Stone tools influenced hand evolution in our ancestors

New research from anthropologists[1] at the University of Kent has confirmed Charles Darwin's speculation that the evolution of unique features in the human hand was influenced by increased tool use in our ancestors.

Research over the last century has certainly confirmed the existence of a suite of features in the bones and musculature of the human hand and wrist associated with specific gripping and manipulatory capabilities that are different from those of other extant great apes. These features have fuelled suggestions that, at some point since humans split from the last common ancestor of living apes, the human hand evolved away from features adapted for locomotion toward alternative functions.

Now, researchers Dr Stephen Lycett and Alastair Key have shown that the hands of our ancestors may have been subject to natural selection as a result of using simple cutting tools. In a series of experiments that used stone flakes similar to those known from Africa around 2.6 million years ago, they analysed whether variation in the hand size of individual tool users reflects differences that affect the efficiency of these simple tools to cut through a rope.

Their results, published in the Journal of Archaeological Science, show that 'biometric' variation did indeed result in a significant relationship with cutting efficiency in the experimental task.

Dr Lycett, Senior Lecturer in Human Evolution[2] at the University's School of Anthropology [3]and Conservation, explained: '140 years ago, writing from his home at Down House in Kent, Darwin proposed that the use of stone tools may have influenced the evolution of human hands.

'Our research suggests that he was correct. From a very early stage in our evolution, the cultural behaviour of our ancestors was influencing biological evolution in specific ways.'

'Technology based evolution? A biometric test of the effects of handsize versus tool form on efficiency in an experimental cutting task' (Alastair J.M.Key; Stephen J. Lycett) can be viewed online at http://dx.doi.org/10.1016/j.jas.2011.02.032[4]

Source: University of Kent