For about nine decades, scientists have been using the “primordial soup” theory to explain the origin of human existence. The theory suggests that some chemical reactions took place in a warm pond on the earth’s surface probably triggered by some external energy, like the ultraviolet rays, and gave birth to human life.
Recent researches have been counting on alternative theories suggesting that life either came from the deep surfaces, in the warm oceans or maybe in the space. Read below to find out more.
#1. Electric Spark
Yes, an electric spark is one of the probable theories that suggest how human life came into existence. Italian physician-physicist Luigi Galvani was conducting an experiment in 1771(or 1776) where in his assistant, in the midst of another experiment, accidentally touched an exposed sciatic nerve of the frog with a metal scalpel and that picked up a charge. At that moment, they saw sparks and the dead frog's leg kicked back with life.
It led to believe that the electric sparks generated amino acids and sugar out of an atmosphere filled with water, methane, ammonia, and hydrogen. The thunder further helped in the creation of building blocks of human life which eventually led to the formation of larger and more complex molecules.
(Image Courtesy: Universe Today)
#2. Community Clay
According to organic chemist Alexander Graham Cairns, the first molecules of life may have bumped into each other in the clay, and that might have helped the compounds to organize themselves in an organic pattern. This arrangement could be the way our genes are arranged today. He suggested that the mineral crystals present in the clay would have played a significant role in organizing the pattern.
(Image Courtesy: Science Daily)
#3. Deep-Sea Vents
Another theory suggests that life may have begun at the submarine hydro thermal vents which emit the hydrogen rich molecules. The rocky niches might have gathered all the molecules together and provided minerals to act as a catalyst for reactions to occur. These vents still constitute chemical and thermal energy to sustain vibrant ecosystems.
The theory was initiated long back and has been extended by Lane and William Martin from the Institute of Molecular Evolution at the Heinrich Heine University in Germany. He proposed that the rocky mineral walls deep down in the ocean-floor vents could have been a possible means for the beginning of human life.
(Image Courtesy: Origins of life)
#4. Chilly Start
This chilling theory suggests that ice could be the protector of human life. 3 billion years ago, the thick layers of ice must have been sheltering the fragile organic compounds against the ultraviolet rays and the cosmic effects. Under the ice protection, the molecules stayed long enough to react and give birth to human life. Lately, scientist Laura F. Landweber, Princeton University, also suggested that ice could have been a favorable environment to produce the first self-replicating molecules.
(Image Courtesy: The Daily Galaxy)
#5. RNA World
The RNA theory was first suggested by Alexander Rich in 1962 and was later coined by Walter Gilbert in 1986. The theory suggests that DNA needs proteins to form, and proteins require DNA to form, which implies the need of another source helping these two to form. Thus, the theory of RNA came into existence as it stores information about DNA and acts as enzymes like the proteins. Some scientists suggested that RNA arrived on earth spontaneously while others suggested that other nucleic acids such as the PNA or TNA occurred before RNA.
(Image Courtesy: Bioninja)
This theory makes you think ‘out of the planet.' Yes, the theory suggests that perhaps earth was not the original breeding ground for human life. Just like the meteors that break due to cosmic impacts and fall on Earth, similarly some meteors might have brought with them microbes which created humans in the form of Martians. A researcher Svante Arrhenius suggested this, followed by others like Sales Gyon de Montlivant, who proposed that life came from the moon and H.E. Richter, who suggested that life came from meteorites.
(Image Courtesy: Slideshare)
#7. The Deep-Hot Biosphere Theory
Thomas Gold proposed a theory suggesting that life began far below the surface due to a continuous supply of Aboriginal methane from the Earth’s mantle. He suggested that microbial life is spread all over in the porosity of the Earth's crust, where rising temperatures set a limit. He ridiculed the earlier primordial soup theory saying that if life began in a small warm pond, then it would have run out of food sooner.
(Image Courtesy: Orion's arm)
Have you ever come across any such interesting theories? Let us know in the comment section below.