By measuring the fossil remains of Homo floresiensis, scientists have estimated its weight to be around 32.5 kg and its brain volume to be roughly 420 cm³. Plot these values on the graph in Figure 19.13A. Which hominin has the most similar relationship of brain volume to body mass? Does this information support the hypothesis that H. floresiensis is a dwarf form of H. erectus, or an alternative hypothesis? Explain.

The brain-body mass relationship refers to the correlation between the size of an organism's brain and its body mass. This relationship is often expressed through the encephalization quotient (EQ), which compares the actual brain size to the expected brain size for an animal of a given body mass. Understanding this relationship helps in assessing cognitive abilities and evolutionary adaptations among different species, including hominins.

Homo floresiensis, often referred to as the 'Hobbit,' is a small hominin species discovered on the island of Flores in Indonesia. It is characterized by its small stature, with an estimated height of about 1.1 meters and a brain volume of approximately 420 cm³. The unique features of H. floresiensis raise questions about its evolutionary lineage and its relationship to other hominins, particularly regarding whether it represents a dwarf form of H. erectus.

Dwarfism in hominins, particularly in the context of H. floresiensis, refers to the phenomenon where species evolve smaller body sizes due to environmental pressures, such as limited resources on islands. This evolutionary adaptation can lead to significant changes in morphology and behavior. The debate surrounding H. floresiensis includes whether its small size is a result of insular dwarfism or if it represents a distinct evolutionary path from larger hominins like H. erectus.