Theories on the Origin of Life

Study Notes

Spontaneous Generation: Living things arise from non-living matter.
- Aristotle, a prominent figure of this theory, believed everything contains a soul and matter generates life.
- Francesco Redi (1668) demonstrated that maggots emerge from flies, not decaying meat, refuting spontaneous generation.
- Louis Pasteur, through his swan-necked flask experiment, further disproved the theory.
Panspermia: Microorganisms from space could have traveled to Earth and initiated life here.
- This suggests life began from outer space, possibly carried by comets.
- Evidence supports the survival of bacteria subjected to high-speed forces, similar to conditions experienced by materials on Mars.
Primordial Soup Theory: Life originated from the combination of inorganic molecules present in a primordial soup.
- Oparin and Haldane (1929) proposed that initial compounds like hydrogen, water, ammonia, methane, and carbon dioxide existed on early Earth.
- These compounds were synthesized by energy sources such as lightning, volcanoes, and ultraviolet light, forming the building blocks of life.
- The Miller-Urey experiment attempted to mimic early Earth conditions in a laboratory setting, testing the theory of life emerging from inorganic matter.
- The theory hypothesizes the Earth's state approximately 4 billion years ago.
Abiogenesis Theory: Life originated from inorganic molecules, which recombined due to energy input (e.g., Primordial Soup Theory).

Atmosphere: Composed of oxygen, nitrogen, and carbon dioxide, crucial for sustaining life.
Water: Regulates temperature, supports aquatic life, and facilitates chemical reactions in living organisms.
Magnetic Field: Shields the Earth from harmful solar winds and cosmic radiation.
Plate Tectonics: Help recycle nutrients and minerals within the Earth's crust.
Distance from the Sun: Located within the habitable zone, where the temperature allows for liquid water on the surface.