The first animal life in 2001: A Space Odyssey doesn't appear for 4 and a half minutes - even longer if you count the overture.
A herd of tapirs roots around in a circle, with one individual isolated at the head. It's an image that appears with so little fanfare (in a movie that's practically ALL fanfare), it's easy to miss just how weird it is.
Isolation and circles are key.
One tapir strays, and we meet the first heroes - or probably more accurately: test subjects - of the film. A group of primitive man (or at least ancestors of man (mancestors)), bunched in a circle, suspended between the warmth of the sun and the grit of the earth. The tapir encroaches and is run off with grunts. It's not a major threat, but it's a competitor and its presence seems to highlight the genuine community of our early men and women. A tight bundle without a head, a visual counterpoint to the tapir circle.
It's also a visual counterpoint to the crucial final image, and a core theme of 2001 is curiosity and wonder at how we got from the earthy community here:
I've heard the film described as technological fetishism (Susan Hayward, for one, has characterized it along these lines), but there's no Star Trek-ish sense of wonder or awe. It's sort of a reverse horror film - I can think of few films which come across so frightened with the state of things. There's a cosmic coldness which man cannot escape or control. It's the social prison of Barry Lyndon combined with the hybrid bureaucratic/technological nightmare of Dr. Strangelove.
When is man FIRST alone in the film?
When he picks up the bone and learns to control his environment.
When is man MOST alone in the film?
At the moment of death, spinning through the void, unable to stop oneself, unable to even TOUCH one's own body. Our meager control has been thrown back in our faces. We're not the masters of our fate, we're not even the masters of ourselves.
Spacesuits in particular seem to horrify Kubrick. There are direct visual parallels between the sarcophagi sleep chambers and the space suits:
Space flight in general is an unnatural experience here. It's a kind of living death, an isolating factor. Look at the pathetic desolation of Dr. Floyd's flights:
Unconscious, limp, and adrift, the film makes no real distinction between the loneliness of life in space and the loneliness of death in space:
The stewardess's ridiculous hat is a nice visual premonition of the EVA pod - and also the Star Child's spacesuit/womb. These flights are all just variations on a theme.
From Paths of Glory on, Kubrick has been afraid of formality and ritual. In his films, it breeds inhumanity. Here, characters seem to drift apart. Our social cocoons become literal:
And in the end there's not much difference between this sort of isolation:
And this ultimate, grotesque, grand isolation: