How Did Cavemen Deal With The Sun e.g Sunburn or Hot Days?

People tend to adapt to the type of weather they live in. If people from a hot climate move to the antarctic or even to the UK, it is very impossible for them to adapt to the cold right away. visa verse to those from the UK unless if they were born in those parts of the world. eskimos do develop sun burnt even though they never really enjoy much sun. The same with cave men, its a blessing to bask almost daily in the sun.