uv mapping artifacts

so, the ONLY difference between the two meshes is that one is subdevided. notice how the low poly version kinda cracks, and it has nothing to do with the UVs. they are stright.
i think anyone who has an answer to this knows what im talking about, and my question is, why does this happen? and is there any way around it that does not involve subdeviding the mesh?

here is the actuall model. in case the image above was confusing.