Evidence of Change
Middle School
Definition
Observations that show how species and the Earth have changed over time, such as fossils, rock layers, and similarities in anatomy and DNA. This evidence supports scientific explanations like evolution.
Worked examples
Fossil of Archaeopteryx shows both bird features (feathers, wings) and reptile features (teeth, bony tail)
This transitional fossil is evidence that birds evolved from reptilian ancestors.
Human and chimpanzee DNA are about 98% identical
High DNA similarity is evidence that humans and chimps share a recent common ancestor.
Rock layers in the Grand Canyon show older fossils at the bottom and younger fossils at the top
The sequence of fossils in rock layers is evidence that life forms changed over millions of years.
Common mistakes
- Fossils are the only evidence for evolution → Multiple lines of evidence support evolution: fossils, DNA, anatomy, embryology, and biogeography Evidence of change comes from many independent sources that all point to the same conclusion.
- Similar structures in different species happened by coincidence → Similar structures (like limb bones in mammals) are evidence of common ancestry Homologous structures share the same underlying pattern because organisms inherited them from a shared ancestor.
Where you'll use it next
You'll apply evidence of change when studying natural selection, speciation, and evolutionary biology. It also connects to genetics, paleontology, and understanding how scientists build explanations from multiple data sources.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026