Abjection as societal or biological?

As I was reading this, I had a hard time really buying what Longhurst was saying. While I can see some of her points, she fails to acknowledge that some abjection of fluids, for fluids like vomit and urine, is more biological than societal. She seems to focus purely on the humanitarian element, lamenting society's taboos, but fails to consider the biological element. For instance, it is evolutionarily advantageous for the person who sees his peer vomiting to be repulsed. Otherwise, he may not avoid the food that cause this in the first place. Along the same lines, nausea inducement in groups is also common. If one is in a group and someone vomits, many other people in the group will feel nauseated. While this might have societal overtones, the biology of this process cannot be denied.

On a less critical note, as I was reading this, I thought of this scene from Dr. Strangelove.