I will go against popular wisdom here and say that the Paleo recommendation for calcium is too low. Sure, the paleolithic people didn't have goats or cows with them, but they had lots of bone broths, and ate all the marrow from bones. Today, it's hard enough to find good grass-fed marrow bones (I can't find them), and we definitely don't eat all parts of the animal (not even hard-core Paleo people do). Therefore, it's my opinion that either supplementing with calcium, or eating dairy is a must. So it's not a matter that paleolithic people didn't need to supplement, but the modern society is such that we must. At least for most of us.

After going Paleo, I personally supplement with calcium occasionally, and I also eat dairy. However, I don't go for random dairy. I go for goat-only (closer to human's milk), and I only eat lactose-free probiotic kefir, home-made probiotic lactose-free yoghurt, and hard cheeses (which are lactose-free too -- no, I'm not allergic to lactose, I just avoid it to lower sugars). From cows I only eat butter and lactose-free sour cream. I don't do runny milk (when I want plain milk, I go for coconut beverages with added calcium in them). This has fixed a number of problems with my teeth (mostly sensitivity, and being transparent).

In fact, I remember when I was at the dentist last month for a routine cleaning, and when I came back, my teeth were in such a stress, that they were itching for calcium (I had an urge to drink random milk out of a carton like no other). I had to have quite some calcium that day to make my teeth happy. That day, I was calcium-depleted, even if I was supplementing/eating dairy! Which means to me that we really don't get enough in a modern diet. And yes, I also supplement with magnesium, K2 and D3, so this was NOT a case of "not absorbing" calcium. That was a case of depletion instead.

Either that, or the paleolithic people really needed calcium too, and they couldn't find enough. Just because they were "paleolithic" doesn't make them perfect in their food choices, simply because they might not have had a choice. Whose to say that the paleolithic people didn't eat eggshells too, just like most animals do when they eat eggs? One hen eggshell has as much calcium one needs for 1 day! But who eats eggshells today? NO ONE.

That's why I suggest that the conditions these people lived by are not the same as we live today. Today, we need to supplement with calcium, or eat dairy, no matter what "mainstream Paleo" says we should do. At least my own body tells me that it needs more calcium than it has in its reserves.