( ( ( Darwin and ) Wallace ) ( ( proposed ( ( ( ( ( ( ( the theory ) ( of ( evolution ( by ( natural selection ) ) ) ) ) , ) ( ( the change ) ( in ( ( the characteristics ) ( of ( organisms ( from ( generation ( to generation ) ) ) ) ) ) ) ) ) , ) or ) ( descent ( with modification ) ) ) ) . ) )
(ROOT (S (NP (NNP Darwin) (CC and) (NNP Wallace)) (VP (VBD proposed) (NP (NP (NP (DT the) (NN theory)) (PP (IN of) (NP (NP (NN evolution)) (PP (IN by) (NP (JJ natural) (NN selection)))))) (, ,) (NP (NP (DT the) (NN change)) (PP (IN in) (NP (NP (DT the) (NNS characteristics)) (PP (IN of) (NP (NP (NNS organisms)) (PP (IN from) (NP (NP (NN generation)) (PP (TO to) (NP (NN generation)))))))))) (, ,) (CC or) (NP (NP (NN descent)) (PP (IN with) (NP (NN modification)))))) (. .)))
Darwin and Wallace proposed the theory of evolution by natural selection, the change in the characteristics of organisms from generation to generation, or descent with modification.
(ROOT (S (NP (NP (NNP Theevolution)) (PP (IN by) (NP (JJ natural) (NN selection) (NN theory)))) (VP (VBZ explains) (SBAR (WHADVP (WRB how)) (S (NP (NP (NNS populations)) (PP (IN of) (NP (NNS organisms)))) (VP (MD can) (VP (VB change) (PP (IN over) (NP (NN time)))))))) (. .)))