Tracing Human Migration from Mitochondrial Eve

Introduction

• Mankind has existed for millions of years, but significant attention arose when early ancestors began migrating from Africa.
• Present-day humans (7.5 billion) are descendants of a single woman known as Mitochondrial Eve, who lived around 200,000 years ago in Eastern Africa.
• Purpose of this lecture: to follow the migration paths of Mitochondrial Eve's descendants.

Mitochondrial Eve's Origin

• Location: East Africa
• Key Features:
  • Lake Victoria: 59,947 square meters, significantly larger than major cities (e.g., 38 times larger than London).
  • Serengeti Plains: Covers approximately 30,000 km², a vital ecological zone.
  • Mount Kilimanjaro: Highest mountain in Africa, dormant volcano with glaciers expected to disappear between 2025-2035.

Hunter-Gatherer Lifestyle

• Mitochondrial Eve's descendants lived as hunter-gatherers in a dynamic environment affected by climate change.
• Prey migration led to shifts in human habitats and lifestyles, which are represented by migration routes in the presentation.

Genetic Insights

• Mitochondrial DNA (mtDNA) is inherited solely through females, allowing scientists to trace lineage.
• Mitochondrial DNA Transmission:
  • Men possess mtDNA, but it is not passed to offspring.
  • During fertilization, only the head of the sperm enters the egg, leaving the tail (where mtDNA resides) behind.

Research Findings

• Initial studies dating back to 1985 provided evidence supporting the African origin of all modern humans through mtDNA analysis.
• By 1987, it was concluded that all current humans descended from a single African population existing 140,000 - 200,000 years ago.

Migration Patterns

• 60,000 - 80,000 Years Ago: Expansion of L2 and L3 mtDNA types in Africa.
• 50,000 - 60,000 Years Ago: L3 type migrated to Southwest Asia, leading to M and N types that further spread globally.
• Ice Age Navigation:
  • Early humans crossed over water bodies using rafts (Sundaland) to reach Australia (50,000 - 40,000 years ago).

Migration to Other Continents

• Types of Migration:
  • I, U, H, V types migrated to Europe, introducing new genetic lineages.
  • Types A, B, C, D, and X spread across East Asia and North America, with routes taking advantage of land connections during low sea levels.

The Last Glacial Maximum (LGM)

• Occurred between 33,000 and 25,600 years ago, characterized by extreme cold and lower sea levels.
• Migration across the Bering Sea and southward into the Americas took place around 20,000 years ago.

Post-Ice Age Migration

• Post-Ice Age Warming: Types A, B, C, and D moved into South America via an ice-free corridor.
• Younger Dryas Period (12,900 - 11,700 years ago): Significant climate fluctuations affecting migrations.
• Later migrations included movement to Polynesia and Madagascar.

Summary of Migration Types and Current Distribution

• Key Types:
  • L: Original type in Africa.
  • N: Spread to Western Asia and beyond.
  • M: Found in Arabian Peninsula, India, East Asia, Australia.
  • D: Found in Alaska and South America.
  • A, B, C: Wide distribution across Asia, America, and islands.
• Map displays modern distribution of mitochondrial DNA types.

Conclusion

• Through mapping the journey of Mitochondrial Eve and her descendants, we gain valuable insights into human history and migration.
• The journey spans 200,000 years and illustrates the complex pathways our ancestors took to populate the globe.

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