Lecture on the History and Evolution of Earth and Life

Formation of the Solar System and Earth

Milky Way Collision: Over 4.5 billion years ago, the Milky Way collided with a dwarf galaxy, catalyzing star formation.
Solar System Formation: Material circulation within the solar system; water evaporation led to dry material formation and zonal particle distribution.
Planetesimals and Planet Formation:
- High particle density regions formed around the Sun.
- Frequent collisions led to planetesimals merging and growing into planets like Earth.

Early Earth collided with a Mars-sized planet, forming debris that became the Moon.

Bombardment by water-rich planetesimals led to Earth being covered by an ocean-atmosphere system.
High salinity and metal-laden seas initially made oceans toxic.
Plate tectonics began: Oceanic plates subducting under continental plates.
Weathering neutralized the ultra-acidic ocean, making it habitable over time.

First Cells: Formed around 4.2 billion years ago, primitive life emerged in geyser caves.
Mantle Convection: Dramatic changes caused plate movement and formation of habitable environments.
Material Circulation: Necessary for life; continuous flow of electrons was key to life’s energy needs.
Evolution: Mutations allowed life to use sunlight and develop metabolism, leading to more complex forms.

Cyanobacteria: Produced oxygen, changing the atmosphere and turning ocean blue by reducing iron content.
Mantle Overturn: Pushed land masses upward, creating shallow marine environments conducive to cyanobacteria growth.
Surviving Snowball Earth: Life adapted and evolved during global glaciation events.
Endosymbiosis: Prokaryotes evolved into more complex life by forming symbiotic relationships, creating mitochondria and chloroplasts.

Supercontinent Cycles: Nuna and Rodinia supported and spurred evolution.
Atmospheric Changes: Large landmasses added oxygen to the atmosphere, aiding evolution.
Evolution Milestones:
- Cambrian explosion: Rapid diversification of life.
- Evolution from single-celled to multicellular organisms.

Algae to Land: First life forms to transition to land.
Vertebrate Evolution: Fish evolved into amphibians, reptiles, and ultimately mammals and humans.
Dinosaur Dominance: Dinosaurs thrived before another major extinction event.

Primates and Hominins: Stem evolution in Africa led to the emergence of Hominins, our ancestors.
Genetic Regions: HARs (Human Accelerated Regions) differentiated humans from other animals.
Dispersal and Civilization: Human ancestors dispersed globally, created agriculture, and complex civilizations emerged.

Fossil Fuels: Rapid depletion and environmental contamination.
Technological Advances: Space exploration and development of AI.
Supercontinent Amasia: Predicted to alter atmospheric CO2 levels and environmental conditions.
End of Plate Tectonics: Cooling planet will ultimately cease plate tectonics, leading to severe environmental changes and extinction.
Final Extinction: Earth will become uninhabitable due to solar expansion and cosmic events.
Legacy of Life: Life will spread beyond Earth, potentially as artificial forms.