A visiting professor is questioning claims that humans originated in response to climate change.

Andrew Barr, a researcher with the Center for the Advanced Study of Human Paleobiology and a visiting assistant professor of anthropology, released the results of his research last week and found an influx of new species, commonly explained by scientists as caused by global climate change, could have been a coincidence and not directly related to environmental changes. The report was published in Paleontological Society.

Barr created fossil records using computer simulation to demonstrate that a type of species can experience an influx without climate change as a factor. This model challenged widely-accepted notions about how humans became more intelligent and sophisticated and means that other researchers may need to rethink their theories, according to a University release.

“The idea the the origin of Homo is part of a climate-caused turnover pulse doesn’t really bear out when you carefully look at the evidence and compare it against other possible explanations,” Barr said in the release. “One implication is that we may need to broaden our search for why our genus arose at that time and place.”

Traits that differentiate humans from their ancestors could have been caused by a variety of factors, like larger brains and technological sophistication, not necessarily climate change, he said.

“We can sit in the present and tell stories of the past that make sense of our modern day adaptations,” Barr said. “But these could have evolved for reasons we don’t know.”