The Heat Within: An Ice Age Legacy

Surviving the Ice Age wasn’t guaranteed. Extreme cold, long winters, and scarce food

pushed early human populations to the edge of survival. But humans had one critical advantage.

Their bodies changed how fat worked. Most animals store fat for later. Humans evolved brown

fat - fat that burns energy to produce heat. Instead of just storing calories,

humans could turn fat into warmth. That made freezing climates survivable. Humans moved north,

crossed frozen land bridges, and settled new continents. Even today,

human metabolism still carries traces of this Ice Age adaptation. What do you

think the world would look like today if humans never learned to turn fat into