Final answer:
The cranial capacity of early Homo species ranged from 600 cc to 800 cc, marking a significant increase in brain size compared to earlier primates and paving the way for the larger brain sizes of more recent human ancestors.
Step-by-step explanation:
Early Homo species had cranial capacities ranging from as small as 600 cubic centimeters (cc) to as large as 800 cc. Specimens such as Homo habilis, one of the earliest members of the genus Homo, are known for having a brain size of approximately 800 cc. This represents a significant increase in brain volume compared to their predecessors and suggests a milestone in human evolution toward larger brain sizes that are characteristic of later species, including those with cranial capacities comparable to modern humans — around 1,200 to 1,400 cc.