Hair initially comes from a need to keep warm. As we have evolved most of this hair has gone, but obviously some still remains! It also has a purpose to attract members of the opposite sex – certain animals are known to fluff up their hair to make them seem larger and more attractive!
As for fingers, they are there mainly to grip – initially for surfaces such as branches and later for tools. The biggest jump with evolution and with the human species comes with the addition of opposable thumbs. Try and think of any other animals that have them! They allow us to grab and grasp, as well as hold tools and climb more effectively.
What ever would we do without thumbs…
Hair is quite useful for retaining body heat, because air caught in the coat between the hairs acts as a good insulator – a bit like the air trapped between panes of glass in double glazing.
Fingers are very useful for manipulating objects- so much so that the development of our thumbs (in particular) is seen as an essential step in our evolution because it allows for the complex manipulation of objects and tool use. Having said that , I’m currnetly 1- finger typing on the phone … 😉
This is due to how we have evolved Saffron. Hair is needed to keep us warm, but as we evolved we needed less and less of it. Early man had lots of body hair to keep him warm as he lived in caves and very basic shelters. We don’t really need as much now in our modern lives but, we still need some as it is also linked to sexual attraction – think peacocks which unfurl their huge great feathers to attract a mate.
Fingers are needed to grip things and hold onto things. Again as we evolved and started making tools and using our hands more, our fingers became more adapted to this and evolved into the fingers we have today. If we don’t use our fingers over generations then we will lose them!