Humans' long-standing relationship with fire and the resulting exposure to burn injuries may have influenced key aspects of human evolution, according to a new study from researchers at Imperial College London, Chelsea and Westminster Hospital NHS Foundation Trust, and Queen Mary University of London.
For over a million years, humans have controlled fire for cooking, heating, and technology. This set humans apart from other species but also led to frequent exposure to high-temperature injuries. Unlike most animals that avoid fire, humans live alongside it and commonly experience minor burns throughout their lives.
The research team, publishing in BioEssays, suggests that this repeated exposure has led to unique genetic adaptations among humans. These changes are seen in genes associated with wound healing, inflammation, and immune response—traits that may have improved survival after smaller burns but can be harmful when dealing with severe injuries.
Dr Joshua Cuddihy, lead author of the study and Honorary Clinical Lecturer in Imperial's Department of Surgery and Cancer, said: "Burns are a uniquely human injury. No other species lives alongside high temperatures and the regular risk of burning in the way humans do.
"The control of fire is deeply embedded in human life - from a preference for hot food and boiled liquids to the technologies that shape the modern world. As a result, unlike any other species, most humans will burn themselves repeatedly over their lifetime, a pattern that likely extends back over a million years to our earliest use of fire.
"Our research suggests that natural selection favoured traits that improved survival after smaller, more frequent burn injuries. However, those same adaptations may have come with evolutionary trade-offs, helping to explain why humans remain particularly vulnerable to the complications of severe burns."
Comparative genomic analysis across primates revealed accelerated evolution in certain human genes linked to burn injury response. The researchers believe these genetic differences could clarify why some people heal better or worse after burns—a question Yuemin Li, PhD student at Queen Mary University of London and co-author on the study addressed: "Our study provides compelling evidence that humans have unique adaptive mutations in several key genes associated with burn injury response.
"These findings could allow us to explore in future research how genetic variations in different groups impact burn injury response, potentially explaining why some patients heal well or poorly after a burn."
Professor Armand Leroi from Imperial's Department of Life Sciences commented on the broader implications: "What makes this theory of burn selection so exciting to an evolutionary biologist is that it presents a new form of natural selection - one, moreover, that depends on culture. It is part of the story of what makes us human, and a part that we really did not have any inkling of before."
Declan Collins from Chelsea and Westminster Hospital NHS Foundation Trust added: "Understanding the evolutionary drivers that cause genetic change is an important step in burn research that will influence the way in which we look at scar formation and wound healing.
"The genetic basis for scarring variation in humans and response to tissue injury is still poorly understood, and this work will provide new angles for future research."
The study argues that because only humans regularly experience—and survive—burn injuries throughout their lifetimes due to living near fire sources, these experiences shaped not just our genetics but possibly also why animal models often fail when translating treatments for human burns. The findings could inform future directions for treating burns and understanding complications related to severe skin damage.
