Do these two series need to be read in order? I scored a few of the First North Americans books at Goodwill (Wolf, Sea, River), but they're not in order :( and I was wondering if they're stand-alone books in the series, or if I should try to get the others and read them in order. BTW, I had no idea there were so many of them when I bought these three, lol.

Also, of the Earth's Children series, I have Clan of the Cave Bear and bought Plains of Passage at Goodwill, thinking it was the next in line. I see now there are more between these two and was wondering if this series also should be read in order.

Thanks so much!