When English colonial invaders occupied the island of Barbados in 1627, they were surprised to find a herd of what they believed to be wild European pigs. How the animals got there was a huge mystery, as there was no reason to bring them all the way from Europe.

Researchers have now discovered that the pigs seen back in the 17th century weren't pigs at all. They were peccaries, a pig-like but genetically different mammal, which is commonly found in Central and South America.

As reported in PLOS ONE, Christina Giovas, an archaeologist from Simon Fraser University in Canada discovered the jaw bone of a peccary while working on a project on the early introduction of animals to the Caribbean.

"I didn't give it much notice at the time, but simply collected it along with other bones," Giovas said in a statement. "It was completely unexpected and I honestly thought I must have made a mistake with the species identification."

Giovas and collaborators George Kamenov and John Krigbaum of the University of Florida wanted to know how old this jaw bone was as it would give them an idea of when the animals were introduced to the island. They used radiocarbon dating to establish age and measured levels of strontium isotopes in the bone to discover if the animal was local or not.

They discovered that the peccary lived between 1645 and 1670 and was indeed local to Barbados. This explains the “wild pigs” depicted in early maps of the island, including the famous 1657 ones. However, this starts a new mystery. Who brought these animals to the island? The team believes that it was Europeans.

"Checking historical and archaeological records, we determined the most likely source of peccary introduction was from Spanish or Portuguese ships passing the island in the 16th century – and most likely left as a source of meat for future visiting sailors," Giovas said.

The findings show just how quickly the European invasion of the Americas altered the environment of the Caribbean. It also changes some of the accepted colonial histories of the island, which was first settled by Arawaks, an Amerindian civilization, around 1620 BCE.