Origins of Life: A Journey to the Beginnings

Introduction

• Journey to explore the origins of life, involving both geographical travel and time travel.
• Aim: To uncover the first living creatures and understand how life evolved to its present complexity.
• Use of modern technology to bring ancient creatures to life (after half a billion years).
• Exploration starts in Britain, specifically Charnwood Forest.

Mystery of Life's Origin

• Life's history is like a branching tree, with all current species linked to common ancestors.
• Five kingdoms of life: Bacteria, Protists, Fungi, Plants, Animals.

Charnwood Forest Discovery

• Ancient rocks (~600 million years old) initially thought incapable of containing fossils.
• A schoolboy discovered a fossil named Charnia, challenging previous scientific beliefs.
• Charnia: Marine organism, lived in darkness at ocean bottom. Distinction between plant and animal still unclear.

Timeline of Life on Earth

• Human existence: ~2 million years.
• Dinosaurs extinct: 65 million years ago.
• Charnia: 560 million years ago.
• First single-celled organisms: ~3.5 billion years ago.

Early Earth Conditions

• Earth had 6-hour long days, faster rotation.
• Volcanic activity, hostile environments, but deep-sea life began.
• Theory: Chemicals from underwater volcanic vents created conditions for first cells.
• Early cells: Photosynthesizing bacteria (e.g., stromatolites in Western Australia).

The Great Glaciation

• Evidence of global glaciation just before complex life appeared.
• Known as “Snowball Earth,” with ice from pole to pole.
• Majority of early bacterial colonies crushed, but life survived via extremophiles.
• Microbial life during glaciation: Adaptable extremophiles found in glaciers like Columbia Icefield.

Post-Glaciation Life Surge

• Melting of glaciation led to volcanic eruptions and CO2 release, warming Earth.
• Nutrient-rich meltwater fueled microbial growth, increasing oxygen levels.
• Oxygen surge enabled complex multicellular life.

Evolution of Multicellular Organisms

• Sponge example: One of the simplest multicellular organisms, surviving ~600 million years.
• Sponge cells bound by collagen: Key to multicellularity requires oxygen.
• Australian research: Sponge cells as a model for early multicellular organisms.
• Role of collagen and oxygen in the evolution of multicellular life.

Mistaken Point Fossils

• Canada’s Mistaken Point contains some of the first animal fossils (~565 million years ago).
• Fossils show organized shapes, including fractal or modular bodies.
• Fractal organisms: Simple, efficient body plan but incapable of evolving complex features like brains or teeth.

Evolutionary Transition to Mobility

• Ediacra Hills in South Australia show first mobile animals (~550 million years ago).
• Evidence: Dickinsonia moved slowly across seafloor; Kimberella had a feeding proboscis, moved by muscular foot.
• Bilateral symmetry developed: Head, tail, segmented bodies enabling directed movement.

Sexual Reproduction and Evolution

• Evidence of sexual reproduction in Funisia: Developed about 550 million years ago.
• Significance: Increased genetic variation and evolutionary speed.
• Modern comparison: Coral’s synchronized reproductive event on the Great Barrier Reef.

Complexity and Predation

• Fossil embryos from South China show early development of guts and mouths (~530 million years ago).
• Marquailia: Early predator with ringed teeth, advanced digestion.
• Evolutionary explosion: Rise of predators in oceans, leading to a complex food web.

Conclusion and Future Exploration

• Next steps: Explore evolution of skeletons and shells, development of complex eyes, adaptation to land and air.
• Continual journey to understand how life conquered various environments on Earth.