This 'laziness' paired with an inability to adapt to a changing climate likely played a role in the species going extinct, according to lead researcher Dr. Ceri Shipton of the ANU School of Culture, History and Language.
"To make their stone tools they would use whatever rocks they could find lying around their camp, which were mostly of comparatively low quality to what later stone tool makers used.
This is in contrast to the stone tool makers of later periods, including early Homo sapiens and Neanderthals, who were climbing mountains to find good quality stone and transporting it over long distances.
Not only were they lazy, but they were also very conservative.
The sediment samples showed the environment around them was changing, but they were doing the exact same things with their tools.
There was no progression at all, and their tools are never very far from these now dry river beds. I think in the end the environment just got too dry for them."
The excavation and survey work was undertaken in 2014 at the site of Saffaqah near Dawadmi in central Saudi Arabia.