How could sexual dimorphism explain differences among Homo habilis fossils?

In the study of Homo habilis, the concept of sexual dimorphism—the physical differences between males and females of the same species—has been proposed to explain the significant variation observed in the fossil record.12

Paleoanthropologists have frequently suggested that differences in cranial capacity among H. habilis specimens may reflect sexual dimorphism, with larger skulls potentially representing males and smaller ones representing females. Under this hypothesis, the diverse range of brain sizes and skeletal features found in East African assemblages would be attributed to a single, highly dimorphic species.1

However, this interpretation remains a subject of scientific controversy. Some researchers argue that the observed variations in skull shape and morphology are not easily explained by sex alone. Because certain smaller skulls deviate from the morphology of large-brained H. habilis in ways unrelated to sexual characteristics, some scientists propose that the fossils actually represent two distinct species: H. habilis and H. rudolfensis. Consequently, the debate continues over whether the fossil diversity is a result of natural biological variation within one group or evidence of multiple hominin species.13