The series “Imaginary Earths” speculates what the world could be like if one key aspect of life changed, whether associated with the earth or humanity.
Green skin is common in science fiction from little green men to Hera Syndulla from “Star Wars Rebels” to Gamora from “Guardians of the Galaxy”. But what if green skin weren’t only for fictional aliens? If humans had green skin, as an example, what if it granted us the ability to perform photosynthesis which plants use to live-off of sunlight?
Let’s analyze what science says about similar abilities in other animals & ask award winning science fiction author John Scalzi, how he thinks humans might hypothetically enjoy photosynthetic skin.
Every animal consumes-food to survive. In contrast, plants depend on photosynthesis to make their own energy. However, some animals use sunlight for a variety of capabilities.
For example, variety of animals benefitted from solar-powered molecules. The pea aphid produces pigments that with the help of light generate ATP (Adenosine Triphosphate), the compound that powers reactions with cells. Additionally, a stripe of yellow pigment on the exoskeleton of the Oriental hornet (Vespa orientalis) converts light to electricity, which could help to elucidate why these insects become more active during the middle of the day.
Other animals make use of actual photosynthesis using sunlight, water & carbon dioxide to produce sugars & other vital compounds. Plants & algae depend chloroplasts, structures within their cells, to carry-out photosynthesis, but Elysia sea slugs can steal chloroplasts from algae they graze on, to assist them live solely on photosynthesis for months.
Many other animals reap benefit from photosynthesis by forming partnerships instead. As an example, most corals partner with photosynthetic symbiotic microbes referred to as zooxanthellae, while the eggs of spotted salamanders receive valuable oxygen from algae.
If other animals can reap benefit from photosynthesis, could humans? If photosynthesis could work on humans, it remains uncertain what proportion of an advantage we could actually gain from it.
Plants can live-off of photosynthesis because they grow broad, flat leaves to harvest the maximum amount light as possible. They also need less energy because they’re far less active than animals.
According to Lindsay Turnbull, a plant ecologist at University of Oxford in England, if the skin of a typical adult woman were photosynthetic such as a leaf, the amount of surface area she had would satisfy only 1 percent of her daily energy requirements to survive. For a photosynthesizing woman to satisfy her energy demands, she would require a lot more skin, about a tennis court’s worth, Turnbull estimated.
In addition, photosynthesis needs carbon dioxide. Plants have pores called stomata that they use to supply the gas to their cells. Assuming that photosynthetic humans possessed chloroplasts, they could need porous skin to let in carbon dioxide, but such pores might let other things leak in or out, as an example, moisture in ways in which might prove detrimental to the physical body.
Still, if humans had photosynthetic skin, even a small benefit might prove useful. In John Scalzi’s Hugo Award nominated novel “Old Man’s War”, soldiers are equipped with genetically engineered bodies that not only possess cybernetic brain implants & enhanced strength, speed, senses, endurance & dexterity, but also green, photosynthetic skin.
Although, the soldiers of “Old Man’s War” cannot get all of the energy they have to survive from their photosynthetic skin, within the novel, they’re told it can “provide your body with an extra source of energy and to optimize your body’s use of both oxygen & carbon dioxide. The result: You’ll feel fresher, longer & better able to perform your duties.”
“I was thinking about how if you were to take the physical body into the chop shop, so to talk, to bling-it out, what would you do to it?” Scalzi said. Photosynthetic skin “would be a supplementary passive modification as opposed an active modification, you’ll just sit there & accrue benefits from it in terms of keeping energized. It’d be a 3% to 5% advantage in the scope of things, but that’s a margin you did not have before and you’re getting it for free.”
How might photosynthesizing feel? “I suspect it might desire being caffeinated all the time,” said Scalzi. “You would wake up & a bit like you’d say, ‘I need my coffee,’ you’d want to get some light.”
Assuming humans could successfully become photosynthetic, how might this alter the course of history if, say, “someone went back in time & gave Cro-Magnons access to a CRISPR machine?” Scalzi said.
Scalzi said, he doesn’t think human society would change radically if people could photosynthesize, given the marginal benefits it might provide. Still, the most energy dependent part of the body is human brain. “So i think that any surplus energy that photosynthesis might give goes to be haunted by the brain because it is a hungry, hungry, hungry organ,” Scalzi said “That might potentially mean societies might hit certain marks of progress a little bit faster, maybe reached the economic Revolution in 10000 BCE rather than 1800 CE.”
One might wonder, if photosynthetic people prefer little or no clothing. Although such people might receive a marginal boost from photosynthesis, if they moved to a desert area, they might likely have other resource issues to affect, like a scarcity of water, Scalzi said. “There’s always getting to be trade-offs,” he noted.
And would photosynthetic humans prefer little or no clothing, to soak up all those rays? In some photosynthetic societies, clothing might become a symbol of the elite, a sign they get enough energy from-food to not need photosynthesis. “You can imagine them saying, ‘I’m rich, so I can cover-up,'” Scalzi said.
So, would Scalzi want photosynthetic skin for himself? “On the grand list of body modifications, I want, it’s kind of in the lower middle,” he said. “It wouldn’t hurt, but I do not see the advantage from it being so substantial that I would completely change the way I’d look to benefit from it.
“But if somebody else is like, ‘I’m getting to be photosynthetic, then you do you,” Scalzi said. “I’m glad you’re happy.”