( ( ( Evolutionary pigmentation ) ( of ( the skin ) ) ) ( ( was ( caused ( by ( ( ultraviolet ( ( -LRB- ( UV -RRB- ) ) radiation ) ) ( of ( the sun ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Evolutionary) (NN pigmentation)) (PP (IN of) (NP (DT the) (NN skin)))) (VP (VBD was) (VP (VBN caused) (PP (IN by) (NP (NP (JJ ultraviolet) (PRN (-LRB- -LRB-) (NP (NNP UV)) (-RRB- -RRB-)) (NN radiation)) (PP (IN of) (NP (DT the) (NN sun))))))) (. .)))
Evolutionary pigmentation of the skin was caused by ultraviolet (UV) radiation of the sun.
(ROOT (S (NP (NP (NNP Exposure)) (PP (TO to) (NP (JJ ultraviolet) (NN radiation)))) (VP (MD can) (VP (VP (VB increase) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN pigment)))) (PP (IN in) (NP (DT the) (NN skin)))) (CC and) (VP (VB make) (S (NP (PRP it)) (VP (VB appear) (NP (JJR darker))))))) (. .)))