Render Artifact After Editing Makehuman Mesh

Hi,

[I’m not sure whether I should have posted this under Modeling, or under Lighting and Rendering. Since I see the problem when I render, I opted for Lighting and Rendering. Hope that’s okay.]

I am having a problem with a model which shows up only when rendered (in Cycles). Specifically, I see artifacts around the nose which look like spiky shadows, but which are not coming from the image texture. And I can’t for the life of me figure out where they are coming from.

The model is of a woman which was generated in Makehuman and then imported to Blender, where I further edited the face (although very slightly–moved vertices around) in order to bring it’s shape closer to that of a reference image I’m working off of. I did not add any new geometry to the Makehuman mesh, there are no duplicate vertices, all the normals appear to be pointing correctly outward, all the polygons are quads, etc. It all looks extremely clean to me, as far as I can tell.

The areas of the face which I edited were around the eyes, mouth and nose. In the image below one can see spiky shadows on the side of the nose which are not in my image texture:

At first I thought the problem might be in my image texture, so I replaced it with a solid color image, but the result is the same, and the shadows are still visible:

Clearly I did something which Cycles is does not like, but what? I will be appreciative of any and all advice which any have to give.

The blend file is available at:

Thanks.

Ron