Historical Human Population Growth

• Modern humans emerged 200,000 years ago with unique abilities: tool-making, storytelling, abstract thinking, planning, large group cooperation
• Slow early growth: 150,000 years to reach 2 million population
• Agricultural revolution: biggest change in human history, real population growth began
• Additional 10,000 years to reach 300 million
• Industrial revolution (1800): 1 billion humans
  • Population doubled in 120 years, then again in 50 years
• Current population: ~8 billion
• Total humans ever born: 117 billion (109 billion died)
• 7% of all humans ever lived are alive now
• Current birth rate: 270 babies per minute

Population Projections and Peak

• UN estimates population peak around 2100: 125 million births per year
• Growing living standards causing birth rate collapse
• Future population depends on species survival duration

Human Extinction Risks and Solutions

• Dual nature of human inventions: destructive and protective capabilities
• Examples of risks/solutions:
  • Planet killer asteroids (can redirect) vs nuclear weapons
  • Antibiotics vs global disease spread
  • Industrial living standards vs atmospheric changes
• Human ingenuity impact on species lifespan uncertain

Future Population Scenarios

Scenario 1: Humans Never Leave Earth

• Mammalian species average lifespan: 1 million years (some up to 10 million)
• Homo erectus survived 1.9 million years
• Conservative estimate: 1 million year human survival (800,000 years remaining)
• 125 million births/year = 100 trillion future humans
• 850x greater than all humans who ever lived
• Current population: 0.008% of all humans who will ever live
• Optimistic mammalian survival match: 1.2 quadrillion future people
• Earth habitable for 500 million more years as sun brightens

Scenario 2: Humans Leave Earth

• Solar system expansion potential within few hundred years
• Life requirements: surface, resources, energy
• Sun provides billions of years of energy
• Asteroid and Kuiper belt materials sustain many times current population
• Artificial worlds and habitats construction
• Different society types possible with abundant resources
• Quadrillions of future people possible
• Benefits: billions of doctors, problem solvers, developers
• Extinction resistance: requires solar system-wide catastrophe
• Safe from most threats except nearby supernovae, gamma-ray bursts
• Potential billions of years survival
• Evolution/genetic engineering may create multiple species

Scenario 3: People Leave Solar System

• 100 billion star colonization over 10 billion years
• 100 million births per year per system
• Result: 100 octillion future lives (1 with 29 zeros)
• Andromeda-Milky Way merger adds trillion more stars
• Red dwarf stars active for trillion years
• Advanced civilizations might use black hole energy
• Galaxy group expansion possible
• Energy-based calculation: treatrillion potential lives (million trillion trillion trillion)

Present Moment Significance

• Current era: high point in human history with incredible possibilities
• Technological, environmental, societal opportunities
• Present actions affect all future unborn people
• Conservative estimates show unborn far outnumber living
• Unborn people most disenfranchised group
• Future person born in 1000+ years depends on today's decisions
• Perspective shift: living at beginning of human story, not end
• Potential to build wonderful world for current and future generations