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

william sanders. a commonly held notion among the public at large and also among some of my anthropological colleagues is that non-western peoples live in harmony with nature, that they have relatively stable environmental relationships. what archaeology teaches us is that that's not true. keach: in the new world, human beings appeared for the first time more than 10,000 years before the birth of christ. over the millennia, grand city-states emerged in the tropics of mexico, guatemala and honduras. this is the realm of the ancient maya. they built magnificent cities and peopled them with the portraits of their kings. these are the ruins of copan in honduras. the mystery of the rise and fall of these maya kingdoms has fascinated archaeologists for centuries. it is a puzzle presented in 1839 by the words and etchings of explorers frederick catherwood and john stephens. "architecture, sculpture and painting, "all the arts which embellish life "had flourished in this overgrown forest. "the city was desola

for william sanders, the retreat is direct evidence of the power held by aztec kings. sanders: down below me in the flat plain of the valley of mexico is the modern town of texcoco. and that's where the king's permanent palace was located, which was a very large structure according to one of the sources of the 16th century -- had several patios and several hundred rooms surrounded by an enormous wall. apparently, he decided he needed a place to get away from it all, to get away from the business of state, from the cares of state, and so he built these pleasure gdens out here, three or four kilometers from his capital. only with extraordinary power can a ruler build himself something like this. it reflects the fact that the kings had hundreds of thousands of men available for labor projects of this type. it's perhaps one of the best indicators of political power that we have for the aztec period. keach: the builder of the gardens, nezahualcoyotl, was one of the most famous kings in mexican history. he was an accomplished warrior, but he was also a man of letters who main

williams to ricky sanders. 55 of the 145 yards, sanders would haul in on the day. skins lead 7-3. >> going in and make my plays. that's what you've got to do nowadays. if you're behind, make the plays and get the team fired up. >> reporter: bobby brister with time to consider all of his options. he selects louis all by himself. an 80-yard touchdown that left darrell green devastated. >> i just had a sense from him and the crowd that the play was over. and i looked back and just a count of two or three, and wham, the ball comes out. he catches it like a punt return and runs in for the touchdown. that really shook me up. a mistake i can't afford to make anymore. >> reporter: fourth quarter, buby wasn't done. the short connection turns into a 50-yard foot race. and the black and gold would win. steelers up by 9. cue the comeback. williams to calvin bryant from seven yards out, cutting the steelers' lead to 29-27. just 12 seconds left now. chip miller called upon for the 19-yard game-winner. earlier in the game, the rookie kicker bonked the 35-yard attempt off the righ

sanders, lakeland, florida. >> that is our broadcast tonight. thank you for joining us, i'm brian williamsre tomorrow night. good evening. sanders, lakeland, florida. >> that is our broadcast tonight. thank you for joining us, i'm brian williams, we hope to see you back here tomorrow night. good evening.

sanders, lakeland, florida. >> that is our broadcast tonight. thank you for joining us, i'm brian williams, we hope to see you back here tomorrow night. good evening. >>> "nbc bay area news" starts now. >>> good wednesday evening, everyone. thanks for joining us. we begin with a developing weather story. we want to show you this hail, lots of it right there out of gilroy this afternoon. that given to us by danielle. this afternoon lots of this hail, which is considered pretty unusual for this area, and with it came thunder and lightning creating potentially a dangerous weather situation. we want to bring in our chief meteorologist in the nbc bay area weather center who is tracking the storm. pretty odd to have that, and we've seen a