Earth's Co-Evolution

FOR YOUR NOTEBOOK

Students will learn how Earth’s systems (geosphere, atmosphere, hydrosphere, and biosphere) and life have coevolved. They will analyze evidence to construct an argument about how life influences Earth's environment and how Earth's environment, in turn, influences life.

Section 1: Vocabulary

Coevolution – The process where two or more systems influence each other’s development over time.
Oxygenation Event – The period when early photosynthetic organisms released oxygen, dramatically changing Earth's atmosphere.
Mass Extinction – A rapid loss of many species due to environmental changes.
Fossil Record – The preserved remains of ancient life that provide evidence of evolutionary and environmental changes.
Symbiosis – A close relationship between different species that affects their evolution (e.g., plants and pollinators).

Section 2: Evidence for the Coevolution of Earth’s Systems and Life

The Great Oxygenation Event (~2.5 billion years ago)
- Cyanobacteria, a type of bacteria capable of photosynthesis, released large amounts of oxygen (O₂) into the atmosphere.
- This transformed the atmosphere, leading to the formation of the ozone layer, which protects life from harmful UV radiation.
- The increase in oxygen also led to the evolution of more complex life forms.
Plants and Soil Formation
- The first land plants evolved around 470 million years ago, helping to break down rocks and form soil.
- Plants absorbed CO₂ and released oxygen, further shaping the atmosphere.
- The spread of forests led to cooling periods by reducing greenhouse gases.
The Role of Animals in Shaping Ecosystems
- Early marine animals, such as corals, helped build reef systems, which provided habitats for other species.
- Herbivores influenced plant evolution by eating certain species, which led plants to develop defenses like toxins and thorns.
- Pollinators like bees coevolved with flowering plants, leading to greater biodiversity.

2: How Earth Has Shaped Life

Mass Extinctions and Evolutionary Changes
- The Permian Extinction (~252 million years ago) wiped out 90% of species due to volcanic activity and climate changes, leading to new evolutionary paths.
- The Cretaceous Extinction (~66 million years ago) (caused by an asteroid impact) led to the decline of dinosaurs and allowed mammals to dominate.
Climate and Evolution
- The Ice Ages forced species to adapt by developing thicker fur (mammoths) or migrating to warmer areas.
- Warmer climates in the past allowed for the evolution of tropical species, while colder periods led to adaptations like hibernation.
Tectonic Activity and Biodiversity
- Continental drift changed ocean currents and climate patterns, leading to the evolution of unique species on different continents (e.g., marsupials in Australia).
- The rise of mountains (e.g., the Himalayas) created new habitats and influenced rainfall patterns, affecting plant and animal life.