Question

The accompanying figure shows that humans have thicker thumb metacarpals than chimpanzees or bonobos, with broader heads. This is directly correlated with humans' ________.

1) bar-shaped central portion of the hyoid bone

2) increasing dependence on meat in the diet

3) more elaborate thumb musculature and better precision grip

4) loss of the ability to knuckle-walk

5) loss of an arboreal (tree-based) lifestyle

Answer 1

The thickened thumb metacarpals and broader heads in humans are directly correlated with the development of more elaborate thumb musculature and a better precision grip, allowing for intricate manipulation and tool use.

Step-by-step explanation:

The figure indicating that humans have thicker thumb metacarpals than chimpanzees or bonobos, with broader heads, is directly correlated with humans' more elaborate thumb musculature and better precision grip. This anatomical feature enhances the ability to perform precise movements and manipulate objects, which is a key aspect of human tool use and dexterity. Contrasting with nonhuman primates, the human opposable thumb allows for a stronger and more precise grip, enabling various activities like writing, crafting tools, and using complex machinery.

Primates, including humans, have evolved certain traits such as opposable thumbs and hands adapted for climbing or brachiation, which are evident in their arboreal heritage. However, humans have developed unique hand characteristics due to their different evolutionary path, which emphasizes manual dexterity and precision over climbing ability.