Standing

I walked into the nursery yesterday and found Eden standing in her crib. "Woo Hoo!" I thought," we can now, for sure, check that off the milestone list." Little did I realize that babies learn how to stand up before they learn how to sit down. Today, I had put the kids down for a nap when suddenly I heard E crying. I cam upstairs and she was standing in the crib again - getting progressively more annoyed that she was standing. I lay her down (after settling her) and she went to sleep. Shouldn't evolution had taught us how to sit down, before we learn how to stand up?