If animals evolved from plants, why did they give up their ability for photosynthesis?

Question

I am not aware about the truth status of the if statement. But seriously - wouldn't that be much more practical than eating other stuff?

Answer 1

Animals did not evolve from plants, we had a common anscestor, back in the single cell days a few billion years ago. Then, some single cell organisms became plant-like blue-green algae (they have a new name now - not sure what it is) by forming a symbiotic relationship with chloroplast-like bacteria. Some others formed into amoeba like organisms by engulfing and forming a symbiotic relationship with mitochondrial-like bacteria, and became early animal-like organisms.
You're right, it would have been simpler to all have remained plants, and taken all our energy from the sun. Evolution favours survivalists, after all. But it is thought that amoeba-like organisms may have first arisen where there was little sunlight, say under the water, where having chloroplasts would only help in shallow water during daylight. Any organisms which didn't need light would benefit by scooting around eating things at night. Hence mobility might also have been an advantage, and would have been favoured for survival.

Good question.

Answer 2

Plants and animals did have a common ancestor, but it is thought that Chloroplasts (the organelle that allow plant cells to use photosynthesis) did not exist until after the future plant and animal lineages diverged or split up. There is tremendous support for the Endosymbiont Hypothesis, which you can ask about if you want more detail, but basically, the idea is that some cells phagocitized (surrounded as if "eating") some smaller cells, which eventually became symbiotic and are today's mitochondria and chloroplasts. The chloroplasts did not enter into cells until the cells which would become animals were already different that the cells which would become plants, or maybe this was one of the differences that lead to this divergent evolution.

Everything had a common ancestor, LUCA, but the ability to turn light into food wasn't always around, animals never had it to lose.

Answer 3

animals evolved from plants or not.. i do not know for sure.

but this thing that you ask.. "But seriously - wouldn't that be much more practical than eating other stuff?"

its not about the enough energy or not question.. it is the rate of photosynthesis.. it is pretty slow..and at the rate at which photosynthesis takes place, if animals were to produce food and gain energy, they'd have to wait for ages to produce energy required for every movement of theirs! practically, plants dont move except for the wind making it move!!

and, if animals had to photosynthesise:
1. they have to be green all over so that the chloroplast pigment carries out the job
2. they have to have connection to the soil (like roots) to pick up the minerals necessary

so if all these happen practically, who will eat the plants, and who will eat the animals that eat plants and how will the ecological balance be maintained?? it's practical now isnt it??

Answer 4

Animals didn't evolve from plants.
Here is what happened.
Long ago, all the organisms were photosynthetic.
They took in CO2 and H2O, and made sugar and Oxygen.
Pretty soon, there was a ton of Oxygen in the atmosphere.
Evolution led to the making of Organisms that consumed Oxygen, and didn't make any Oxygen, like the photosynthetic organisms.
Animals evolved from these O2 consuming organisms.
Plants evolved from the photosynthetic bacteria.

Answer 5

Animals did not evolve from plants. Both animals and plants derived from microorganisms. When the microorganisms split into autotrophic (make their own food) and heterotrophic (must consume other things), these cells soon formed the more complex organisms that seemed to mirror their behaviors. Animal cells beget animals, plant beget plants. Functions form functions.

Answer 6

Animals didn't evolve from Plants... they evolved from single celled organisms! No chloroplasts with chlorophyll in animal cells therefore no photosynthesis! :)

Answer 7

Who says they did give it up? We don't use the sun to make food, but we do use the sun for warmth. Cold blooded creatures are not the only ones to sun bathe. Any energy we don't have to use to keep warm is energy we don't have to consume. Obviously there are limits.

Answer 8

animals didnt evolve from plants they evolved from organisms

Answer 9

animals did not evolve from plants, thats one man's opinion. and yes darwin was insane

Answer 10

never happened