Overview

This topic explores the scientific understanding of how life originated on Earth and the processes that led to the diversity of species through evolution. It includes key theories, mechanisms of change, and evidence supporting the evolutionary history of life.

Key Concepts and Theories

• Abiogenesis: The theory that life originated from non-living matter under early Earth conditions. Experiments like the Miller-Urey experiment simulated conditions of early Earth and showed that amino acids could form spontaneously.
• Primordial Soup Hypothesis: Proposes that life began in a "soup" of organic molecules, possibly in oceans or near hydrothermal vents, where simple compounds became more complex over time.
• RNA World Hypothesis: Suggests that RNA molecules were the first self-replicating systems, acting as both genetic material and catalysts (ribozymes).
• Natural Selection: A process proposed by Charles Darwin in which organisms better adapted to their environment tend to survive and reproduce. This is the primary mechanism of evolution.
• Mutation: Random changes in DNA that introduce new genetic variation, which can be acted upon by natural selection.
• Speciation: The formation of new and distinct species through evolutionary processes such as geographic isolation and genetic divergence.
• Fossil Record: Provides chronological evidence of past life and evolutionary transitions, such as the progression from fish to amphibians.
• Homologous Structures: Anatomical features shared by different species due to common ancestry (e.g., the limb bones of mammals).
• Vestigial Structures: Body parts that have lost their original function through evolution (e.g., human appendix).
• Common Ancestry: All living organisms are believed to have descended from a common ancestral cell, sometimes referred to as LUCA (Last Universal Common Ancestor).

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