However, for our early ancestors, the use of thumbs was much simpler. Strong and agile thumbs mean hominins could create better tools.

As mundane as it may seem, most of our modern-day lives revolve around the use of our opposable thumbs. From holding a hammer to texting, most of us are unaware of how much we rely on our thumbs’ dexterity.

However, for our early ancestors, the use of thumbs was much simpler. Strong and agile thumbs mean hominins could create better tools and wield bones and stones for hunting.

Because developing opposably thumbs propels our ancestors to make and use tools, eat more, and grow bigger brains, researchers wonder whether thumbs were exclusive to the Homo genus or was it seen in earlier species.

How Opposable Thumbs Were Used By Early Men

A new study published in the journal Current Biology combines ancient evidence of fossil phalanges and thumbs with muscle modeling to conclude that South African Hominins boasted capable, flexible thumbs much like ours roughly 2 million years ago.

Katerina Harvati, author and a paleoanthropologist from the Senckenberg Center for Human Evolution and Paleoenvironment, Germany, says, “It is remarkable that such a level of thumb dexterity would be observed in hominins alive 2 million years ago.”

The timeline is vital since it was before any major evolutionary events, including the rise of large-brained Homo erectus roughly 1.9 million years ago and dispersal outside of Africa about 1.8 million years ago. It also predators the replacements of stone tools by complex Acheulean handaxes roughly 1.76 million years in the past.

Harvati explains that thumb dexterity provided an evolutionary advantage that enables the subsequent gradual development of culture.

Longer fingers and shorter thumbs were vital for climbing. However, as early humans sought out life in the trees and begun to manipulate objects, shorter fingers and longer thumbs produced better hand assembly.

As time passed, natural selection refined anatomical changes based on how early humans used their hands and which were most rewarding.

Evolution by Dexterous Thumb

Tracy Kivell, a paleoanthropologist who specializes in the morphology of primitive hands at the University of Kent who was not involved in the study, notes that many primates with different hands were capable of powerful and precise grips.

Humans, however, excel at precision grips that match the pad of the fingers to the pad of the thumbs.

Kivell explains, ” Experimental studies show that humans use forceful precision grips when they make and use stone tools, so it’s often thought that the ability in humans evolved in response to these tools.”

Anthropologists and researchers have spent time comparing thumb, finger, and hand fragments left by various species across the many branches of the human species over millions of years old to see where and when the ability developed.

Although a straightforward comparison of the fragments and their similarity to our own is useful, it doesn’t show the complete story. In nature, differently shaped and formed parts may operate and perform the same way.

Originally published at The Science Times