archaeologist william sanders. i think all human societies are the product of a process of cultural evolution. in general, this evolution leads to an increase in the size of societies, an increase in the complexity of their interaction and institutions. it also leads to more economic interdependence among households within a society, and among societies. keach: to trace the evolution of human societies in the new world, an archaeological team comes here to mexico's tehuacan valley. the team is led by veteran archaeologist scotty macneish. they are seeking evidence of the first inhabitants of the valley. when macneish first excavated here in 1962, he discovered a time capsule of human occupation at a site called purron cave. macneish: here we are back at purron cave. we really haven't dug in it in almost 30 years. walls all preserved. even the trowel marks we made to mark off strata are still preserved and we have all sorts of neat floors of charcoal one on top of the other. the amazing thing about this cave is that

that didn't stop jerry rice who drafted orakpo to trade him to team sanders for kolths linebacker ryan mathis. tackle trent williams making his second trip to hawaii and running back alfred morris playing in his first pro bowl game, all three on team sanders. the pro bowl kicks off tonight 579:30. you can watch the game right here on nbc4. >>> in hockey the capitals finally broke out of their slump thanks in large part to their captain. alex ovechkin missed the previous two games with an injury. the caps still have a long way to go to climb back in the standings after losing seven straight games. it's a good start in montreal yesterday. ovechkin's first game back after missing time with a groin injury. scored the caps first goal and in a giving mood, feeding casey well man in the third period, a goal and assist for ovechkin. brandon holcomb held on for the shutout. this team is excited about that 5-0 victory. they understand what led to that success. >> it's always hard work. if you do that, you're going to create chances. we're going to build off of this and get more wins. >> good win for the boys and the whole te