The idea that life could have originated through chemical evolution in a primordial atmosphere was demonstrated experimentally in the laboratory by which scientist?

Introduction / Context:
One of the classic questions in biology and general science asks how life might have originated on Earth. The chemical evolution theory proposes that simple inorganic molecules in the early Earth atmosphere could gradually form organic molecules, which then led to the first living systems. A famous laboratory experiment provided strong support for this idea by synthesizing organic compounds under simulated early Earth conditions. This question checks whether you can identify the scientist associated with that experiment, which is an important part of origin of life discussions in textbooks.

Given Data / Assumptions:

• The focus is on an experiment that supports the chemosynthetic or chemical evolution theory of life's origin.
• The experiment simulated primitive Earth atmosphere and energy sources such as lightning.
• Options given are Miller, Pasteur, Aristotle, and Sanger, all well known names in science history.
• We assume the standard account found in biology textbooks regarding the Miller Urey experiment.

Concept / Approach:
The chemical evolution theory suggests that early Earth had a reducing atmosphere containing gases such as methane, ammonia, hydrogen, and water vapour. Energy from lightning and ultraviolet radiation could drive reactions among these gases to produce simple organic molecules like amino acids. In 1953, Stanley L. Miller, working under the guidance of Harold C. Urey, designed an apparatus that circulated a mixture of such gases and applied electrical sparks as an energy source. After running the experiment, he found several organic molecules in the resulting liquid, including amino acids. This demonstrated that organic compounds necessary for life could form spontaneously from inorganic components under plausible early Earth conditions.

Step-by-Step Solution:
1. Recall that the experiment that tested chemical evolution used a closed glass apparatus representing the early atmosphere and ocean.2. A mixture of gases, commonly methane, ammonia, hydrogen, and water vapour, was circulated through the apparatus.3. Electrical sparks were supplied to simulate lightning, providing energy for chemical reactions.4. After several days, the contents were analyzed and found to contain organic compounds, including amino acids.5. This experiment was performed by Stanley L. Miller, and it strongly supported the idea that simple chemical processes could produce building blocks of life.6. Therefore, the correct answer among the options is Miller.

Verification / Alternative check:
To verify, consider the contributions of the other scientists. Louis Pasteur is famous for his work disproving spontaneous generation and for contributions to microbiology and vaccination, not for simulating early Earth conditions. Aristotle was an ancient philosopher who proposed early ideas about living things but did not perform modern laboratory experiments. Frederick Sanger is known for developing methods for sequencing proteins and DNA. None of these match the description of the origin of life experiment. Only Miller, along with Urey, is associated with the apparatus that synthesized organic molecules from inorganic gases, confirming the chemical evolution idea experimentally.

Why Other Options Are Wrong:
Option B, “Pasteur,” is incorrect because his famous experiments involved sterilized broths and swan neck flasks, which showed that microorganisms arise from existing life rather than spontaneously in nutrient solutions. Option C, “Aristotle,” is wrong since he worked in a time without modern chemistry and did not perform controlled laboratory experiments on chemical evolution. Option D, “Sanger,” is incorrect because his work relates to sequencing biological macromolecules, not simulating prebiotic conditions. None of these scientists carried out the specific experiment that produced amino acids from inorganic gases under simulated early Earth conditions.

Common Pitfalls:
Students sometimes confuse Pasteur's work on spontaneous generation with Miller's work on chemical evolution. Pasteur showed that life does not arise from nonliving matter in ordinary modern conditions, while Miller showed that organic molecules can form from inorganic components under special early Earth like conditions. It is important to keep those two ideas separate. Another pitfall is forgetting that Miller worked with Urey, which leads to uncertainty about which name to choose in multiple choice questions. When the options list only a single surname, Miller is the correct one for the origin of life experiment.

Final Answer:
The idea that life could have originated through chemical evolution in a primordial atmosphere was demonstrated in the laboratory by Miller, in the classic Miller Urey experiment.