Q1/3 W6 Beginning of Life

Hypotheses on the Origins of Life

Panspermia Hypothesis

Primordial Soup Hypothesis

Deep-Sea Vent Hypothesis

Panspermia Hypothesis

• Life’s building blocks, or simple microorganisms, might have come from space.
• Comets, asteroids, or meteorites could carry organic molecules that survive the journey through Earth’s atmosphere and land in oceans.

• While it doesn’t explain where life began, it suggests that life’s ingredients might be common throughout the universe.
• Evidence: Scientists have found organic molecules, including amino acids, on comets, asteroids, and meteorites, suggesting that some of life’s building blocks could have arrived on Earth from space.

Deep-Sea Vent Hypothesis

• Life may have begun around hydrothermal vents, which are cracks in the ocean floor that release superheated, mineral-rich water.
• These vents provide both energy and chemicals, like hydrogen, methane, and other simple molecules, that could serve as building blocks for life.

• Tiny pockets in surrounding rocks may have protected early molecules as they formed complex organic molecules, like amino acids and simple sugars.
• Evidence: Microbial life exists around modern hydrothermal vents, and lab experiments show amino acids and other organic molecules can form under vent-like conditions.

Deep-Sea Vents

Primordial Soup Hypothesis

• Life may have started in shallow oceans or ponds filled with a mix of simple chemicals, called a “primordial soup.”

• Energy from lightning or sunlight caused these chemicals (like methane, ammonia, and water) to react, forming amino acids (small molecules that are the building blocks of proteins/life) and other organic molecules.

• Over time, these molecules could combine into more complex forms, eventually leading to life.

• Evidence: The 1953 Miller-Urey experiment recreated the conditions of early Earth and showed that amino acids could form naturally in the lab.

Scientist, Harold Urey

Miller-Urey Experiment Setup