( ( Wisdom teeth ) ( ( are ( ( vestigial ( third molars ) ) ( that ( ( human ancestors ) ( used ( to ( help ( in ( ( grinding down ) ( plant tissue ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Wisdom) (NNS teeth)) (VP (VBP are) (NP (NP (JJ vestigial) (JJ third) (NNS molars)) (SBAR (IN that) (S (NP (JJ human) (NNS ancestors)) (VP (VBD used) (S (VP (TO to) (VP (VB help) (PP (IN in) (S (VP (VBG grinding) (PRT (RP down)) (NP (NN plant) (NN tissue))))))))))))) (. .)))
Wisdom teeth are vestigial third molars that human ancestors used to help in grinding down plant tissue.
(ROOT (S (NP (NN Ground) (NN tissue)) (VP (VBZ makes) (PRT (RP up)) (NP (NP (JJS most)) (PP (IN of) (NP (NP (DT the) (NN inside)) (PP (IN of) (NP (DT a) (NN plant))))))) (. .)))