(CNN)The story of humankind's origins was thought to have largely unfolded in a cave with a sea view.
The earliest evidence suggesting that modern humans were capable of symbolic thought and complex behavior -- the use of ochre pigments paint and decorative items -- comes from coastal sites in Africa that date back to around 70,000 to 125,000 years ago. These types of objects give us insights into the human mind because they suggest a shared identity.
Archeologists had assumed that many of the innovations and skills that make Homo sapiens unique evolved in groups living by the coast before spreading inland. Predictable marine resources like shell fish and a more forgiving climate may have allowed more early humans in these areas to thrive. Plus a diet rich in sea food, which contains omega-3 fatty acids that are important for brain growth, may also have played a role in the evolution of the brain and human behavior.
However, new discoveries 600 kilometers (about 370 miles) inland in the southern Kalahari Desert contradict that view, and a new study suggests that early modern humans living in this region did not lag behind their counterparts living on the coast.
Some 22 calcite crystals and fragments of ostrich shell -- found in the Ga-Mohana Hill North Rockshelter in South Africa and dated to approximately 105,000 years ago -- are thought to have been deliberately collected and brought to the site. The crystals serve no obvious purpose, and the researchers suggested that the ostrich shells could have been used as a water bottle.
"They're really well-formed, white and visually striking and lovely. Crystals around the world are really important for spiritual and ritual reasons in different time periods and different places," said Jayne Wilkins, a palaeoarchaeologist at the Australian Research Centre for Human Evolution at Griffith University, Brisbane, Australia, and lead author of the study that published Wednesday in the journal Nature.
"We tried really hard to find out whether or not natural processes could explain how they got into the archeological deposits but there isn't an explanation. People must have brought them to the site."
Wilkins said that in light of these findings, ideas linking the emergence of Homo sapiens and coastal environments "needed to be rethought." She suggested that humans' origin story was more complex, involving different places and environments in Africa and different groups of early people interacting with one another and contributing to the emergence of our species.
"Before this, the Kalahari was not considered an important region for understanding the origins of complex Homo sapiens behaviors, but our work shows that it is. Ultimately, this means that models that focus on one single origin center, like the coast of South Africa, are too simplistic," she told CNN in an email.
Pamela Willoughby, a professor in the anthropology department at the University of Alberta in Edmonton, Canada, who was not involved in the research, agreed with this assessment.
"The objects they found suggest it is time to revise current thinking about the emergence of cultural innovations among early human populations," she said in a commentary that was published alongside the study.
The climate in the Kalahari 100,000 years ago would have been much different than the arid place it is now.
The newly uncovered artifacts would have been in human hands at a time of increased rainfall. The researchers said that the greater availability of water might have led to greater population densities, which could have influenced the origin and spread of innovative behavior.
Willoughby said that part of the problem in untangling the complex story of human origins is that only a few African regions have been studied in detail.
She said that the fossil record in Africa "now indicates that there does not seem to be any single pattern of technological and social development over time. Initiating surveys and excavations of lesser-known areas will help to clarify what it was that made our immediate ancestors truly modern, both biologically and culturally."
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