What If Humans Could Photosynthesize?


How cool would it be if you could photosynthesize? No more cooking or grocery shopping. If you got hungry, all you’d need is some
tasty sunlight! It sounds awesome, but it turns out that it’s
not so easy being green. Photosynthesis allows plants to take sunlight
and carbon dioxide and turn it into sugar, which they use for food. Oh and it also makes oxygen, which is good
if you like breathing and all. So it sounds simple enough. You sit in the sun and BAM you have a food
supply. Let’s get into the mechanics of photosynthesis. Chloroplasts are cute little organelles in
plant cells that make photosynthesis happen. They contain the molecule chlorophyll, the
stuff that makes plants green. More importantly, the chlorophyll captures
the sun’s energy. Plants are green because chlorophyll is especially
good at absorbing blue and red light, while green and yellow light gets reflected back
to your eye, which is why they, you know, look green. If we had to photosynthesize, we’d need
chloroplasts. So we’d be green. Pretty awesome. So you got your chlorophyll and you’re soaking
up some rays. But it’s not a very efficient process. Estimates vary, but plants only convert about
5 to 9% of the total available energy from the sun’s rays. Since photosynthesis is pretty inefficient
at converting sunlight into energy, we would need to absorb a LOT of light. Plants evolved broad, flat leaves to increase
their surface area and maximize the amount of sun hitting their chloroplasts. So we’d need leaves. Great. We’ll be able to get plenty of sunlight,
but now we run into another issue. Our skin. That thick, oily layer of dead skin cells
covering our entire body would need some adjusting. It prevents carbon dioxide from getting to
the cells in our body. We do exhale CO2 as a waste product, but that
CO2 is mainly produced around the brain and in muscles. To photosynthesize, we’d need carbon dioxide
near the surface of our sk0in. And we’d need a lot more of it than we produce,
so our skin needs to be more porous–like 100 times more porous! That would allow plenty of CO2 in for our
human photosynthetic needs. Carbon dioxide is crucial in photosynthesis. We won’t get too deep into it, but here’s
roughly how it works: Chlorophyll absorbs sunlight. The sun’s energy splits water molecules,
knocking electrons into motion through the chloroplast. This kicks off a series of reactions that
creates molecules that store energy, the most famous one being ATP. The split water molecules also release the
oxygen that we humans need to breathe. Good work plants! Now the plant pulls in carbon dioxide from
the air. Those energy molecules help put carbon dioxide
and the hydrogens from water together in the Calvin Cycle, making sugars like glucose,
the sweet, sweet sugar that feeds plants. But these sugars wouldn’t give us enough
energy to get up and move around. Trees use a lot less energy than us. A typical tree consumes around 200 calories
a day. A typical human consumes around 2000 calories
a day, since we need more fuel for our big needy human brains and for walking around. So we probably wouldn’t make enough energy
from photosynthesis to power our usual high energy human activities. Unless you count watching Netflix. So for us to photosynthesize, we’d be green,
need leaves, have weird porous skin to let CO2 in and we’d have to lie out in the sun
and not move much. Okay that last part doesn’t sound too bad. We’d still have to eat food to get the proteins
the human body requires, but we’d be good on the sugars and fats. Overall photosynthesis doesn’t seem to be
the way to go for humans. But it does work for some sea slugs and giant
clams. These guys eat photosynthesizing algae or
bacteria and use their chloroplasts to make sugars for them to use. So don’t humans do that? Well, scientists think it’s just not worth
it. The energy we would spend to feed and manage
photosynthetic symbionts is better spent foraging and taking care of our other biological needs. So just get the salad. And marvel at the chemistry that keeps life
going. Would you want to photosynthesis? Let us know in the comments. And check out some more plant filled science
while you’re here. Thanks for watching!

64 Comments

  1. ShiurKahn2 said:

    Erste

    August 30, 2016
    Reply
  2. Allyson Gail said:

    0:51 over it

    August 30, 2016
    Reply
  3. Kaleb Harding said:

    Isn't there people that actually try to do photosynthesise though

    August 30, 2016
    Reply
  4. Corvus said:

    Fuck it, let's just eat the shit photosynthesizes instead.

    August 30, 2016
    Reply
  5. John Smith said:

    But we do photosynthesize….I'm being serious, watch this video!

    https://www.youtube.com/watch?v=FqDDfslIMyQ

    August 30, 2016
    Reply
  6. Bladeninja76 said:

    Nice concept and video.

    August 30, 2016
    Reply
  7. Marina DU said:

    The trypophobia 😂

    August 30, 2016
    Reply
  8. aquabarbie said:

    Great video! I've always said that humans should be able to photosynthesize, but this explains it all. God made us the way we had to be made.

    August 30, 2016
    Reply
  9. Citric Thoughts said:

    It would definitely be worth it to use a minimal alteration form of photosynthesis. No leaves, no porous skin, instead have the Co2 absorbed from the bloodstream. Why? Because famines happen, and green skin that makes a bit of energy from sunlight would help a lot of people survive fairly harsh conditions. While the energy intake would be pretty minimal it would be better than nothing. Also those minimal changes wouldn't mess with our normal lifestyles too much. It'd just be a small but healthy bonus that would help us live better.

    August 30, 2016
    Reply
  10. foobargorch said:

    The snail's name: Elysia chlorotica. It occurred to me a while ago that it might be possible to replace mitochondria with chloroplasts, and then I googled and discovered that snail. Awesome! Nature always seems to surpass the imagination.

    My thoughts along this, still basically in the realm of scifi, but c.f. the research of Dr. Victor de Lorenzo is certainly a promising stab in this direction. The problems you raised can be optimized somewhat with the power of magic science from the future:

    Much like C4 or better yet, CAM photosynthesis plants use membranes to enrich RuBiSco with CO2, humans could do that in a way that would be more compatible with their normal skin functions..

    Also, Chlorophyll is kind of lame, there's a lot more energy to be captured, specifically the green part of the spectrum, and UV as well.

    Imagine bacteria that colonize your skin cells, helping to create more translucent skin, substituting melanin for generalized chlroplasts that functions like mitochondria more or less. It's not so far fetched.

    As a food source it's dubious though, even with optimal solar exposure it's not enough to sustain a human (I estimated about 2/7th of daily calorie requirements are the theoretical maxmimum, but don't remember what I based that on). I thought the interesting feature of this would be conserve metabolic water and get better local oxygen/CO2 management like on some crazy trek through the desert Dune scenario, and better cancer protection.

    Who knows, maybe if we really botch this global warming thing we'll all be wearing bio-sunscreen in a few years =)

    August 30, 2016
    Reply
  11. Irun Mon said:

    God I love this channel, you answer many of my questions, keep the good work guys 🙂

    August 30, 2016
    Reply
  12. TheSweetOldMan said:

    Green chicks…now that's hot. With my luck they would probably tell me to leaf them alone. 😉

    August 30, 2016
    Reply
  13. LOVE OF PLANTS 🌻 said:

    Plants make me green with envy.🌿

    August 30, 2016
    Reply
  14. Tummywubs said:

    So… you basically become Shrek…

    August 30, 2016
    Reply
  15. ploi bates said:

    What happened you swallow something but it goes into your breathing tube?

    August 30, 2016
    Reply
  16. Adam M said:

    Is cute a scientific form?

    August 30, 2016
    Reply
  17. Racially Ambiguous said:

    I have to disagree with some of the points made in this vid. It seems the vid was made with a "What if humans were plant hybrids" mentality which is not what the title asks.

    The green coloring makes sense, but not the leaves and pores.

    Plants need leaves to increase surface area, however humans really don't. Plant stalks are either thin, or like trees, don't have the ability to make energy in their trunks. If the chloroplasts were in our skin that would mean that any exposed skin would produce energy. Humans would just be a bit more naked is all. The amount of surface area would be rather large. Also, photosynthesis would not be the only energy source. There are plenty of examples of plants and microorganisms that are both photosynthetic and heterotropic. Meaning we would still eat plants and animals, with photosynthesis augmenting our energy gains.

    Arthropods like insects do have air pass in and out of them through pores like plants, but large animals like humans have lungs. We can intake large quantities of surrounding gasses to include carbon. Our circulatory system would be fitted to move said carbon to where it is needed just like our blood cells do oxygen.

    So, you guys got one out of three, which for a science channel is actually pretty bad unfortunately.

    August 30, 2016
    Reply
  18. YASH said:

    what if somehow we made the process way more efficient, like 80% or more? it may not eliminate the need for food, but decreasing the demand would still be a good deal.

    August 30, 2016
    Reply
  19. sooooooooDark said:

    so is hulk stronger at day?

    August 30, 2016
    Reply
  20. David Villafuerte said:

    why is there weed in 2:58

    August 30, 2016
    Reply
  21. Firaro said:

    Is there perhaps a more efficient way to photosynthesize that evolution didnt choose but could be engineered?

    August 30, 2016
    Reply
  22. max iwaniec said:

    Yes, I actually plan on working on it.

    August 31, 2016
    Reply
  23. Your Majesty said:

    I wish this was possible because groceries are expensive, I've been eating bananas all day

    August 31, 2016
    Reply
  24. viki digi said:

    instead we have a more efficient way i.e breathing and we can take enough energy to lie walk run and do other things just by breathing air and converting it into food its called breath-ism

    August 31, 2016
    Reply
  25. Lily Cho said:

    i know its a cartoon, but can we think about what makes poison ivy, the batman character, more mobile than most plants?

    August 31, 2016
    Reply
  26. William Adkins said:

    "We'd need leaves," or like, we would have smaller clothing?

    August 31, 2016
    Reply
  27. Alan R said:

    2:56
    premise: 7
    explanation: 8
    plant choice: 10

    September 2, 2016
    Reply
  28. Lucas Vegen said:

    Everything in relative, was covered, except the Human equivalent of Chlorophyll. Is this Melanin?

    September 2, 2016
    Reply
  29. bRenegadez said:

    Isn't Melanin the same as chlorophyll tho..so black ppl can actually photosynthesize

    September 3, 2016
    Reply
  30. John T said:

    I didn't know that plants use adenosine triphosphate or ATP for energy like animals. Interesting…

    September 4, 2016
    Reply
  31. Ms. Jones Science said:

    darn… I really planned on finding a way for humans to photosynthesize :/ I guess I should not do that lol

    September 9, 2016
    Reply
  32. My Green Pets said:

    Cannabis at 2:57 🙂

    December 19, 2016
    Reply
  33. NukeML said:

    What if we both photosynthesize and eat?

    January 15, 2017
    Reply
  34. Alekai said:

    If you eat a ton of chlorophyll rich food you can actually photosynthesize a small amount of energy.

    March 27, 2017
    Reply
  35. Tony Mondola said:

    So… obviously there was no research done on melanin by this channel. You know… the reason black people have a physical advantage over less pigmented individuals. It is literally the only reason why.

    March 31, 2017
    Reply
  36. Retro Electro said:

    Say you tried to live in the sun?

    March 31, 2017
    Reply
  37. JamesSkuzz said:

    I must be Jesus cause I have this super power that allows me to get vitamin D from the sun. But wait! That doesn't make scientific sense! Except it's true any way.

    April 24, 2017
    Reply
  38. Red Broccoli said:

    Nicely researched! I would always try to suggest or see what would happen if humans could photosynthesize and never got the answer from anyone, this video answered most of my questions! Could you made a video on how to would humans be able to photosynthesize in the first place? Like my idea was to add a chloroplast in the egg cell, then I thought of what if it divides, would the chloroplast still be present too, and I tried thinking of the other cells, what would happen to them or the chloroplast, would it just not function due to no photons. Also can we discover or come up with a genetic sequence to make us have chloroplasts nonetheless? I mean I understand why we wouldn't need it, but is it still possible we can get them?

    November 29, 2017
    Reply
  39. SnowmansApartment said:

    really don‘t like that voice tho.. 😖

    November 30, 2017
    Reply
  40. Aymen Coucou said:

    why do we not make a genetequly made plant that has better photosynthes

    January 15, 2018
    Reply
  41. Rise_Panther Tv said:

    We wouldn’t have hair

    July 5, 2018
    Reply
  42. piyush singh said:

    Mst

    August 13, 2018
    Reply
  43. اللعنة عليك said:

    We would release carbon dioxide as well as release oxygen

    August 17, 2018
    Reply
  44. Will Allinson said:

    I’ll take photosynthesis over cellular respiration any day if it gives me an excuse to lie around all day.

    September 18, 2018
    Reply
  45. TamTheMeerkat GD said:

    Would it be funny if I photosynthesize using zoochloroplasts? ( ͡° ͜ʖ ͡°)

    October 12, 2018
    Reply
  46. Alina Davydov said:

    i would love to!

    October 26, 2018
    Reply
  47. Chi Pa Pa said:

    So instead of Humans, it will be Namekians.

    December 6, 2018
    Reply
  48. Chicken 'n' coke said:

    What did the teacher say to the kid

    Read more

    March 2, 2019
    Reply
  49. Tristan Larson said:

    i hate this video

    March 26, 2019
    Reply
  50. jmike700 YT said:

    Shrek?

    April 29, 2019
    Reply
  51. Toaster Bagels said:

    1
    2
    3
    4
    5
    6
    7
    8
    9
    0

    May 2, 2019
    Reply
  52. Eva said:

    Yes, I actually already can photosynthesize, this video must be soooo old. You may as well call me a sunflower. 🌻🙃

    May 18, 2019
    Reply
  53. Deepali Mittal said:

    this is a good video and i understood it well👍👈✌🎒🏫

    June 14, 2019
    Reply
  54. Qi Ai said:

    I want the ability of photosynthesis. I'm sick of eating and having constant digestive issues. If only, algae smoothies would do the trick, I'd be on it.

    June 17, 2019
    Reply
  55. SpiritualOpportunism said:

    Sims dude

    September 9, 2019
    Reply
  56. Adam I said:

    What if humans found a way to take chloroplasts in a pill

    October 16, 2019
    Reply
  57. Adam I said:

    Imagine being able to walk outside for 30 min and not have to eat

    October 16, 2019
    Reply
  58. Thomas Abbott said:

    canibals

    November 6, 2019
    Reply
  59. Garrett Reily said:

    no I do not

    November 8, 2019
    Reply
  60. Garrett Reily said:

    g cgfku gierhkfrehkiuferh gergh wejrhgywerh teu y gue rfhe kuye t orhgiu ehtiht iuwtl wyiywrt uier ok

    November 12, 2019
    Reply
  61. Garrett Reily said:

    iwefeueqehddibvohdwfjjfdddddfdfijoijiojfhvvvhuiuhhufvhu

    November 12, 2019
    Reply
  62. Garrett Reily said:

    This week Reactions takes a look at the chemistry required for a human to photosynthesize. Ohh the sunny science! The sun shines a massive amount of energy onto the Earth’s surface every day. What if people could take a cue from plants and use sunlight to make their own food? From chloroplasts to carbon dioxide, Reactions creates a hypothetical photosynthetic human and gives a quick crash course on the chemistry of photosynthesis.

    Find us on all these places:
    Subscribe! http://bit.ly/ACSReactions
    Facebook! http://facebook.com/ACSReactions
    Twitter! http://twitter.com/ACSReactions
    Tumblr! http://tumblr.com/ACSReactions

    Touch Me – Pure Natural
    Good Starts

    Producer:
    Elaine Seward

    Writer:
    Sam Lemonick
    Elaine Seward

    Executive Producer:
    Adam Dylewski

    Scientific consultants:
    Todd Breslauer
    Kyle Nackers
    Darcy Gentleman, Ph.D.

    Sources
    http://www.nature.com/scitable/topicp...
    http://www.nature.com/scitable/topicp...
    http://oceanexplorer.noaa.gov/facts/r...
    http://www.bbc.com/news/science-envir...
    http://blogs.plos.org/retort/2010/12/...
    http://www.rsc.org/Education/Teachers...
    http://www.newscientist.com/article/m...
    https://docs.google.com/document/d/1C...
    http://rstb.royalsocietypublishing.or…

    Ever wonder why dogs sniff each others' butts? Or how Adderall works? Or whether it's OK to pee in the pool? We've got you covered: Reactions a web series about the chemistry that surrounds you every day.

    Reactions is produced by the American Chemical Society.
    This week Reactions takes a look at the chemistry required for a human to photosynthesize. Ohh the sunny science! The sun shines a massive amount of energy onto the Earth’s surface every day. What if people could take a cue from plants and use sunlight to make their own food? From chloroplasts to carbon dioxide, Reactions creates a hypothetical photosynthetic human and gives a quick crash course on the chemistry of photosynthesis.

    Find us on all these places:
    Subscribe! http://bit.ly/ACSReactions
    Facebook! http://facebook.com/ACSReactions
    Twitter! http://twitter.com/ACSReactions
    Tumblr! http://tumblr.com/ACSReactions

    Touch Me – Pure Natural
    Good Starts

    Producer:
    Elaine Seward

    Writer:
    Sam Lemonick
    Elaine Seward

    Executive Producer:
    Adam Dylewski

    Scientific consultants:
    Todd Breslauer
    Kyle Nackers
    Darcy Gentleman, Ph.D.

    Sources
    http://www.nature.com/scitable/topicp...
    http://www.nature.com/scitable/topicp...
    http://oceanexplorer.noaa.gov/facts/r...
    http://www.bbc.com/news/science-envir...
    http://blogs.plos.org/retort/2010/12/...
    http://www.rsc.org/Education/Teachers...
    http://www.newscientist.com/article/m...
    https://docs.google.com/document/d/1C...
    http://rstb.royalsocietypublishing.or…

    Ever wonder why dogs sniff each others' butts? Or how Adderall works? Or whether it's OK to pee in the pool? We've got you covered: Reactions a web series about the chemistry that surrounds you every day.

    Reactions is produced by the American Chemical Society.

    November 12, 2019
    Reply
  63. Garrett Reily said:

    no

    November 12, 2019
    Reply
  64. Sammy Thomason said:

    Am I the only one that’s a weird lizard creature and likes to set in the sun and likes to take long hot showers so I can bask in the heat

    November 25, 2019
    Reply

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