Notes on Natural Selection Lecture

Introduction to Natural Selection

• Previous videos were artificial: creatures had preset replication and death chances.
• Natural selection involves interactions between creature traits and the environment.
• Aim: Create a real evolving system by introducing a simple environment and traits for blob creatures.

Environment Setup

• Creatures live on a plane where food appears each morning.
• Blobs emerge from the edge to find food.
• Rules
  • If a blob fails to find food before running out of energy, it dies.
  • If a blob finds one piece of food and returns home, it survives.
  • If a blob finds two pieces and returns, it replicates.

Observations and Initial Results

• Population starts below carrying capacity, increases, then stabilizes.
• Competition for food begins around a population size of 95.
• Variations and mutations start to show natural selection.

Introducing Mutations: Speed Trait

• Speed affects food gathering efficiency but costs more energy.
• Faster creatures use more energy and may not forage as widely.
• Natural selection favors faster speeds, leading to higher average speed over time.
• Populations evolve; individuals do not.
• Increased speed leads to more competition and a lower population.

Additional Traits: Size and Sense

• Size
  • Allows creatures to eat others if they are 20% larger.
  • Energy cost scales with the cube of size.
  • High risk and high reward. Requires speed to effectively benefit.
• Sense
  • Sensing distance affects awareness of food and other creatures.
  • Each movement costs energy proportional to sensing trait.

Simulating All Three Traits

• 3D graph tracks speed, size, and sense mutations.
• Average speed differed from single trait mutation results.
• Sense trait did not become dominant as initially anticipated.
• Natural selection operates independently of human assumptions.

Environmental Changes: Food Availability

• Reduced food changes population dynamics and traits.
• Initial population couldn’t sustain itself with less food.
• Gradual food reduction allows population adjustment.
• New low-food environment favors high sense and high speed.

Lessons Learned

• Environment significantly impacts evolutionary outcomes.
• Evolution is not a progression to more complex forms, but adaptation to the environment.
• Future videos will explore more complex traits in natural selection.

Recap

• Through simulations, important principles of natural selection were observed.
• Future content will address more complex and unexpected traits influenced by natural selection.