Scientists estimate there are at least 1.5 million ants on the planet for every human being. Over 12,000 species of ants are known to exist, on every continent except Antarctica. Most live in tropical regions. A single acre of Amazon rainforest may house 3.5 million ants.

Ants are very strong, they are capable of carrying objects 50 times their body weight with their mandibles.

Ants evolved some during the early Cretaceous period. Most fossil evidence of insects is found in lumps of ancient amber, or fossilized plant resin. The oldest known ant fossil (a primitive and now extinct ant species named "Sphercomyrma freyi") was found in Cliffwood Beach, NJ.

More Info: insects.about.com