The world might be warming, but people are getting colder.
Since the 1800s, the average human body temperature has dropped by just over 0.5C, a new study has found.
Researchers in the US looked at temperature data dating back to the early 1800s, and found since then the average reading has dropped from 37C to 36.6C.
American men born in the 2000s average 0.58C cooler than their early 1800s counterparts, while women nowadays are 0.32C cooler.
"We as human beings have evolved over time - physiologically changed," study author Julie Parsonnet of Stanford University told Live Science.
"We've changed from who we were in the 19th century, and who we were in the 1960s, to a different human today that's colder."
But why? The study notes while there are "many factors" which could influence it, the obvious difference between now and then is medicine.
"Change in the population-level of inflammation seems the most plausible explanation."
Diseases like malaria, tuberculosis and dysentry used to be common, and it was much harder to treat dental problems and wounds back then, Dr Parsonnet said.
She said body temperatures may continue to fall, perhaps leading to longer lives in the future, but expects one day it'll level off.
The research was published this week in journal eLife.