enjoy seeing how both evolve 
(ROOT (VP (VB enjoy) (S (VP (VBG seeing) (SBAR (WHADVP (WRB how)) (S (NP (DT both)) (VP (VBP evolve))))))))
(ROOT (VP (VB ) (S (VP (VBG ) (SBAR (WHADVP (WRB )) (S (NP (DT )) (VP (VBP ))))))))