When aliens or our distant progeny sift through layers of sediment 500,000 years from now to decode the Earth's past, they will find unusual evidence of the abrupt change that upended life half-a-million years earlier: chicken bones.
That is the conclusion of scientists whose findings are offered as proof that rapid expansion of human appetites and activity so radically altered natural systems as to tip Earth into a new geological epoch called the Anthropocene, or the "era of humans".
There will be other telltale clues in mud and rocks of a planetary-scale rupture around the mid-20th century: the sudden rise of CO2, methane and other greenhouse gases; radioactive detritus from nuclear bomb tests; omnipresent microplastics; and the spread of invasive species.
But chicken bones could be among the most revealing findings, and tell the story in more ways than one.
To begin with, they are a human invention.
"The modern meat chicken is unrecognizable compared to its ancestors or wild counterparts," said Carys Bennett, a geologist and lead author of a 2017 study in Royal Society Open Science laying out the evidence for the animal as a "marker species" of the Anthropocene.
"Body size, the shape of the skeleton, bone chemistry and genetics are all distinct."
Their very existence, in other words, is evidence of humanity's capacity to hack nature and intervene in natural processes.
'Clear signal'
The modern broiler chicken's origins are in the jungles of Southeast Asia, where its forebear, the red junglefowl (Gallus gallus), was first domesticated some 8,000 years ago.