What It Means to Be Human
Doctor Who, on the one hand, has spent a great deal of time discussing the key qualities of human nature; most recently, a handful of Daleks tried once again to use the "human factor" to give them an edge over their enemies, seeking to exploit our innate aptitude for war, only to be undone by the human sense of compassion and justice (season 3's "Daleks in Manhattan"/"Evolution of the Daleks"). The Doctor prizes these qualities in humanity and frequently cites them as both justification for saving and protecting Earth and even as a model for his own behavior.
At the same time, however, the Doctor's alienness and aloofness has been consistently maintained; though he grew to love Rose Tyler and some of his other companions (in particular, Sarah Jane Smith), both his capacity to outlive every other mortal he encounters and his driving ambition to combat evil create a permanent barrier to ordinary romantic bonding.
These twin premises -- the good/evil duality within the human soul and the Doctor's alien inhibitions -- have never been more brilliantly explored than in Paul Cornell's two-part story, "Human Nature"/"The Family of Blood."
The story is adapted by Cornell from his widely respected 1995 Doctor Who novel (also called Human Nature, but featuring the Seventh Doctor and Bernice Summerfield, and with various other differences). This version starts with the Doctor on the run from beings who can trace his Time Lord physiology anywhere in time and space. Because the beings have a brief lifespan, the Doctor elects to hide from them for the few months it will take them to die.
Finally, John Smith For Real
The Doctor uses a Chameleon Arch to literally become human. The Arch, providing memories of his human life, distills his Time Lord essence into a fob watch.
He ends up as a schoolmaster named John Smith in 1913 Britain, where the beings (who call themselves the Family) eventually find traces of his scent. Taking over local humans, they start closing in on the Doctor, but Martha, who's been acting as Smith's maid, realizes one of her coworkers is possessed and runs to get her bewildered master to open the watch. The watch, unfortunately, has been lifted by a sensitive boy who seems to recognize something of its nature.
Smith is withdrawn as a human, but has grown close to the school nurse, Joan, a widow who seems to be falling in love with him and is willing to prod the recalcitrant Smith into recognizing that he's feeling the same. Meanwhile, Smith, dreaming of his life as a Time Lord, has taken to writing and sketching his dreams in what he calls "The Journal of Impossible Things."
The Family, seeking to flush the Doctor out, threatens the lives of the students and the surrounding village; Smith at first responds to this by marshalling the students as a military battalion to fight off attack, but repelled by the idea of slaughter he then calls on the students to escape and retreat instead. The crisis finds Smith and Joan, apprised of the Doctor's earlier life by Martha as corroborated by the journal, agonizing over whether the Doctor must be retrieved to prevent the deaths of dozens of innocent humans -- since this would effectively mean that John Smith must die.
A Masterful Evocation of a Powerful Idea
David Tennant proves his range as an actor by essentially creating a new character for John Smith: it's both a coalescence of the Doctor's human side and an expansion of it. Entirely ignorant of the Doctor's frenetic obsession with saving the universe, Smith is nothing more or less than a good, ordinary man. And as an ordinary man he can engage in the two pursuits denied him, or which he denies, as a Time Lord: love and war.
Tennant evokes Smith's humanity and agony so intensely that, despite knowing all that is at stake, we want more than anything for John Smith to live. The reestablished Doctor that we see after this is once again closed and distracted, creating a powerful sense of loss which is keenly felt not only by us and by Martha, but by the Doctor himself.
The writing and production are both excellent. Of course small touches are inserted for the fans: Smith says his parents' names are Sydney and Verity, an almost touching reference to show creators Sydney Newman and Verity Lambert. Even more brilliant is the "Journal of Impossible Things," which includes sketches of various people and beings from the Doctor's past, including the faces of all of the Doctor's past selves -- a comforting solidification of the continuity between classic and new Doctor Who. The sketches and surrounding scrawled text are positively haunting, an embodiment of a life that Smith finds absorbing and yet, simultaneously, unsettling. The atmosphere of the story, with the palpable presence of World War I looming only months away, likewise underscores the scale of what human nature is capable of.
The Bottom Line
The new series of Doctor Who has had its share of trivial run-arounds. But increasingly the program has broadened and deepened, honing its ability to define the Doctor and the humans he both defends and feels apart from. In "Human Nature" we go beyond even the classic split-personality stories like Star Trek's "Enemy Within," because we're not dealing with something as simple as a Good Doctor and an Evil Doctor. What's at stake is what the Doctor has given up by being a Time Lord, the Lonely God as he is sometimes called -- and whether, confronted with full realization of what he's given up, whether he would consciously choose to do so again.