Spencer attempted the stairs for the first time today. I found him trying it at home this morning. When we went to my sister's house this afternoon he caught on really quickly and made it up three steps before tiring out. He can't walk or even crawl with his belly off the floor, but he's climbing the stairs.
Alex is commando crawling all over the place. He's totally keeping up with Spencer. In fact, watching him, I think he's going to do an actual crawl before Spencer. That's the thing about Alex: he always defies expectations.