The marginal value of gold is held up by people who wear it as a status symbol. If the world population were to decrease or if the supply of gold were to increase, the market price would plunge due to the physical burden of carrying the gold on one's body.
As of 2008, 160000 metric tonnes of gold had been extracted. That's 50g per woman. I'd guess that at around 1 kilo per woman, the demand for gold would be very low. Who would want to walk around with paper weight dangling from their neck?