You need additional structure to support the surface area. Then you need it to move somehow because otherwise it can’t drift in the wind. And if it can’t drift in the wind it needs big muscles to be able to move like an animal.
I’m done debating this topic as well. I’ll only return when someone does what I said in the underwater thread: makes a full explanation from start to finish with actual math showing that the species they envision is actually possible.
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All im saying is keep chloroplasts in the later stages, and I WILL make something that works.
you wont, because like hhyyry said, photosynthesis is just a bad idea for a sentient creature
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Personally, I think that having a 5 square meter leaf for a body and being able to fly both defeat the purpose of evolving high intelligence. A lot of human (and non-human, e. g, New Caledonian crow) innovations were made in order to gather and process food and resources. If you can simply make your own food, there’s little need for problem-solving.
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Outside factors can contribute to the intelligence. I’ve been reading up on potential plant sentience/sapience, and there is evidence that plants are currently sentient, on earth.
For the problem solving, as an example there is a plant that to survive cold nights, it photosynthesizes and then does complex arithmetic to determine how much starch to store in different areas of itself so it can survive the night. By the morning, 95% of it’s starch has been consumed
So just because you can make your own energy doesn’t mean you have no need for problem solving, as outside dangers can contribute to the need for problem solving
Division doesn’t require a conscious brain to calculate. Very complex mathematical systems can be found throughout nature, and even inanimate objects like rocks or sand can “solve” mathematical problems without actually thinking (for example, crack propagation in stone tends to follow the most energy-efficient pattern, which is why basalt pillars are hexagonal in shape).
You make a good point that plants react to their environment very readily, though. I have no doubts about that. Plants on earth are able to do amazing things, such as communicating and sharing nutrients via fungi, mimicking their environment, and even detecting sound from flying insects via their flowers. Slime molds are probably good to mention here too, they can perform remarkable tasks for an organism without differentiated tissues/organs. I’m just not sure what the selective pressure for such an organism to invent spears or axes would be, though.
Regarding non-sophont organisms, though, I think mixotrophy is very viable and am surprised there aren’t more examples of photosynthetic animals (besides corals and that one chloroplast-stealing sea slug).
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Actually, many species of salamander do photosynthesis (kleptoplasty), and one species of wasp can convert sunlight into electricity
Oh, right. I did actually remember those, I’m not sure why I didn’t mention them.
I’m not really sure if the oriental hornet counts as photosynthetic, though, because I didn’t see anything about it using the energy to make food (and if we’re stretching the definition past that it sort of starts to fall apart, since plenty of animals need the sun to warm themselves and there are other compounds that are synthesized using sunlight, like vitamin D).
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Also chloroplasts are very heavy, so it would be hard to move.
Let’s do some more calculations
Photosynthesis has a theoretical maximum efficiency of 30%. Let’s assume a figure of 20%, which seems reasonable enough
The closest an Earthlike planet can be to its star, assuming all else is like Earth, seems to be around 0.6 AU. This, assuming light follows an inverse square and that a similar proportion is lost, then this planet receives around 2.8kW/m^2
Assuming a 20W brain, then the area required for this species comes out as around 360cm^2. This seems like quite an achieveable area for a leaf
where did you get 30 and 20 from?
and did you read the wikipedia page?
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The sources I found disagree, but seem to also provide 8-9% as the more realistic higher end whilst 12% or so is the theoretical maximum. Using the lower of the two higher end realistic values for an earth like world’s flora’s photosynthetic efficiency we can plug 8% into the equation provided earlier by hhyrlylainen.
340 * 0.08 = 27.2
100 / 27.2 = 3.67647058824
Yikes. Still not the best considering that’s nearly double the surface area of an adult male human (1.9m^2)
So what about if we plug in the theoretical maximum instead?
340 * 0.12 = 40.8
100 / 40.8 = 2.45098039216
And that looks a lot better, seeing as that is only %128.998968008 of the surface area of a human, and the photosynthetic surfaces could probably also serve as an equivalent to skin.
Anyway, so theoretically possible? Maybe. Probable? Unlikely. I can think of a couple possibilities for how it could evolve a brain though presuming it can even be done, and also a method of reducing the immediate power requirement of the early brain prior to developing humanlike intelligence: Human brains did not appear overnight, but evolved slowly, and there exist many smaller designs for brains used by less intelligent organisms which would most likely be cheaper as an intermediary option.
Additionally, certain trees can in fact possibly move. Socratea exorrhiza exists. Although certainty on that one is dubious.
Edit:
And as for why a brain would be useful, defense. Can’t be eaten by herbivores as easily if you can defend yourself.
Please do not double post. In your second post you did already find out how to edit posts.
I’ll combine your posts myself this time.
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I think the most probable way a photosynthetic “critter” could come about is as a fruiting body that wanders until it detects good soil quality and few competitors. They would most likely have high:protein, high fiber tissues attached to a sort of acorn like cap for structural support. They’d move like Kirby and probably evolve over time to have brains. From there it’s speculative nonsense as as opposed to speculative semi-sense but I think it’s possible for them to develop ways for the information stored in the brain to be passed on from fruiting body to stationary plant to next generation or fruiting body. Intelligence cod evolve as millions of years of experience searching for good spots, living in said spots, and avoiding predators would make for very smart creatures. They obviously couldn’t store millions of years of memories but they’d keep all the skills and any life lessons. I have no idea why such a creature would develop tool use, perhaps fruiting bodies would travel in groups and some would grow while others defended the saplings until the oldest saplings could make more fruiting bodies and the cycle could repeat? In a setting like that stick or stone walls, or pit traps or spears are all viable, but I don’t see how that would work. Honestly the only viable plant civs in my mind are the piggies from speaker for the dead.
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They would be able to jump over 2 times their body size?
Maybe later on via spasmatically jittering
Quoting this and putting it here so it is in the right topic as well
So you are bringing in the point that we could potentially see plants which take on a secondary role as detritivores followed by a gradual transition in which the supplementary source of sustenance becomes progressively more important as the original is simultaneously phased out? As this happens, it loses the ability to be completely an autotroph whilst retaining photosynthetic capabilities as a supplement?
Did I understand that correctly?
Almost - not exactly a detrivore like worms - think more like scavengers, flies and buzzards. These plants would dig through the soil a little for food and nutrients, but gather most of what they need from carcasses.
Also, not so much they lose their ability to synthesize - just that it would no longer be the only source of energy they need to survive (and so I try to fix the lack of caloric intake issue)
But yeah you pretty much got it right
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