They need to dig deeper, but the boys with the shovels are loathe to do that, because they have convinced themselves there isn't anything down there except dirt & rocks.
The only thing that is certain is that the taxonomists really screwed up our specie's designation. It should be Homo Meanderingcuss, because that is the one thing we have always done: meander all over the place; stop and maul a locality for a while, then move elsewhere, where the mooching is easier.