EfE Bio Hnrs

Evidence for Evolution

Age of the Earth and Fossil Record

• Earth is approximately 4.6 billion years old.
• Early Earth was hot and lacked oxygen; life began after cooling down (1 billion years later).
• The geologic timeline includes multiple Eras; understanding their length and order of life emergence is critical.

Changes in Earth's Biodiversity

• Estimated 1.5 million species identified, categorized into genera and families.
• Biodiversity has evolved; fossils indicate extinct species and transitions to new forms.
• Key transitional fossils include Archaeopteryx (reptile to bird) and Tiktaalik (water to land).
• Fossil evidence is structured in sedimentary rock layers; older fossils are deeper.

Anatomical Evidence

• Comparative Anatomy examines structures among related organisms (Homologous Structures).
• Homologous structures suggest common ancestry; divergent evolution is evidenced by different functions in similar structures.
• Vestigial Structures (e.g., python and whale leg bones) show traits from ancestors.
• Analogous Structures arise from similar environments, reflecting convergent evolution (e.g., bat wings vs. butterfly wings).

Embryological Evidence

• Closely related species exhibit similar embryonic stages, suggesting common ancestry.

Biochemical and Genetic Evidence

• Comparative Biochemistry analyzes amino acid sequences across species; genetics compares DNA sequences.
• Biochemical evidence is regarded as highly reliable for establishing evolutionary relationships.
• Rapid Evolutionary changes are evident in cases like antibiotic and pesticide resistance.