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(ROOT (S (S (NP (NNP Scientific) (NN theory) (CD 4) (NNP Billion) (NNS Years)) (VP (VB Ago) (NP (DT The) (JJ first) (JJ humanoid) (NN civilization) (S (VP (TO to) (VP (VB evolve) (PP (IN in) (NP (NP (PRP$ our) (NN galaxy)) (, ,) (VP (VBN explored) (NP (DT the) (NNS cosmos))))))))))) (, ,) (CC but) (S (NP (PRP they)) (VP (VBD found) (S (NP (PRP themselves)) (ADJP (RB alone))))) (. .)))
Scientific theory 4 Billion Years Ago The first humanoid civilization to evolve in our galaxy, explored the cosmos, but they found themselves alone.
(ROOT (S (NP (DT The) (JJ first) (VBG living) (NNS cells)) (VP (MD may) (VP (VB have) (VP (VBN evolved) (ADVP (NP (QP (RB around) (CD 4) (CD billion)) (NNS years)) (RB ago))))) (. .)))