(NaturalNews) In order to feed ourselves, human beings have to grow, hunt or gather food. Many other living things don't have those kind of sustenance limitations because they can create their own through the process of photosynthesis. Plants, algae and several species of bacteria can do that by using sunlight, which creates chemical reactions in their bodies and producing sugars.
Is it possible for humans to do that - to alter our bodies to feed off the sun's energy as a plant does?
As a rule, animals aren't able to achieve photosynthesis but, as scientists have noted, all such rules tend to have exceptions. The latest potential exception, in fact, is the pea aphid, an enemy of farmers but an ally to geneticists, the BBC reported recently.
In August, Alain Robichon of the Sophia Agrobiotech Institute in France, noted that the aphids use pigments called carotenoids to utilize the sun's energy to manufacture ATP, a molecule that acts to store chemical energy. The aphids are among a very few number of animals that are able to make these pigments for themselves; they do so by using genes stolen from fungi.
Green aphids, which contain lots of carotenoids, produced more ATP than white aphids which have almost no carotenoids, while orange aphids containing an intermediate amount of carotenoids made more ATP in sunlight than in darkness.
Not true photosynthesis, but...
The BBC report said another insect, the Oriental hornet, may be able to accomplish something similar, using a different pigment called xanthopterin, which converts light to electrical energy.
Both insects may be using their ability as a back-up generator of sorts, providing them with energy when supplies are low or demand is high.
However, both cases are controversial, the report said, as the details of just exactly what the pigments are actually doing remain unclear. Also, neither is a true form of photosynthesis, which also involves transforming carbon dioxide into sugars and other compounds. The use of solar energy to accomplish that is just part of the entire conversion process.
But there are animals that photosynthesize in every sense of the word, and each of them does so by forming partnerships, scientists have learned. Corals are a perfect example; they are a collection of hundreds and thousands of soft-bodied animals that are similar to sea anemones, living on large, rocky reefs of their own design and making. These creatures depend on microscopic algae called dinoflagellates that live within certain compartments in their cells.
"These residents, or endosymbionts, can photosynthesise and they provide the corals with nutrients," said the report.
Researchers note that some sea anemones, clams, sponges and worms also have photosynthetic endosymbionts, and they are joined by at least one species with a backbone: the spotted salamander.
"Its green-tinged eggs are loaded with algae, which actually invade the cells of the embryos within, turning them into solar-powered animals," said the report. "The algae die as the salamanders turn into adults, but not before providing them with a useful source of energy in the earliest parts of their lives."
One step closer
But how close, really, are humans to being able to perform such feats? Closer, perhaps, than you might think.
Last year, Christina Agapakis, a synthetic biologist from the University of California-Los Angeles, was able to get a baby zebra fish to accept photosynthetic bacteria, just by injecting them into the fish when they were still embryos.
"The biggest surprise was that nothing happened," she wrote on her blog. Though the fish cannot photosynthesize, neither did they reject the bacteria.
"Agapakis' experiment showed that back-boned animals can, at the very least, tolerate the presence of photosynthetic microbes, or the type that fuels the baby salamanders. And with a little tweak, she even persuaded the bacteria to invade mammalian cells," said the report.