Thanks to everyone who pointed out the 'Acher Saccharum' typo! The video has now been annotated with the correct spelling. Also-- thank you for pointing out that berries were being represented by an impostor graphic: the strawberry. -Sarah (Editing and Graphics)

I really don't understand why people thumbs down stuff like this. I mean did the color of the leaves offend someone cause it doesn't show a specific hue or they're skin tone. Of course this is just a opinion based on what many people fret about in life. Themselves.

Let the trees pick up their own goddamn leaves.

It wasn't really in the video, but I love the image of the grim reaper holding a rake instead of a scythe.

This dude looks like he belongs in a final fantasy game wielding a massive sword

I liked the video, especially your having stated that the leaves don't *change* color so much as lose the green. But raking instead of composting is a bad idea. I wish more of us had the room to allow the leaves return to the soil.

Great stuff! Thanks, you guys!

I used to ask my father the same question every Autumn: "How did nature deal with fallen leaves before humans invented the rake?" I've never gotten a satisfactory explanation as to why it was necessary for me to spend hours raking and stuffing leaves into non-biodegradable plastic bags, just so the garbage man could haul them off and throw them into a landfill.

This is something I hear asked a lot, even in the comments here! Do trees and plants feel "pain" or "emotion"? Can you hurt a tree or any plant? Does ripping/picking off a leaf off of a bush or a tree "hurt" it? These are things we can all benefit from being more aware of. Please and thank you SciShow

I learned that at five years old. Glad you are sharing it here. I should have thought to do so.

Actually, the yellow pigments are there all along while the red ones are _produced_ in fall. There are different theories as to why that is, from protection against the sun while there is less chlorophyll in the leaves to sending a signal of health to plant-eating animals but whatever it is, red wasn't there to begin with.

as a lifelong resident of boston, massachusetts, i've become so incredibly jaded to the changing colors in fall because of all of the god damn new yorkers that come here to clog up our streets and stare at yellow trees

1:13, the label should read "Acer saccharum" when it reads "Acher saccharum." I do enjoy the videos (though this one was rather elementary in explanations), but I also hate misspellings in botanical nomenclature. Thanks Michael and the rest of the SciShow team for educating the formidable student that is the Internet!

I thought the colors were because the tree was blushing as it slowly becomes naked.

I can listen to this guy all day.

You gave a very "elementary" explanation to this phenomena and I was a bit disappointed. I just attended a tree phenology lecture the other day that discussed a couple hypotheses in literature explaining leaf senescence. The reason why this explanation is lacking is because trees senesce at varying times and intensity. Also, anthocyanins and carotenoids were found to be produced more at the time of senescence, contrary to the belief that these pigments are always within leaves throughout the year. This suggests that the reasons for senescence are a bit more complex than the simplest explanation. A couple theories are proposed in literature to explain this phenomenon in terms of the interactions of trees with predating species (such as aphids). W.D. Hamilton in 2001 suggests the Honest Signalling Hypothesis which says that the brilliant display of colour is to signal to insect pests that they are well defended and should not be attacked for the winter (read more here: doi: 10.1098/rspb.2001.1672). Other hypotheses include using these pigments to protect from light damage (10.1104/pp.103.027631) and the change in colour in response to the visual capacities of aphids (10.1016/j.tree.2008.10.006). These are all hypotheses that address the paradoxes which the "less light less chlorophyll" explanation fails to explain. I was a bit disappointed in that I expected SciShow to address the literature and show new perspectives on topics that might seem obvious to us.

Bless you for this, this is just in time for my science unit.

This is called senescence. The pigments don't just go away but the plant is recycling them by disintegrating them. en.wikipedia.org/wiki/Plant_senescence

I love the colored leaves in autumn! :D Playing in the leaves is one of my fondest memories from childhood.

Why aren't leaves green in the fall? Because Hank is.

I swear there is more to this as well. I remember reading a study that showed the leaves also have a chemical added to them that makes them hostile to anything on the ground. So as they rot, if anything tries to grow under that tree, it cannot because of the chemicals from the rotting leaves in the soil.

So this is the tree's way of clicking Windows > Shut Down > Hibernate.

I think Michael Aranda is awesome to look at.

The thumbnail led me to believe you had a new (rather agèd) hosted. Boy, was I glad to see Michael. :)

Dammit, it is autumn already. Time to change wallpaper on my desktop =)

Here's some more tree related questions. Why do conifer trees like pine trees have small spikey leaves? Why don't they lose their leaves in the winter, even when they are exposed to weeks of almost total darkness; and how do they manage photosynthesis in areas with such weak sunlight?

f**king love sci show ARRHRRRGGHGHHGHGHGHG

i like this video. great job

But it's also because snow and ice on leaves weighs a lot more when it's on leaves and the tree's limbs would break under the weight.

"nature taking extreme measures to conserve energy" would be a better entrance

AhA something to correct ! :D Anthocyanins may color both berries and strawberry, but a strawberry is not a berry :P

At around 00:42 correct me if I'm wrong; but isn't the number one job of a plant to reproduce, (as is the same for all other organisms.)?

I prefer to mulch the leaves and leave them on the ground. Put the nutrients back into the system...rather than buying more fertilizer at the store.

the fall has come unusually early here in southeastern new york state. the leaves started to change color & fall off before the season even started. I've never seen fall come this early. the winter was extremely cold & stormy; the spring was very rainy; the summer was unusually cool. & fall is here unusually early. I can't help but ask "WHY??"

The reality that the leaves don't change colour but actually just lose pigment sort of crushes my childhood fantasies about autumn faires....

You should do the science behind jello/gelatin, like how it turns from a powder to jello? what makes it hold its form?

Another reason for the falling of leaves is to avoid the problem of heavy snow, as we saw on Oct 29th 2011 in New England.

I have noticed from the trees in my garden (in Iceland) that they do not shed their leaves if the wind is blowing. That way, when the leaves fall, they do not blow away and the tree can use the rest of the nutrients for itself.

they change color when there rent is due (different shades represent different amounts of debt), they fall off when evicted. i thought everyone knew this?

thx u so much!😊😁

Where I live in Florida we only have two season, summer and not summer. Even if a tree drops it leaves it completely skips the fall color change, just goes straight from green leaves to barren.

Deciduous trees near a house block much of the sun's warming light in the Summer, but let's much of that warming light reach the house in the Winter (at least on sunny days), so it lowers energy costs.

I clicked on the video because I needed a reminder lol Thanks guys!

Hmmm coincidentally I was thinking about this the other day. My conclusions were pretty different so thanks for revealing the truth to me ^,^

Also snow will not pile up and snap branches like it did during the summer snow storm in Calgary when all the tree still had green leaves. The city is still recovering from all the down branches. www.flickr.com/photos/zakna/sets/72157647102466790/

Is it possible to strain your retinas if they have to close too fast because of sudden light exposure? Or open? What is in the light that makes them react?

I don't if Vsauce said this in a video but I heard that they change color because they try to resist against the dropping temperatures and the shorter days and so the trees that are probably the weakest lose their leaves as a green or yellow but much stronger trees tend to keep resisting and that's causes the leaves to turn to a darker orange then brown, I don't know which is right.

DUDE I WEAR THE EXACT SAME HOODIE AS YOU HAVE RIGHT NOW HOW COOL IS THAT :)))))) but its from h&m in germany? how is this even possible?

Leafs are falling to protect branches of a tree from the masses of snow, that could accumulate on the surface of the leaf

Somehow I got the impression that the guy in the picture used for the thumbnail would be explaining this one.

Living in LA i dont know what the hell fall/Autumn is.

You guys should get clothing sponsors and provide links to clothing that you are wearing in each episode.

@UnashamedlyHentai Yes, and if you listen closely, you can hear the tree quietly say "ouch."

This is not quite the whole story! It's been demonstrated that trees actually synthesise some of the pigments, they were not there before. This is likely a message to pests: the healthier the tree, the more striking the colour, the worse a place it is for parasites to overwinter, since healthier trees will mount stronger defences and more quickly in spring. Just like gazelles jump to show off their strength when they spot a predator. Cleverer than you thought!

SciShow I want to see MIchael host more videos!

His earlobes jiggle when he moves his head. It's quite distracting, yet very hypnotizing.

Hey Its nice video but need little changes, in the end you said all the pigments are already there but its not totally true, I work with betalain (another pigment similar to anthocyanin), there are researches which suggests that plant synthesise these pigments when they need it (i.e anthocyanin or betalain under various stresses). These are not always there.

Just a heads up: the maple genus is acer not acher, as shown in the picture.

01:47 How can anyone look badass holding a rake...?

Is that guy with the rake trying to recreate Grant Wood's "American Gothic"? Because if he is, kudos for the facial expression.

''Deciduous' from the Latin "To fall".' Don't know why, but I found that sentence very funny.

You missed out on an opportunity to mention the Deciduous Beech, the only Australian native plant to lose its leaves in response to the cold.

So what happens if you plant a northern or southern deciduous tree species near the equator where the temperature and quantity of sunlight doesn't vary much year-round? Would the tree just stay green all year?

Could you do smth about Memristors? Or link me smth useful - I just heard about these and am not sure what to think of it.

This is an old theory and is simply not true. There is a sharp upregulation in the genes for the other coloured pigments, anthocyanins particularly. This may be for several reasons, but one theory is that these pigments are also antioxidants that help protect the tree from oxidants produced during programmed death of the leaf.

Wouldn't NOT raking them up be better as the organic matter would then return to the soil to be recycled by nature?

That's great guys but only a partial explanation - why are the autumn leaves a deeper red (and more colourful all round) some years? I seem to recall the summer's weather has something to do with it ....but it may have just all been a dream!?!

I leave... the leaves. The Earth can have 'em.

I've seen many people try to be poetic, talking about how the colorful leaves of autumn all about death... But I guess it's really more like a shark shedding its worn out teeth, so new teeth can grow in. >;-) But if you still want to be cuddly about it, just tell yourself the tree is just getting undressed before going to sleep.

They also reabsorb nitrates and phosphates from the leaves before abscission occurs...

I love his hair

I have a question I'd like to see you guys answer: If, for some reason, our blood were to reverse its flow direction, what exactly would happen? Step by step por favor. -E

Besides the green fading don't the reds and browns darken by accelerated oxidation since there's less water in the leaf?

I love this show, even if I know 75% of what it tells me I still learn stuff. I mean i just thought it was God telling us even death can be beautiful.

Just wondering but how come certain high pitched noises give people the goosebumps and really hurt your ears even tho they aren't really loud?

I have a QQ! What exactly is daylight saving and how does it work?

Misleading thumbnail ! All along i was expecting that man to give us the details. :P

Can you explain the reason of the particular smell when rains in dry soil?

I keep watching these videos even though I probably I don't retain any of the information lol

What makes things like glass, ice or plastic, transparent???

Why do peppers (or other fruits) go red yellow purple or green etc when ripe?

The guy in the thumbnail looks like Hank in 20 years.

can you explain how `Aquaman Crystal` works?

This may already have been asked before, but how regularly do supervolcanoes erupt on Earth? I've heard about Yellowstone's before, but rarely are others discussed it seems.

Doesn't he usually say "Subbable subscribers who keep these questions coming" not "answers" like he did today?

Question, we have some non-native deciduous trees around here whose leaves still fall off, but the only colors the leaves turn are brown and an ugly grey color. Why don't they turn red and orange like in other places?

In my garden there are two big birch trees that are almost touching each outer, but one of them lose it's leaves two full months before the outer one. Why don't they start losing their leaves at the same time?

What triggers the leaves to change color... temperature drop or a reduction in light absorption due to shorter days?

I have a QQ I'd like talked about sometime maybe, Why do helium inflated balloons deflate themselves over time if they are left alone and not untied?

I have hard this explanation before, but it doesn't make much sense to me. Before fall, leaves are extremely green, and during fall leaves are extremely red. If both pigments were present in those amounts during the summer, wouldn't the leaves look brown because there is both green and red present? Does the green somehow block out the other colors from being seen? Is more red produced once the green goes away?

He has such pretty eyes omg

Question- Is glass a solid or a liquid? Bets have been placed. Thanks!

If you close your eyes, you can clearly tell how much he sounds like hank. What do you call that accent?

Because the guy from the leaf raking stock photo was in the thumbnail, I though there was gunna be some guest specialist on the show...

"[beta-carotene] pigments are present throughout the year, but the red pigments, the anthocyanins, are synthesized de novo once roughly half of chlorophyll has been degraded." -wikipedia

In Tales of a Fourth Grade Nothing by Judy Blum a character explains that the trees in New York City do not change color because of all the pollution. Why does pollution keep the leaves green?

So why does the tree need to keep the leaves green. What function do leaves have besides shade from the sun?

I watched this video because I was like, 'Who's that guy in the thumbnail?'

SciShowians, answer this question! Should we rake leaves up, or allow them to decay to further nitrogen cycles and provide nutrients for the grass to spring forward stronger next spring?!

How does the tree stay alive through the winter? Does it go through a sort of hibernation?