HS-ESS2-7: How Life and Earth Shaped Each Other
Also called NGSS HS-ESS2-7 · Topic: Earth's Systems · Earth and Space Science
The Official Wording
Construct an argument based on evidence about the simultaneous coevolution of Earth’s systems and life on Earth.
Clarification statement: Emphasis is on the dynamic causes, effects, and feedbacks between the biosphere and Earth’s other systems, whereby geoscience factors control the evolution of life, which in turn continuously alters Earth’s surface. Examples include how photosynthetic life altered the atmosphere through the production of oxygen, which in turn increased weathering rates and allowed for the evolution of animal life; how microbial life on land increased the formation of soil, which in turn allowed for the evolution of land plants; or how the evolution of corals created reefs that altered patterns of erosion and deposition along coastlines and provided habitats for the evolution of new life forms.
Assessment boundary: Assessment does not include a comprehensive understanding of the mechanisms of how the biosphere interacts with all of Earth’s other systems.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-ESS2-7 Means in Plain English
Students argue from evidence that life and Earth's other systems have changed together, each shaping the other. Ocean microbes that photosynthesized filled the air with oxygen, which rusted iron out of seawater and later made animal life possible, while rocks and climate steered which life could thrive.
Students build an argument from a few clear examples, not a full account of every link between life and Earth. It builds on evolution evidence (HS-LS4-1) and the carbon cycle (HS-ESS2-6), and it frames humans as today's newest planet-changing life.
HS-ESS2-7 I Can Statements
- I can give an example of life changing Earth's atmosphere.
- I can give an example of Earth's changes steering evolution.
- I can use rock evidence to support a claim about coevolution.
HS-ESS2-7 Worked Example
A rust test that models how early oxygen changed the oceans, read alongside real rock evidence.
What happened to the iron dissolved in early oceans once photosynthesizing microbes began releasing oxygen?
Set It Up: Steel wool in two test tubes, one with tap water open to the air and one with boiled water sealed under a layer of oil, plus photos of banded iron formation and stromatolites.
- Leave both tubes for three days and check them each day.Open tube: orange rust, sealed tube: little change
- Link the result to early oceans, which held dissolved iron and almost no oxygen.Oxygen + iron → iron oxide, which settles out
- Examine banded iron formation, layers of iron oxide laid down mostly between about 2.5 and 1.8 billion years ago.Red iron bands record rising oxygen
- Examine stromatolites, layered mounds built by photosynthesizing microbes.The oxygen source, found in rocks over 3 billion years old
- Build the argument: microbes changed ocean and air chemistry, and the oxygen later allowed animals to evolve.Claim, evidence, reasoning
Iron rusted only where oxygen reached it, matching the rock record of iron settling out once microbes began releasing oxygen.
Why it works: Photosynthesis released oxygen that reacted with dissolved iron, changing ocean and air chemistry, and that oxygen-rich world opened the way for new kinds of life.
Common Mistakes with HS-ESS2-7
Thinking life only adapts to Earth
“Earth sets the conditions and living things just adjust.”
Try this: The influence runs both ways. Microbes rebuilt the atmosphere, plant roots created soil, and coral reefs reshaped coastlines, changing conditions for later life.
Assuming the air always had oxygen
“Early Earth's air was like today's, just younger.”
Try this: Early air held almost no free oxygen. It built up only after photosynthesizing microbes released it for hundreds of millions of years.
Giving a claim without a mechanism
“Life changed Earth because there are fossils.”
Try this: Name the process that links the two, such as oxygen from photosynthesis reacting with iron, and show the rock evidence for it.
Where HS-ESS2-7 Fits
Practice HS-ESS2-7
Quick Check
- What made banded iron formations?
- Give one way life has changed Earth's surface.
- Why could large animals not evolve on very early Earth?