In 2006, researchers discovered a rock shelter in a mountainous area at Jebel Faya, about 62 miles (100 kilometers) from the Persian Gulf. As anthropologists began excavating, the site yielded evidence of human presence. Several different assemblages (in this case, groups of tools and artifacts on a single site that belonged to people of different eras) were uncovered from the Bronze and Stone ages. The oldest of these assemblages included axes, scrapers and denticulates (toothed tools used as saws) [source: Switek].
The researchers at the Jebel Faya site used a process called luminescence dating to come up with a rough idea of when the tools were last exposed to light. Crystalline materials found in rock store radiation from sunlight. When they're covered up by soil or sediment, the rocks maintain this radiation, which can be released and measured. The amount of luminescence generated when the radiation is released can be converted into an approximate age. The more luminous the radiation, the longer it's been since the rock was exposed to sunlight.
The luminescence dating showed the oldest tools found at the Jebel Faya site had last been exposed to sunlight between 100,000 and 125,000 years ago. What's more, the researchers found the tools were produced with the same methods used by groups living in East Africa around that time.
This isn't supposed to be. According to popular belief, humans didn't enter the Middle East until 65,000 years after these early tools were made [source: Reuters]. And they certainly weren't thought to have entered the area through East Africa. Human origin theories place these migrating humans not only later in history, but also coming from a different direction -- from North Africa into Asia.
Yet, these tools, along with recent remains dated from about the same period uncovered in modern-day Israel, suggest the migration of modern humans took place far earlier and along different routes than previously thought [source: Switek].
The Jebel Faya researchers point to recent evidence that the Arabian Peninsula during the era was lusher than it is today, offering migrating humans sustenance through vegetation and eating other animals. The Red Sea, which separates the peninsula from eastern Africa, may have also flowed at a lower level than today, which would allow for easier passage of humans.
Perhaps the biggest challenge to the Jebel Faya site is the lack of human remains associated with the tools. Without associated remains, it's equally possible that the discovery means we'll rewrite our understanding of tool making, rather than human migration.