When you say constipation, what exactly do you mean? Don't worry, we're all used to poop talk here
How long have you been primal? Any sudden dietary change, especially one that reduces your dietary fibre, can cause constipation. But usually this abates in a few weeks. Interestingly, rapidly increasing your fibre intake can also cause this effect.
Just keep up the fluids (the less water removed from the stool, the softer it will be), eat fat (stimulates the gastrocolic reflex, causing bowel contractions) and try to keep your fibre pretty constant for a while.
"Thanks to the combination of meat, calcium-rich leaf foods, and a vigorous life, the early hunter-gatherers were robust, with strong skeletons, jaws, and teeth." - Harold McGee, On Food And Cooking: The Science and Lore of the Kitchen