HS-LS4-1: Evidence for Common Ancestry
Also called NGSS HS-LS4-1 · Topic: Natural Selection and Evolution · Life Science
The Official Wording
Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.
Clarification statement: Emphasis is on a conceptual understanding of the role each line of evidence has relating to common ancestry and biological evolution. Examples of evidence could include similarities in DNA sequences, anatomical structures, and order of appearance of structures in embryological development.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-LS4-1 Means in Plain English
Students explain, in writing, talks or visuals, how several independent kinds of evidence point to the same conclusion: living things share common ancestors and have changed over time. The evidence includes DNA and protein comparisons, shared body structures, embryo development and the fossil record.
The goal is understanding what each line of evidence adds, not memorizing examples. It builds on MS-LS4-1, MS-LS4-2 and MS-LS4-3 and sets up HS-LS4-2 and HS-LS4-4, which explain how evolution happens through natural selection.
HS-LS4-1 I Can Statements
- I can name several kinds of evidence for common ancestry.
- I can explain what DNA comparisons reveal about relatedness.
- I can show how fossils and anatomy support the same conclusion.
HS-LS4-1 Worked Example
An evidence board on where whales came from, built by small groups that each research one line of evidence.
Did whales evolve from land mammals, and do different kinds of evidence agree?
Set It Up: Printed fossil skeleton drawings, a modern whale skeleton diagram, a short DNA comparison summary and dolphin embryo photos, one set per group.
- Fossil group: arrange skeletons of Pakicetus and Ambulocetus by age and compare their legs with a modern whale's.Four legs, then shorter legs, then no hind legs
- Anatomy group: find the small pelvis inside a modern whale skeleton.A leftover pelvis with no legs attached
- DNA group: read which living mammals share the most DNA with whales.Closest living relatives: hippopotamuses
- Embryo group: compare dolphin embryos at early and later stages.Hind limb buds appear, then disappear
- Pin all four findings on one board and look for agreement.Every line points to a land-mammal origin
Fossils, anatomy, DNA and embryos all pointed independently to whales descending from four-legged land mammals related to hippos.
Why it works: When separate kinds of evidence, gathered in different ways, support the same family tree, that agreement makes shared descent a strong scientific explanation.
Common Mistakes with HS-LS4-1
Thinking humans came from chimpanzees
“If we evolved from monkeys, why are there still monkeys?”
Try this: Humans and chimpanzees share a common ancestor that lived millions of years ago, and both lines have changed since they split.
Similar looks mean close kin
“Sharks and dolphins are close relatives because they look alike”
Try this: Look at bones and DNA, not body shape: dolphins have mammal skeletons and DNA, and their shape evolved separately for swimming.
Leaning on one piece of evidence
“The fossil record has gaps, so evolution is unproven”
Try this: Show how DNA, anatomy and embryos fill in the story independently, so the conclusion does not rest on fossils alone.
Where HS-LS4-1 Fits
Practice HS-LS4-1
Quick Check
- Why do whales have small hip bones?
- What does it mean when two species have very similar DNA?
- Why is it convincing when fossils and DNA tell the same story?