In the late 1800s, the Rio de Janeiro zoo was struggling financially. Its founder, Baron João Batista Viana Drummond, needed a creative way to attract more visitors. His solution, launched in 1892, was a raffle tied to the zoo's animals.

Upon entry, each visitor received a ticket with an animal printed on it. At the end of the day, the Baron would reveal a randomly chosen animal, and the person holding the matching ticket won a cash prize. The idea was a massive success, and soon, people were buying tickets outside the zoo, betting on which animal would be chosen. This was the birth of jogo do bicho, or "the animal game."

Though it was quickly declared illegal, the game's popularity never faded. It evolved into an independent lottery system, a cornerstone of Brazil's informal economy and culture.

The game is built around 25 animals, each representing a group of four consecutive numbers, from 00 to 99. The number 00 is associated with the last group. The ostrich starts things off with group 1, covering numbers 01 to 04, and the cow finishes with group 25, covering numbers 97 to 00.

Players place their bets with a bookie, known as a bicheiro. You can bet on an animal (a group of four numbers), a specific two-digit number (dezena), a three-digit number (centena), or a four-digit number (milhar). The more specific the bet, the higher the payout.

There is no single, official draw for the game. Instead, the results are typically based on the winning numbers from Brazil's official state and federal lotteries. The operators simply use the last two, three, or four digits of the official lottery's winning number as the result for the animal game.

This creates a clever loophole. The bicheiros aren't running their own lottery; they're just organizing bets based on the outcome of a legal one. Draws happen frequently, often multiple times a day, corresponding to the various state lottery drawings.

The game's organization is hierarchical, resembling a crime syndicate with local bookies reporting up to regional bosses. This structure has allowed it to survive for over a century, weaving itself into the fabric of Brazilian life despite its illegal status.