Numbering Introduction and Conclusion?
It's not field-dependent, it's a journal-dependent issue. Some use a format where everything is numbered, some use a format where nothing is numbered, and still others leave it up to the authors to decide.

However, when sections are numbered, everything in the main text should be numbered, including the introduction and conclusions. You don't skip numbering those sections but add numbers for the rest. That doesn't make any sense. (End matter such as acknowledgments and supporting information may be handled separately.)

The best advice is check the style guide for your journal.