Could humans be bioengineered to use photosynthesis?


#1

Fascinating stuff.


#2

Not before we build giant human sized robots to fight wars with.


#3

Step 1 complete.


#4

Eh hem.

*and also develop faster than light space travel and have a dire need to force people to not eat food.

They’ve developed human photosynthesis in the anime I linked is all.

(also those robot’s aren’t giants, not anymore than a regular tank, and still smaller than a semi-truck)


#5

They also aren’t even robots, as they need a pilot. My roomba was more of a robot!

Mechs are still cool though and I can’t wait for the fight!


#6

I’ve heard of this series joked about around the web. Is it really worth watching?


#7

I liked it, but a lot of people can’t get past the animation style. Kind of an acquired taste, I guess. You won’t see a whole lot about the human photosynthesis, if that’s what you’re hoping.


#8

I think I’ll just keep re-watching Death Note and Code Geass for the rest of my life.


#9

I think Randall Munroe’s book “What If?” asks what if humans could photosynthesize. Maybe it was cows, I’m not sure.
This question has been asked before. The answer: If in the sun all day with 50% of skin exposed, you’d get 1% of your energy needs from photosynthesis.

Knights of Sidonia (Japanese fiction) imagines future space mankind to be photosynthesis-capable, eating 1 meal a week. This is pure fantasy. That will never be possible unless, through genetic engineering, energy needs are considerably decreased also.


#10

Watch Tokyo Ghoul next.

Make humans poikilothermic, and make that weekly meal ultra calorie-dense. Should solve the problem, keeping in mind that they’re living in space, so they can photosynthesise in small chambers with minimal solar filtering and very little atmosphere. The atmosphere is a huge limiting factor on the surface of the Earth.


#11

Couldn’t the photosynthesis be made more efficient instead?


#12

Looked through my copy and it isn’t there. It’s on his website.


#13

We could use purple bacteriochlorophyll instead of plant-type chlorophyll. But I think plant chlorophyll would be easier to integrate into human systems because it’s used within chloroplasts inside the cell, which don’t need to be babysat by the cell they’re in. But photobacteria carry out photosynthesis in the cell wall, so it must be regulated by the cell and the resulting energy must be received in a different manner. Wouldn’t say it’s impossible, but implementing it in eukaryotic cells would be a lot more complicated than just implementing chloroplasts. It could also end up being less efficient in eukaryotic cells than it is in prokaryotes, because of the differences in cell structure and metabolism.

Don’t think any enzymes could be developed to further increase the rate of photosynthesis since it happens on such a small scale and enzymes take up a lot of space…it’s already a pretty efficient process.


#14

I think the sheer fact we don’t have plants that get up, walk around, and hunt for prey is the reason that photosynthesis doesn’t work for “animals.” Anything that really uses photosynthesis is nearly incapable of movement.


#15

Not enough to make a difference. There just isn’t much energy in the light that hits our bodies.


#16

After giving it some more thought(but without incorporating any math for confirmation), I think that at the very least we would need to accomplish all of the following to make chloroplasts work as a primary energy source for humans(I’ve ignored other methods of photosynthesis because I’m less familiar with them and they’d be harder to implement)

  • Make humans ectothermic to drastically reduce our energy needs
  • Increase the surface area of our skin, perhaps by adding loads of rigid wrinkles and things like fins or skin growing in hair-like formations
  • Be naked all the time
  • Live in space, in completely transparent space ships
  • Invent a reliable universal cure for cancer(we’ll be getting a lot of it by exposing ourselves to so much solar radiation)
  • Incorporate endosymbiotic microbes in our lung tissues to extract nitrogen from the air
  • Take multivitamins every day
  • Consume a very large(probably around 10% of our body weight, for adults) calorie-dense meal probably once per week
  • never play sports, other than maybe eSports(though we may need a sugar drip to keep up with the energy demands of our brains)

I don’t think we could be considered human at that point, though…
Maybe photosynthesis might be better approached as a supplemental energy source rather than a primary energy source. Someone who’s a generally intact human who just has chloroplasts in their skin might not benefit much, though.


#17

On second thought lets stick with Soylent…

I must be crazy because a few hours ago I was seriously rationalizing this like “oh no biggie wed just need to be naked space amoebas.”