( ( Although ( ( ( this kind ) ( of ( pheromone communication ) ) ) ( is ( well-known ( to ( occur ( in animals ) ) ) ) ) ) ) ( , ( scientists ( ( thought ( it ( ( did not ) ( exist ( in humans ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Although) (S (NP (NP (DT this) (NN kind)) (PP (IN of) (NP (JJ pheromone) (NN communication)))) (VP (VBZ is) (ADJP (JJ well-known) (S (VP (TO to) (VP (VB occur) (PP (IN in) (NP (NNS animals)))))))))) (, ,) (NP (NNS scientists)) (VP (VBD thought) (SBAR (S (NP (PRP it)) (VP (VBD did) (RB not) (VP (VB exist) (PP (IN in) (NP (NNS humans)))))))) (. .)))
Although this kind of pheromone communication is well-known to occur in animals, scientists thought it did not exist in humans.
(ROOT (S (NP (NNS Pheromones)) (VP (VBP are) (VP (VBN released) (PP (IN into) (NP (NP (DT the) (NN environment)) (PP (IN for) (NP (NP (NN communication)) (PP (IN between) (NP (NP (NNS animals)) (PP (IN of) (NP (DT the) (JJ same) (NN species))))))))))) (. .)))