In ancient period hands were used to collect food and to save themselves. Gradually men learnt to cook food, to make tools for their own purpose, this change in habit brings perfection in their hand. Similarly, there is an increase in the ability to communicate with others and develop community behaviour. But as in ancient period, men still eat hard nuts and hard roots (though they often take soft food also). Thus change in diet is the most irrelevant change in the evolution of man.