Face: Both Input and Output

The human eyes, ears, nose, and mouth can input information and substances. Simultaneously, the "face" they form serves as an important identifier and can output emotional states like joy, anger, sorrow, and happiness.

Why aren't these functions separated?

For example, why doesn't a person still input through their facial features, but others identify him by looking at his navel and judge his emotions by looking at his toes? Why not this way?

I don't understand biology and evolution well, but if I were to design it, my general thinking process would be:

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1.1. Higher positions allow for more convenient input.

1.2. Higher positions on the body are limited.

1.3. Due to 1.1 and 1.2, input is concentrated on the head, forming what we called the face.

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2.1. Input is for observation and forms the basis of observation.

2.2. I observe the external world, and the external world observes me; meanwhile, observational capacity is both important and limited.

2.3. Due to 2.1 and 2.2, the external world prioritize observing "my observation"-->observing "my input."

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3.1. When I output information, I want it to be observed, thus increasing the success rate of my output.

3.2. Due to 2.3 and 3.1, information output locations should be close to information input locations.

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4. Due to 1.3 and 3.2, the face on the head naturally bears both input and output functions, becoming a marker for observation and even memory.

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This seems like a very natural outcome.