Domesticated chickens, it turns out, could be a signpost for future archaeologists that screams, “Humans were here!” The total weight of the species Gallus gallus domesticus not only exceeds the weight of all wild birds combined, domesticated chickens also carry distinctive signs of industrialized farming in their very bones.

“They’re an example, really, of how we’ve changed the biosphere to suit our needs as humans,” said Carys Bennett, the lead author of a new study published today (Dec. 11) in the journal Royal Society Open Science that argues that chicken-bone fossils may mark a new geological epoch, the Anthropocene.