Hay fever could have driven woolly mammoths into extinction.
Hay fever killed the woolly mammoths
Scientists have found plant pollen in the remains of four of the beasts in what is the first evidence of the animals having allergies.
The experts think that plant pollen damaged the mammoths' sense of smell and hindered their ability to mate and reproduce - leading to a decline in birth rates that resulted in the extinction of the species.
Gleb Zilberstein, co-founder of the company Spectrophon and first author of the study, told The Daily Telegraph newspaper: "This was the first study where fragments of immunoglobulins were found in remains tens of thousands of years old.
"In parallel, fragments of proteins of highly allergenic plants and their pollen were found in these remains.
"We found evidence in mammoth samples of allergies and they may have gone extinct because mammoths developed allergies to pollen during the breeding season which stopped them being able to find each other to reproduce."