The site is the remnants of a solutional cave filled with 8 metres (26 ft) of deposits from the Pleistocene era, located on the eastern side of a karstic outcrop of limestone at an altitude of 562 metres (1,844 ft). It was discovered in 1960 when the area was being mined for the mineral baryte. A miner discovered a skull in the wall of the cave, extracted it and gave it to an engineer, who kept it as a souvenir for a time. It was eventually handed over to the
The site is particularly noted for the hominid fossils found there. Ennouchi discovered a skull which he termed Irhoud 1 and is now on display in the
When comparing the fossils with those of modern humans the main difference is the elongated shape of the fossil braincase. According to the researchers this indicates that brain shape, and possibly brain functions, evolved within the Homo sapiens lineage and relatively recently. Evolutionary changes in brain shape are likely to be associated with genetic changes of the brain's organization, interconnection and development and may reflect adaptive changes in the way the brain functions. Such changes may have caused the human brain to become rounder and two regions in the back of the brain to become enlarged over thousands of years of evolution.