Haskell Wexler died the day before this Museum of Modern Art screening, and it had been his 1969 Medium Cool as much as any that gave rise to the docudrama. Most of the often unfaithful loose “based-on’s” could qualify for this amorphous, increasingly practiced genre. Certainly there is a place here, ahead of many others in the pack, for Ciro Guerra’s Embrace of the Serpent/El abrazo de la serpiente.

This is not only because this third feature from the Colombian director-writer derives from the diaries of two scientist-traveler-seekers of a century ago: German ethnology professor Theodor Koch-Grunberg and the American ethnobotanist Richard Evans Schultes. In razor-sharp b&w (with end-seconds of psychedelic color) it uses many of the techniques of narrative documentaries, which after all began life post-1907 as essentially travelogues. Both white protagonists, Theo and Evan [sic] (Jan Bijvoet and Brionne Davis), use photography together with sketches to document for science and furnish evidence of their unlikely, and perilous, adventures in the wild Amazon Basin border Department of Vaupés.

Separated by forty-some calendar years, the two adventurers are united through magnificent Karamakate, the proud probably last surviving member of his indigenous people. Suspicious and surly as a young shaman (Nilbio Torres), he is persuaded to guide deathly ill Theo and the native helper he ransomed from upriver rubber plantation slavery (Yauenkü Migue, as Western-dressed Manduca), to find other possible tribal survivors. Primarily, though, they seek to locate the sacred yakruna, from which to distill physically and spiritually healing hallucinogen medona caapi, “the most powerful of all, [which] existed before the Creation, before the Snake descended.”

Sympathetic as he at times may be, striving for rapport with natives or writing to his beloved wife in Europe, the white, however, cannot free himself and his mind, cannot become cohiuano, worthy and able to transcend material “things” of this world.

This little-ballyhooed offering in the MoMA series “The Contenders 2015 . . . bound for awards glory or cult classic” status, jumps ahead in midstream -- and subsequently will back-and-forth -- to a Karamakate (Antonio Bolivar) older, saggier, mellower now, forgetful of the man he helped and hindered decades ago, even of the meaning of his own current rock-drawings.

Evan pirogues to him, ostensibly for help in retracing that earlier journey but, it becomes more than likely, at least also to scout for new rubber trees, the harvesting of which has led greedy developed civilization and its religion of blood to enslave de facto -- the practice being legally outlawed -- Christianize, debase and destroy indigenous tribes or force them further into the jungles.

Two minutes over two hours, ES drags in places, but the total effect is powerful. It is not a facile plea for ecological considerations but, rather, a paean to a lost paradise of individual as well as group self-awareness and kinship with the natural world of Plants of the Gods and Vine of the Soul. Belief in the power of the spirit, approached through openness to liberation from the purely physical, unites the man with the jaguar with the butterflies alongside the rivers of earth and of the Milky Way.

(Released by Oscilloscope Pictures; not rated by MPAA.)