Which one of the following changes involved is irrelevant in evolution of man?

1. perfection of hand for tool making
2. change of diet from hard nuts and hard roots to soft food
3. loss of tail
4. increase in the ability to communicate

Simple stonetools were made and used to slice raw meat and crush raw vegetables before chewing on them by primitive man. Similarly, there is an increase in the ability to communicate with others and develop community behaviour. Loss of tail takes a great role in course of evolution.

But as in ancient period, men still eat hard nuts and hard roots .Thus answer is 2^ndoption which is irrelevant in evolution of man.