Are there any known clothing-less cultures that might make this research possible?
When the Spanish missionaries reached California they found the males wore no clothes in many areas.
Rather than do comparative research they were scandalized.
Here is one of the few pictures that shows people unclothed:
This was done nearly 50 years after the Europeans arrived, so it's accuracy is open to question.
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
Belief gets in the way of learning--Robert A. Heinlein
How can I possibly put a new idea into your heads, if I do not first remove your delusions?--Robert A. Heinlein
It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers