Grade 10 · Evolution and Natural Selection · Natural Selection
Evidence for Evolution
Fossils, anatomy and DNA — three independent lines of evidence.
Learning objectives
- Describe how fossils provide evidence of change over time.
- Interpret similarities in anatomy and DNA.
- Evaluate the strength of different lines of evidence.
NGSS alignment
MS-LS4-2
Apply scientific ideas to construct an explanation for the anatomical similarities and differences among modern organisms and between modern and fossil organisms to infer evolutionary relationships.
HS-LS4-1
Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.
MS-LS4-1
Analyze and interpret data for patterns in the fossil record that document the existence, diversity, extinction, and change of life forms throughout the history of life on Earth.
MYP criteria
- Criterion A — Knowing and Understanding
- Criterion D — Reflecting on the Impacts of Science
ENGAGE
A whale with finger bones
Inside a whale flipper are bones arranged like the bones in your hand, and hidden in its body are the remains of a hip.
Think about it
- Why would a swimming animal have finger-like bones?
- What would you predict about whale ancestors?
EXPLAIN
Three lines of evidence
| Evidence | What it shows | Limitation |
|---|---|---|
| Fossils | Species existed at different times and changed | Record is incomplete; soft tissue rarely preserved |
| Comparative anatomy | Homologous structures suggest shared ancestry | Similar function can evolve independently |
| DNA and proteins | Closer sequences suggest closer relatedness | Requires preserved or living material |
Evidence is strongest when independent lines agree. Fossil order, limb anatomy and DNA comparisons all place whales closest to hoofed mammals.
Thinking like a scientist
A single fossil is a data point. A pattern across many fossils, many species and many genes is a theory.
- Homologous structures — same origin, different function
- Analogous structures — different origin, similar function
- Vestigial structures — reduced remains of features used by ancestors
SOURCES
Where to read more
- Understanding Evolution, University of California Museum of Paleontology https://evolution.berkeley.edu
- Smithsonian Human Origins https://humanorigins.si.edu
Watch
Evolution
Amoeba Sisters · 9 min
Summarises the main lines of evidence for evolution.
Before you watch: Which type of evidence do you find most convincing?
- Name three independent lines of evidence.
- Why is agreement between lines of evidence important?
Interactive simulation · PhET
Natural Selection
Run the model for many generations and record how allele frequencies change.
While you explore
- What evidence in the graph shows change over time?
- How is this similar to reading a fossil sequence?
Key vocabulary
- Fossil
- Preserved remains or traces of an ancient organism.
- Homologous structures
- Body parts with the same basic plan but different uses.
Practice questions
0/2 correct
Level 1 · Criterion A
Homologous structures suggest that two species:
Level 2 · Criterion A
Which is the main limitation of fossil evidence?
MYP criterion tasks
Level 3 · Criterion D
Evaluate why scientists treat evolution as a well-supported theory rather than a single hypothesis.
Reflect & track
Your learning log
Saved privately in this browser — no account needed.
How confident do you feel?