The recently discovered bone overlaid on a modern human hand. (Jason Heaton)

A human ancestor living nearly 2 million years ago may have had hands much like our own, setting it apart from other pre-humans alive at the time.

In a study published Tuesday in Nature Communications, researchers report the discovery of a bone that they believe to be part of the left little finger of an ancient hominin species, pushing the earliest "modern" hand back by around 400,000 years. In the hominin's habitat -- Tanzania, some 1.84 million years ago -- other hominins like  Paranthropus boisei and H. habilis would have been dwarfed by the modern(ish)-looking man.  Based on his hand, anyway.

[Scientists discover a new human ancestor that roamed with ‘Lucy’]

If the bone is proportional to a modern-human-like body, the man in question would have been around 5 feet 9 inches, compared to H. habilis, who stood just over 3 feet tall.


Rotating views of the pinky bone. (M. Domínguez-Rodrigo)

The as-yet unidentified species, which the researchers suspect looked like Homo erectus, is helping to shed light on the evolution of hands as we know them. Human-like hands were once thought to have evolved for tool use, but their lineage has grown more complex as the fossil record has improved. Now it seems likely that modern hands evolved earlier than we'd thought, with perhaps the biggest difference between the old and new hand shapes being a decrease in the need to climb trees.

[The human family may have evolved half a million years earlier than we thought]

According to researchers involved in the study, this bone doesn't show any signs of tree-hanging, suggesting that our ancestors could have given up climbing as much as 2 million years ago, setting us on a new evolutionary path.

Then again, it's just one pinky -- so researchers will have to find a lot more bones if they want to confirm their theories.

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