More boys are born. Women live longer. For eight billion people those two forces cancel out almost exactly, and the planet ends up split 50.25 to 49.75.

Almost exactly is not exactly. Tonight the whole map gets a say. Country after country steps up, adds its men to one score and its women to the other, and the verdict refuses to sit still.

The lead changes hands 40 times.

For most of the ride the gap stays within a few million people and keeps flipping. Then Saudi Arabia hands the men their first real lead, seven million clear, and the map starts pushing back.

The two biggest countries on Earth come last.

Men or women? Call it before the map fills up, and tell me in the comments whether the world agreed with you.