6.3.4 Evidence for Evolution

The theory of evolution by natural selection, first proposed by Charles Darwin, is now widely accepted due to substantial supporting evidence.

Key Evidence for Evolution:

1. Fossils:

• Fossils are the preserved remains or traces of organisms that lived millions of years ago, found in layers of rock.
• They provide a historical record of life on Earth, showing how species have gradually changed over time.
• Fossil records demonstrate the existence of species that are now extinct and reveal transitional forms that illustrate the gradual process of evolution.

2. Antibiotic Resistance in Bacteria:

• Antibiotic resistance occurs when bacteria evolve in response to the selective pressure exerted by the use of antibiotics.
• Mutations in bacterial DNA can lead to resistance, allowing those bacteria to survive and reproduce in the presence of antibiotics.
• Over time, these resistant strains become more common, providing a real-time example of natural selection and evolutionary change in response to environmental pressures.