Final answer:
If the division between Homo ergaster and Homo erectus is real, then Homo ergaster is earlier and more primitive anatomically, known for transitioning towards modern human features with less sexual dimorphism.
Step-by-step explanation:
If the division between Homo ergaster and Homo erectus is real, then Homo ergaster is slightly earlier and more primitive anatomically. Homo ergaster is believed to be the ancestral form linked to Africa and is known to have exhibited certain primitive features compared to the Homo erectus associated with Asia. Differences between the two are subject to ongoing debates in the scientific community, with some researchers suggesting they should be classified as variants of the same species.
Characteristics of Homo ergaster suggest that it represented a transition towards modern human anatomy with reduced sexual dimorphism and physical proportions. Homo erectus, on the other hand, while also showing decreased dimorphism compared to earlier hominins, had a larger brain and other features more aligned with modern humans. The diversity in evolutionary changes observed in Homo erectus indicates it set the stage for subsequent human evolution.