Figure 3.5

A tree diagram (phylogeny) linking human species. Dotted bars indicate tentative time ranges. The broad outline of the tree is established, but new discoveries may alter the proposed connections between the branches.

precision grip that is well suited for opening a jar, writing with a pencil, or flaking stone. The chimpanzee/human difference is manifest in the first or thumb metacarpal, the bone at the edge of the palm that runs between the wrist and the thumb itself. In chimpanzees, the thumb metacarpal is relatively short, and it is narrow, particularly at the end where it articulates with the first bone (phalange) of the thumb (Figure 3.6). In humans, it is relatively longer and broader, and in combination damaged after death damaged after death broad broad shaft broad broad shaft narrow

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