Optimal Human Population for Earth Under the Four Universal Laws: A Bio-Systemic Engineering Approach

As of 2026, the human population of approximately 8.1 billion exerts a pressure on the Earth’s biosphere that is mathematically unsustainable. This paper defines an “Optimal Set Point” for the human species by applying four universal laws: Balance, Feedback, Systemic Perfection, and Harmony. By solving for the most restrictive resource bottleneck—arable land and biodiversity preservation—this study concludes that a global population of \textbf{2.5 billion} is the threshold for a defect-free, long-term civilization. A 100-year transition roadmap and continental distribution framework are provided.