Everybody poos, but not all poos are alike. An ancient piece of dehydrated human dung contains the bones, scales and a fang of a venomous snake — an indication that the reptile might have been eaten whole, likely as part of a ritual event.

Ancient peoples of North America routinely ate snakes, even poisonous ones, usually after they removed the scales and head. But when Elanor Sonderman at Texas A&M University in College Station and her colleagues analysed a 1,500-year-old sample of human dung found in Texas, they identified 22 snake bones, 48 snake scales and a 1-centimetre-long snake fang. This suggests that the reptile, probably a western diamondback rattlesnake (Crotalus atrox), was eaten whole and unskinned.

Many peoples, including Indigenous groups in the southwestern United States, worshipped snakes, leading the team to propose that the animal was consumed during a ceremony or ritual. The faeces also contain the remains of a small rodent, consumed whole and apparently raw. But whether the rodent had been the human’s or the snake’s meal is unclear, the researchers say.