Final answer:
The small size of Homo floresiensis compared to Homo sapiens can be explained by island dwarfism, an evolutionary adaptation to limited resources on the island. Alternatively, H. floresiensis may be descendants of earlier hominins like Homo erectus that evolved after becoming isolated, with their small brain size not impeding their cognitive abilities.
Step-by-step explanation:
Among the various hypotheses proposed to explain why Homo floresiensis was significantly smaller than Homo sapiens, two suggestions stand out. Firstly, the theory of island dwarfism suggests that on islands where resources are limited, large species such as the ancestors of H. floresiensis might evolve to be smaller over time to adapt to these environmental constraints. This phenomenon is also observed in other species, like the dwarf elephant called Stegodon, which lived alongside H. floresiensis.
The second hypothesis is that H. floresiensis could be a descendant of an earlier hominin such as Homo erectus that evolved independently after becoming isolated on the island. Their small size could be an evolutionary response to the availability of resources or the lack of large predators on the island. Their uniquely small brain size, compared to their body size, doesn't necessarily indicate lower intelligence, as evidenced by their ability to use tools and fire similarly to other Homo species.