Abos are homo erectus, the human species that existed about 1.5 million years ago.
Skull of a homo erectus above. Note the brow.
Here is a study comparing the brain sizes between Abos and Whites:
The abo brain sizes are comparable to those of the homo erectus based on archeological findings.
There are different kinds of ancient men. The khoisan are probably the closest to the ancient homo sapiens, while Abbos probably came from homo erectus. And Europeans are a mix of homo sapiens and Neanderthals.
They have found homo erectus skulls dating back just 40,000 years ago, and it is said that Abbos have lived in Australia for at least 50,000 years. Maybe they came from homo sapiens venturing out of Africa, say 70,000 years ago, who then met up with homo erectus in Asia, mixed up and then ended up in Australia?
According to the above couple of links, they are not homo erectus related, but they do have that devonian blood. and their ancestors may have encountered homo erectus 50kyrs ago.