Crawling lessons

This actually happened about 2 months ago, but it's so cute I wanted to share it.  Both babies learned to crawl "wounded soldier" style at a little over 9 months old.  At about 11 months, Christopher figured out how to crawl up on his hands and knees, and he realized that he could go faster that way.  One day I saw them in the living room.  Alexander was sitting and watching Christopher.  Christopher crawled on his hands and his knees past Alexander by about 5 feet, then stopped, deliberately looked at Alexander, and crawled back by him, again going past him by about 5 feet.  Again he stopped and gave Alexander a speaking glance, and then did it again.  I watched him do this about 4 times at least.

Now what other interpretation can you give to this behavior except that Christopher was giving Alexander crawling lessons?  It took him a little longer, but now they both go really fast. Now that they are 13 months old, they are both starting to take steps.

I was thinking about crawling and how quickly it passes out of our lives.  We do it for a few months and then we are on to bigger and better means of mobility.  I used to ride my bike a lot, until the day I got my driver's license.  I haven't been on one since.  The last couple of days Ryan, our 3 year old, has been crawling around on the floor with the babies, and they think it's hysterical!  It's really quite a sight, to have three giggling boys crawling around.  But what I find interesting is that the babies know that Ryan shouldn't be crawling - that's why it's funny to them.  I wonder if they know that once they master walking, they won't be crawling anymore.