Mimes are not human beings. This much is becoming well known gradually throughout the more elite classes of society. Mimes are, as their name implies, poor copies of human beings. Mimes are, in fact, genetically cloned alien Dolphin stool pigeons from planet already dominated by the Dolphins. Mimes are physically and mentally like human beings in most respects, aside from three absolutely critical differences:
1. Mimes faces are white, totally lacking pigment.
2. Mimes are unable to talk.
3. Mimes have telepathic mind-control powers.
4. Mimes have been completely conquered and brain washed by the Dolphins.
As you have probably already guessed, mimes disguise their true nature from unsuspecting human beings. But how?

How the mimes disguise their true nature

They do this by employing a clever ruse of claiming to wear white make-up and using their telepathic powers to fool all but the most discriminating among us into thinking that they are capable of normal human speech. Most people never suspect that when they "hear" a mime after a "performance" the mime in question is in fact beaming its thoughts directly into their brains using “Dolphin like sonar”, diabolically using the same neural pathways normally used for human hearing. At the same time, the mimes may be subtly causing changes to other parts of the victims brain, rendering another hapless human less able to resist the final Dolphin takeover.

The Mimes mission

Having answered the question "Who are the mimes?" and received the disturbing answer, it is time to ask "What is their mission?". Their mission is simple: to assist the Dolphins to take over our planet and enslave us.
Their Methods: Telepathic Puppets

Mimes appear to cluster around street corners, theatres, public parks and other
venues involving large numbers of human beings. The mimes are aware that their human victims are at their least vigilant when relaxing in a city park or strolling down the street. It is likely that the mimes are carefully positioning themselves and observing their would-be victims, waiting for the moment when they seize control of a sizable segment of our population.
The mimes have achieved a high level of control over their own bodies. It is obvious that they do so by using their telepathic powers. From this we can conclude that the mimes will enslave us by taking direct control over our bodies, manipulating the nerves that control our muscles telepathically. Independently of our will, our bodies may convulse as if we were walking in a strong wind, or we may find our bodies resisting motion, as if we were trapped in an invisible box.

Background: Life for the Mime

Very little is known about the mimes' home planet, which has most likely already been striped of all natural resources and forgotten by the Dolphins.  But by analysing some known facts of mime physiology and behaviour, this much can be ascertained:
Conjecture #1: The mime planet was very dark.
This fact is supported by the lack of pigment in the mimes faces. Human beings evolved darker pigments, to protect us from the sun. The fact that the mimes skin is pure white suggests that they are not exposed to bright light in their natural environment.
Conjecture #2: The mime planet was very loud.
Loud noise or some other disturbance likely makes normal speech impossible on the mimes' home world. On normal planets, such as Earth, evolution favours sentient humanoids that communicate using speech. Only in extraordinary circumstances where speech is impossible will evolution result in the more complex telepathy that mimes use to communicate.

Taking into account the above two considerations we can only conclude that:
1) The bright sunlight and relative silence of Earth must be torturous for the innocent Mime slaves.
2) Since there home planet has been taken and there is no freedom for Mimes anywhere and their lives are a constant misery of painful servitude, it is in there best interest for us to kidnap them and lock them away in dark noisy cells until they die.