Mayans were drinking some type of chocolate as early as 600 BC, according to a new study conducted by researchers at the University of Texas and major US confectioner Hershey Foods.

The study pushes back the time that people have used drinking chocolate by about 1,000 years; as scientists previously estimated the date at between 460 AD and 480 AD.

Terry Powis, a post-doctoral research fellow in archaeology at the University of Texas, explained that he discovered traces of cacao inside three spouted ceramic vessels unearthed at Colha, a Mayan archaeological site in Belize twenty years ago. Using carbon-14 dating, archaeologists were able to establish that the vessels were made between 600 BC and 250 AD.

Powis sent 5-grams residue samples from the inside of the vessels to W. Jeffrey Hurst, a senior staff analyst at Hershey, who used high-performance liquid chromatography (HPLC) and mass spectrometry to establish the presence of theobromine, a compound found in the cacao plant.

Hurst, who details the tests in the journal Nature, said of the chocolate: "I'd conjecture it would not be to our liking. It was probably roasted and ground-up cocoa mixed with some kind of water and spices; definitely not what we're used to today."