Alternative solutions to the riddle of the Sphinx? [closed]

Question

One of the oldest known riddles is the riddle (ainigma) of the Sphinx. In ancient Greek tradition the Sphinx devoured all those who failed to solve it, but she destroyed herself instead when Oedipus got the right answer.

In its best known form, it runs as follows:

What walks on four legs in the morning, two legs at noon, and three legs in the evening?

The answer is man: a person crawls on all fours when a baby, walks upright in the middle period of their life, and uses a walking stick when they are elderly.

What alternative solutions can you come up with?

Restriction

Having been advised that the question as phrased above is too broad, and after imagining theatre-goers storming out of a production of Sophocles's Oedipus the King, loudly objecting that "The Sphinx's puzzle was completely unrealistic. It's obvious there's an infinite class of possible solutions, consisting of any quadruped entity that loses two legs and then gains back one", I am adding the following restriction:

please ensure that at least one interpretation of the word 'leg' is non-literal.

Further restriction

In response to votes to keep this question closed for still being "too broad" even after the addition of the first restriction, the original poster has decided to add a further restriction as follows.

Since this question is not considered reopenable as it stands, for being too broad, please make all answers refer either to the behaviour of vicunas (aspects of their behaviour not also displayed by other camelids) or to the developing relation between advertising, participatory commercial ('social') websites, right-wing libertarianism, the work culture of computer programmers, schizophrenia, bureaucracy, and the function of ritual respect-paying to 'good faith', but not both.

Answer 1

Napoleon in George Orwell's Animal Farm:

Four legs originally (naturally).
Then starts walking on two.
Then is propped up by the blood, sweat and tears (three things you see) of the proletariat beneath him.

Further explanation for those not familiar with Animal Farm:

Napoleon was the pig in charge of a revolt that led to the animals running their own farm. Like all pigs, he walked on four legs. In chapter 10, to the shock of the other animals, the pigs started walking on two legs (and carrying whips with Napoleon as a tyrannical dictator).

The primary message of the story is as a satire of Stalinist communism where the leaders of the revolution are as oppressive to the people as the aristocrats they replaced - hence the final three legs, which is a common phrase that means sacrifice and effort (see for example http://spectator.org/articles/56615/blood-sweat-and-tears).

Answer 2

Here's a slightly more literal answer than most...

Army buddies.

In the morning, they leave on a mission, walking on four legs.

In the afternoon, one of the buddies steps on a landmine, destroying one leg. The other buddy carries the injured one back to camp where there's a medic. Two legs.

In the evening, the medic has stitched up the injured buddy's stump, and hops, with the help of his buddy, to his cot - they are now walking on three legs between them.

Answer 3

A human, or bird, or anything else that satisfies the following:

• evolved from four-legged ancestors (early primates/lizards in the case of humans/birds)
• has two legs at the current stage of evolution
• could conceivably evolve to have three legs in the future (heard of Frank Lentini?)

Answer 4

A military dog:

1. When it was born it had four legs.

2. Then it lost two legs from an exploding mine/bomb.

3. Its owner realized that a dog cannot walk on two legs and he was very stingy, so he got the dog one prosthetic leg. Now it has three legs.