The presence of water on our planet is essential for the development of life, but we have already located the precious liquid in different regions of the Solar System, and that ends its “local”. Instead, Earth is the only place where we can see fire. What makes this relationship unique? The folks at PBS Eons explain it.
The Sun is a giant hot ball of plasma. Jupiter's moon Io has more than 400 active volcanoes. Electrical storms are common in several regions of the Solar System. And yet... none of that equals fire. In fact, the only place we can find it is here, on Earth. Why does that happen? The folks at PBS Eons have the answer in their latest video.
Earth, Fire, Life: A Close Relationship
Of course, things were not always this way. Oxygen accumulated through a long process that ended with almost all life on the planet, but at the same time it completely modified its conditions and established the basic configuration necessary for fire.
In relaxed terms, fire requires oxygen and fuel... although not just any fuel. The combustion process breaks its original molecules and bonds them with oxygen, giving rise to new molecules as byproducts. The video indicates that this process reaches a higher level of efficiency when the fuel has multiple hydrogen and carbon bonds... like cellulose, the essential structural component of plants and the most abundant organic polymer on Earth.
Unfortunately, the available information about ancient plant species on our planet is not that good. Fossils reach 500 million years, but at the 430 million years mark, our record is more robust. The filaments Nematophyta, the spores Pachytheca, and the giants Prototaxites appear here. Prototaxites could grow up to nine meters, and although many of their details remain in the dark, what we do know is that they burned in the past. Coal samples suggest that Prototaxites attracted lightning.
During the Carboniferous (and its explosion of photosynthesis), with the beginning of the formation of Pangea and the absence of a chemical or biological process to “reintegrate” it into the biosphere, dead plants ended up buried in the geosphere (heat, pressure, and a few million years later, the result is coal). The excess oxygen in the atmosphere allowed insects to develop a terrifying size (anyone interested in a scorpion as big as a dog?), but also made forest fires gigantic.
Fire “accompanied” the new forms of plant life, and many of them learned to adapt. Pines are an excellent example: some species developed a thicker bark, others discarded lower branches, and then there are those that take advantage of fire, dropping their seeds on the ash-enriched soil.
Finally, “the asteroid” arrived, and Earth experienced fire on a scale never seen before, but no extinction is perfect: Earth recovered and gave space to prairies and steppes with their grasslands. These keep most of their anatomy underground, however, the upper part burns very well. All the tissue that dies accumulates on the surface, but fire cleans that material, returning nutrients to the soil and feeding the growth of the following season. At the same time, fire kills all competitors of the grasslands.
In summary, fire needs life, and for that reason it acts as a force to stimulate, diversify, and multiply the development of life in a large number of ecosystems. This relationship only works on Earth... for now.
