illustrative non-example, if you breed a horse with a donkey, you get a sterile mule; the only way to make more mules is to continue breeding horses with donkeys, thus horses and donkeys are at a bare minimum different species. By contrast, any cultivar of brassica oleracia can breed with any other cultivar to produce a fertile hybrid. Get enough of those hybrids together and you can start your own self-sustaining cultivar. That's how we got broccoflower.

  25. This species also includes Asian greens like chinese cabbage, choy sum, bok choy, gai lan (aka Chinese broccoli) and Chinese mustard. Other plants include rutabaga, turnip and some seeds used in the production of canola oil and mustard.

  26. Cauliflower, I can use it as rice, cous cous and mashed potato substitutes. Very versatile and very edible. Cabbage, Kale and Broccoli all produce a high fodmap reaction that's tough on my gut. Although I can use them as ingredients in recipes in small amounts. Brussels sprouts are only eaten once a year at Christmas dinner so I don't worry about them too much. I do like a bit of sauerkraut though. In fact all breeds are great for fermenting.

  27. >start gardening, decide to grow broccoli
    >Broccoli gets destroyed by little green worms
    >Find out about cabbage moths
    >Try cabbage next year
    >More cabbage moths, end up with a pitiful yield.
    >Realize I'm dumb and they're lowkey the same species.

  28. Wild cabbage has been around peacefully since 4 million years…..
    Guess not that dumb after all…..,humans: 'take notice' !

  29. my question is really this: who looked at some of these foods and said, hey ill bet we could eat that if we made "this specific part of it" bigger.

    i mean, the wild version of almost everything we eat, is nigh inedible.

  30. Yay! Another video about Agriculture! These are my favorites… but that might be because I'm actively studying this stuff…

  31. This isn’t a first time I hear about variety of cabbage.
    But now I think, why we even consider all cabbages as only 1 specie?

  32. Outstanding video– it's such a tricky question and you did an outstanding job summarizing what we know so far! (thanks for the citation as well!)

  33. So basically you are saying all the shitty, bitter, plants that no one in their right mind would eat are the same species of shitty, bitter, plants that no one in their right mind would ever eat. That they were cultivated shows just how desperate survival was in ancient times.

  34. So are there any "original" specimens if Brassica Oleracea? And has anybody tried cross-breeding the different cultivars to see what they get?

  35. Do they all have the same number of chromosomes. Can we just breed them together. Make cauliflower Brussels sprouts

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