The inspiration for this volume of contributed papers stemmed from conversations between the editors in front of Chuck Hilton's poster on the determinants of hominid walking speed, presented at thel998 meetings of the American Association of Physical Anthropologists (AAPA). Earlier at those meetings, Jeff Meldrum (with Roshna Wunderlich) had presented an alternate interpretation of the Laetoli footprints based on evidence of midfoot flexibility. As...