I think Pon Farr is pretty clearly presented as biological. It's a seven year cycle. Now this makes me wonder as the figure of seven years presented for the understanding humans. Meaning that Pon Farr happens roughly every seven earth years. Or are these Vulcan years? If they are Vulcan years, what are the chances that Vulcan and earth years would just happen to be the same? Also why would it be every seven? It would make much more sense that it would happen on a yearly cycle rather than an arbitrary seven. But maybe one vulcan year is roughly equal to seven earth years. This would make the seven year cycle seem less arbitrary.
Concerning Romulans I would say that have it too. However, the forehead ridges may be evidence of interbreeding with other species. If this is the case the seven year cycle may have been thrown off as a result of them being hybrids.
Concerning Romulans I would say that have it too. However, the forehead ridges may be evidence of interbreeding with other species. If this is the case the seven year cycle may have been thrown off as a result of them being hybrids.