Stone tools helped shape human hands

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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 teardrop-shaped rocks became widely used before being replaced by finer, more precise flint tips. But how our ancestors' hands evolved into a shape that could make such tools is a bit of a mystery.

Before the hand axes appeared, our ancestors had primitive wrists: good for hanging from branches, but too weak to grasp and handle small objects with much force. And no hand bones had been found to fill the gap between 1.7 million years ago and 800,000 years ago – by which time humans had developed the hands we have today. Now, a new fossil is helping bridge that gap.

In 2010, a team led by Fredrick Kyalo Manthi of the National Museums of Kenya discovered an intriguing bone in the north of the country. Carol Ward of the University of Missouri and colleagues identified it as a third metacarpal, the long bone in the palm between the middle finger and the wrist.

Like modern human metacarpals, it has a small lump at its base – the styloid. This projection helps stabilise the wrist when the hand is gripping small objects between the thumb and fingers. Isotope dating revealed the bone to be about 1.4 million years old. It is likely to have belonged to Homo erectus.

Written By: Sara Reardon
continue to source article at newscientist.com

6 COMMENTS

  1. A semi-random additional contribution by the by: there’s a pamphlet by Friedrich Engels, titled something like “labour in the transition from ape to man” that makes a claim along these lines (if you can get past the prevailing theory of the time about our origin being in asia) i.e. that the need for skilled labour forced evolutionary development towards greater dexterity and brain power, and caused a positive feedback leading to modern humans. It’s interesting reading.

    • In reply to #1 by littletrotsky13:

      A semi-random additional contribution by the by: there’s a pamphlet by Friedrich Engels, titled something like “labour in the transition from ape to man” that makes a claim along these lines (if you can get past the prevailing theory of the time about our origin being in asia) i.e. that the need for skilled labour forced evolutionary development towards greater dexterity and brain power, and caused a positive feedback leading to modern humans. It’s interesting reading.

      Little Trotsky? Friedrich Engels? very suspicious!

      S G

      • In reply to #3 by Stafford Gordon:

        In reply to #1 by littletrotsky13:

        A semi-random additional contribution by the by: there’s a pamphlet by Friedrich Engels, titled something like “labour in the transition from ape to man” that makes a claim along these lines (if you can get past the prevailing theory of the time about our origin being in asia) i.e. that the need for skilled labour forced evolutionary development towards greater dexterity and brain power, and caused a positive feedback leading to modern humans. It’s interesting reading.

        Little Trotsky? Friedrich Engels? very suspicious!

        S G

        shrug

        Bizzarly I’ve had the pseudonym for years but only been a full-fledged socialist (though I’ve been anti-capitalist since I understood it at about 14, about the same time I gave up religion) and read this stuff over the past year. It’s actually one of the duller pieces actually; I just thought it was unusual to see a political piece commenting on science managing to get the central theme correct (which, for the most part, is fairly rare)

    • In reply to #1 by littletrotsky13:

      A semi-random additional contribution by the by: there’s a pamphlet by Friedrich Engels, titled something like “labour in the transition from ape to man” that makes a claim along these lines (if you can get past the prevailing theory of the time about our origin being in asia) i.e. that the need for skilled labour forced evolutionary development towards greater dexterity and brain power, and caused a positive feedback leading to modern humans. It’s interesting reading.

      Interesting indeed but hardly surprising. Just read http://wsws.org/en/articles/2009/06/dar1-j17.html

  2. In reply to #1 by littletrotsky13:

    A semi-random additional contribution by the by: there’s a pamphlet by Friedrich Engels, titled something like “labour in the transition from ape to man” that makes a claim along these lines (if you can get past the prevailing theory of the time about our origin being in asia) i.e. that the need for skilled labour forced evolutionary development towards greater dexterity and brain power, and caused a positive feedback leading to modern humans. It’s interesting reading.

    Thank you – I was about to point to Engels.

    In “Feminist Politics and Human Nature,” Alison M. Jaggar explains this best when she writes “The notion that human beings create themselves opens up infinite possibilities for humans to control their own destiny. It may seem paradoxical that these vistas are displayed to us by a theory that lays such emphasis on the biological basis of human nature {Darwinian evolution]. Ordinarily, a philosophical emphasis on human biology is used for the purpose of announcing biologically imposed limits to social possibility. But the way in which Marxism conceptualizes the relation between human biology and human society does not even allow for the usual form of questions as to the extent of the biological determination of human nature. Just as, on the Marxist view, human nature is not conceptually distinct from non-human nature, so Marxists do not see a line between the biological and the social components of human nature. Instead, Marxist theory views human biology and human society as related ‘dialectically.’ In other words, biology and society are not, in the end, conceptually separable from each other, rather they are related in such a way that each partially constitutes the other. Human biology is seen as having permitted the development of certain types of social organization at the same time as those particular forms of social organization permitted and encouraged a certain direction in biological evolution. For instance, tool use is seen as a cause as well as an effect of bipedal locomotion. A limited bipedalism freed the hands to pick up sticks and stones; the use of these objects gave their users an evolutionary advantage that led both to more bipedalism and to more developed tool use. So Engels writes, “the hand is not only the organ of labour, it is also the product of that labour.” Of course, the mutual interaction between human biology and human society still continues as humans continue through praxis to modify and develop human nature. For instance, science is still expanding our conceptions of what is biologically possible, from sporting achievements to test-tube babies and flights to the moon. The expansion of biological possibility, resulting from social developments, in turn expands the possibilities of social organization. “

    Jaggar then goes on to point out that this methological paradigm – the idea that biology too has a dialectially mediated history, and not necessarily one that is so glacially slow that it is “irrelevant to the present” – can also be applied to differences of sex and gender such as reproduction and gender dimorphism (even though Marx and Engels themselves, inconsistently with their own fundamental assumptions, took human sex differences as biologically given).

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