As hominins diverged from other primates, which of the following appeared first?
a. Reduced jawbones
b. An enlarged brain
c. The making of stone tools
d. Bipedal locomotion

Verified step by step guidance

1. Begin by understanding the term 'hominins.' Hominins are a group that includes modern humans, extinct human species, and all our immediate ancestors. They are part of the family Hominidae, which also includes other great apes.
2. Consider the evolutionary timeline of hominins. The divergence from other primates involves several key adaptations that occurred over millions of years.
3. Examine each option in the context of evolutionary history: a) Reduced jawbones, b) Enlarged brain, c) Making of stone tools, d) Bipedal locomotion.
4. Bipedal locomotion is a significant adaptation that allowed hominins to walk upright on two legs. This adaptation is considered one of the earliest changes in hominin evolution, preceding other developments such as tool-making and brain enlargement.
5. Reflect on the importance of bipedalism in hominin evolution. It provided advantages such as energy-efficient movement and the ability to use hands for other tasks, which later facilitated tool-making and brain development.

Key Concepts

Hominin Evolution

Hominin evolution refers to the process by which humans and their ancestors evolved from other primates. This includes changes in physical traits, behaviors, and cognitive abilities over millions of years. Understanding the sequence of these evolutionary changes helps in identifying which traits appeared first as hominins diverged from other primates.

Bipedal Locomotion

Bipedal locomotion is the ability to walk on two legs, a key characteristic that distinguishes hominins from other primates. It is believed to be one of the earliest adaptations in hominin evolution, providing advantages such as energy-efficient movement and freeing the hands for tool use and carrying objects, which played a crucial role in the development of other traits.

Sequence of Evolutionary Traits

The sequence of evolutionary traits refers to the order in which specific physical and behavioral characteristics appeared in hominins. Bipedalism is considered one of the first major adaptations, followed by other traits like tool-making, brain enlargement, and changes in jaw structure. Understanding this sequence helps in answering questions about the timeline of hominin evolution.