# The Theory of Evolution

The theory of evolution, most comprehensively developed by Charles Darwin, explains how life on Earth changes over time. Here are its core ideas:

## Key Principles

**Natural Selection** – Organisms with traits better suited to their environment are more likely to survive and reproduce, passing those traits to offspring. Over time, this shifts the characteristics of a population.

**Common Descent** – All living organisms share ancestors. Life branches out over time like a tree, with species diverging from common predecessors.

**Variation** – Individuals within a population differ in their traits, due to genetic mutations, recombination, and other sources of variation.

**Inheritance** – Traits are passed from parents to offspring through genes.

**Deep Time** – These processes operate over vast timescales (millions to billions of years), allowing small changes to accumulate into large differences.

## Additional Mechanisms

Beyond natural selection, evolution also involves:
- **Genetic drift** (random changes in gene frequency)
- **Sexual selection** (traits favored by mate choice)
- **Gene flow** (movement of genes between populations)

## What It Explains

The theory accounts for the diversity of life, the fossil record, anatomical similarities between species, shared DNA sequences, and observable changes in populations today (such as antibiotic resistance in bacteria).

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