What is population explosion and what are its causes?

A population explosion occurs when a species has a birth (or hatching) rate that is significantly greater than its death rate.

This can happen among nonhuman animals, usually as a result of a period of weather conducive to growth of food and to reproduction.

Among people, the population explosion of the last hundred years or so has been the result of better sanitation and medical care, improvements in food production, storage and distribution and reductions in the cost of food. The development of antibiotics, pesticides, synthetic fertilizers, and the application of mechanization to the farm have all contributed to this.