mutations that allow voluntary control of normally involuntary muscles?

Simfish

I know that such mutations would be harmful to the phenotype and thus there would be selective pressure against them. Nonetheless, do they exist? (and are there any conditions associated with them?)

jim mcnamara

My opinion only.

It would take more than a single mutation to let this happen. The sympathetic and parasympathetic systems (the ones I'm on about anyway) go thru different plumbing, ie., nerve connections, than do regular motor neurons. And they ultimately connect to different parts of the brain. Lots and lots of changes required.

I do not know of any direct "two-way" connections like you mention. Some animals with neural nets, like jellyfish, might be construed to meet your requirements.

There are examples of humans who have learned to control heart rates, for example, masters of yoga.

picklefeet

I can think of one example in humans. The epiglottis is the flap that covers your trachea when your swallowing. A belch happens when air goes into your stomach. Like some people I can control my epiglottis (which is usually involuntary) so that it covers my trachea when inhaling. This causes the air that would normally go into my lungs to go into my stomach. I have not tried keeping my trachea open while swallowing because that would result in choking.