Final answer:
Apes possess traits suited for arboreal living such as longer arms and a more mobile shoulder joint while hominins, like humans, are unique for their consistent bipedal locomotion. The most defining feature of hominins is their adapted anatomy for walking on two feet. Key characteristics of early hominins include increased brain size and changes in teeth and jaw structures.
Step-by-step explanation:
Differences Between Apes and Hominins
The traits that apes have which hominins lack largely pertain to their adaptations to live in an arboreal (tree-dwelling) environment. These can include longer arms relative to leg length, a more mobile shoulder joint, and sometimes the presence of a tail in some species. In contrast, hominins have traits that provide them with the ability to walk upright consistently on two feet, known as bipedalism. This includes anatomical changes in the spine, pelvis, and lower limbs. The arguably most defining feature of being a hominin is bipedal locomotion, which distinguishes them from other primates.
Key Characteristics of Hominins
Early hominins exhibited key characteristics such as an increased brain size, a more parabolic dental arcade, and reduced canine teeth size compared to their ape relatives. Environmental forces that may have contributed to these changes include a shift from forested environments to savanna-like habitats, which may have favored bipedal walking as a more efficient means of locomotion over larger distances while foraging or avoiding predators.