Overview

• Dean Spears and Michael Geruso show that nearly every country now records a fertility rate below the two-child threshold needed for population stability.
• Recent demographic data confirm that no nation has managed to reverse a sustained decline once its birth rate falls below replacement level.
• Models in After the Spike project humanity will reach roughly ten billion around the 2070s or 2080s before entering a long-term decline.
• Prospective parents increasingly cite rising opportunity costs—loss of leisure and personal pursuits—as the primary deterrent to having more children.
• Historical pro-natalist measures have only delivered temporary fertility bumps, emphasizing the difficulty of designing enduring population policies.