“Finger bone points to early human exodus” http://www.bbc.com/news/science-environment-43700703
The climate in Saudi Arabia 85,000 years ago was very different to the modern day.
Monsoon rains created lush lakes, inhabited by animals much like hippos. Wild cattle and antelope also appear to have migrated from Africa at this time.
The fossil record at Al Wusta shows a rich variety of animal life, alongside stone tools that closely resemble those used by Homo sapiens.
Dr Groucutt believes humans may have chosen to move in to this inviting environment.
"The interesting thing," he told BBC News, "is that in the past some people have said we couldn't really spread into Asia until we had complex tools. [Our findings] suggest that that kind of migration didn't really reflect a technological breakthrough, but reflects climate change."
Recent work in South Africa also points to the influence of changing climate on human evolution*3.
Although it is hard to determine from the Saudi Arabian site, human occupation of the area seems to have been short-lived; restricted to a few hundred or a couple of thousand years.
It is not known whether the population died out or simply chose to move on.
"The great mystery now is what happened to these people," added Dr Groucutt.
Genetic evidence suggests all living non-Africans trace their ancestry to an exodus from the continent around 60,000 years ago. Researchers are now trying to reconcile this DNA data with the mounting archaeological evidence that Homo sapiens was present outside Africa much earlier.
Kiona N. Smith “Saudi Arabian fossil find puts finger on the story of human dispersal” https://arstechnica.com/science/2018/04/saudi-arabian-fossil-find-puts-finger-on-the-story-of-human-dispersal/
Sarah Gibbens “88,000-Year-Old Finger Bone Pushes Back Human Migration Dates” https://news.nationalgeographic.com/2018/04/saudi-arabia-finger-human-migration-homo/
Ruth Schuster “85,000-year-old Homo Sapiens Bone Found in Saudi Arabia Rewrites Human History” https://www.haaretz.com/archaeology/MAGAZINE-85-000-year-old-homo-sapiens-bone-found-in-saudi-arabia-1.5980752
*2:See Huw Groucutt et al. “Homo sapiens in Arabia by 85,000 years ago” https://www.nature.com/articles/s41559-018-0518-2.epdf
*3:See Mary Halton “Changing environment influenced human evolution” http://www.bbc.com/news/science-environment-43401157