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Stone tools helped evolve the shape of human hands
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Stone tools helped shape our hands Sara Reardon
the bone to be about 1.4 million years old. It is likely to have belonged to Homo erectus. Hand bones of early Homo erectus are almost unknown, says Richard Potts of the Smithsonian Institution in Washington, DC. “Having such a well-preserved specimen begins to answer questions about hand evolution,” he says. “This is an exciting find,” agrees Mary Marzke of Arizona State University in Tempe. It shows that our ancestors’ hands were already
AROUND 1.7 million years ago, our ancestors’ tools went from basic rocks banged together to chipped hand axes. The strength and dexterity needed to make and use the latter quickly shaped our hands into what they are today – judging by a fossil that belongs to the oldest known anatomically modern hand. The 1.7-million-year-old Acheulean hand axes were some of the first stone tools. Over the next million years, these chunky “The forceful, repetitive teardrop-shaped rocks became widely used before being replaced processes of tool use would have made strong by finer, more precise flint tips. hands desirable” But how our ancestors’ hands evolved into a shape that could make such tools is a bit of a evolving into their modern form mystery. 1.4 million years ago. The forceful, Before the hand axes appeared, repetitive and sustained processes our ancestors had primitive of tool use, such as digging with wrists: good for hanging from rocks, would have made stronger branches, but too weak to grasp hands desirable, says Marzke. and handle small objects with This would have been much force. And no hand bones particularly useful for knocking had been found to fill the gap off flakes to form and sharpen between 1.7 million years ago and hand axes, says Potts. Once the 800,000 years ago – by which important wrist features were time humans had developed the in place, it became easier for hands we have today. Now, a new later hominids to make smaller, fossil is helping bridge that gap. finer tools. In 2010, a team led by Fredrick Because the fossil is younger Kyalo Manthi of the National than the first tools, Ward’s team Museums of Kenya discovered believe it is the first evidence of an intriguing bone in the north anatomy evolving to suit a new of the country. Carol Ward of technology. As stone tools became the University of Missouri and more widespread, those who had colleagues identified it as a third the wrist structure to use them metacarpal, the long bone in the would have had an evolutionary palm between the middle finger advantage over their weakerand the wrist. wristed kin. “The way we look Like modern human today has been shaped by our metacarpals, it has a small lump behaviour over millions of years,” at its base – the styloid. This says Ward. She presented the projection helps stabilise the wrist research at this week’s meeting when the hand is gripping small of the American Association objects between the thumb and of Physical Anthropologists in fingers. Isotope dating revealed Knoxville, Tennessee. n
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13 April 2013 | NewScientist | 11
Stone tools helped shape our hands Sara Reardon
the bone to be about 1.4 million years old. It is likely to have belonged to Homo erectus. Hand bones of early Homo erectus are almost unknown, says Richard Potts of the Smithsonian Institution in Washington, DC. “Having such a well-preserved specimen begins to answer questions about hand evolution,” he says. “This is an exciting find,” agrees Mary Marzke of Arizona State University in Tempe. It shows that our ancestors’ hands were already
AROUND 1.7 million years ago, our ancestors’ tools went from basic rocks banged together to chipped hand axes. The strength and dexterity needed to make and use the latter quickly shaped our hands into what they are today – judging by a fossil that belongs to the oldest known anatomically modern hand. The 1.7-million-year-old Acheulean hand axes were some of the first stone tools. Over the next million years, these chunky “The forceful, repetitive teardrop-shaped rocks became widely used before being replaced processes of tool use would have made strong by finer, more precise flint tips. hands desirable” But how our ancestors’ hands evolved into a shape that could make such tools is a bit of a evolving into their modern form mystery. 1.4 million years ago. The forceful, Before the hand axes appeared, repetitive and sustained processes our ancestors had primitive of tool use, such as digging with wrists: good for hanging from rocks, would have made stronger branches, but too weak to grasp hands desirable, says Marzke. and handle small objects with This would have been much force. And no hand bones particularly useful for knocking had been found to fill the gap off flakes to form and sharpen between 1.7 million years ago and hand axes, says Potts. Once the 800,000 years ago – by which important wrist features were time humans had developed the in place, it became easier for hands we have today. Now, a new later hominids to make smaller, fossil is helping bridge that gap. finer tools. In 2010, a team led by Fredrick Because the fossil is younger Kyalo Manthi of the National than the first tools, Ward’s team Museums of Kenya discovered believe it is the first evidence of an intriguing bone in the north anatomy evolving to suit a new of the country. Carol Ward of technology. As stone tools became the University of Missouri and more widespread, those who had colleagues identified it as a third the wrist structure to use them metacarpal, the long bone in the would have had an evolutionary palm between the middle finger advantage over their weakerand the wrist. wristed kin. “The way we look Like modern human today has been shaped by our metacarpals, it has a small lump behaviour over millions of years,” at its base – the styloid. This says Ward. She presented the projection helps stabilise the wrist research at this week’s meeting when the hand is gripping small of the American Association objects between the thumb and of Physical Anthropologists in fingers. Isotope dating revealed Knoxville, Tennessee. n
Find your hero (or heroine) on New Scientist Connect – there are plenty to choose from. Meet like-minded people who share similar interests to you – whether you’re looking for love, or just to meet someone on the same wavelength, no matter where you are in the world. Start your search now at: http://dating.newscientist.com
13 April 2013 | NewScientist | 11