diff --git a/CHANGELOG b/CHANGELOG
index 5fd9a12..fa2cd55 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Optimize Element#up/down/next/previous. [Dylan Bruzenak, Nick Stackenburg, Andrew Dupont]
+
 * Handle case-sensitivity in Selector tag names better. Closes #5052. [mexx, Andrew Dupont]
 
 *1.6.0.1* (December 4, 2007)
diff --git a/src/dom.js b/src/dom.js
index a2d7240..284eb3f 100644
--- a/src/dom.js
+++ b/src/dom.js
@@ -220,32 +220,31 @@ Element.Methods = {
     element = $(element);
     if (arguments.length == 1) return $(element.parentNode);
     var ancestors = element.ancestors();
-    return expression ? Selector.findElement(ancestors, expression, index) :
-      ancestors[index || 0];
+    return Object.isNumber(expression) ? ancestors[expression] :
+      Selector.findElement(ancestors, expression, index);
   },
   
   down: function(element, expression, index) {
     element = $(element);
     if (arguments.length == 1) return element.firstDescendant();
-    var descendants = element.descendants();
-    return expression ? Selector.findElement(descendants, expression, index) :
-      descendants[index || 0];
+    return Object.isNumber(expression) ? element.descendants()[expression] :
+      element.select(expression)[index || 0];
   },
 
   previous: function(element, expression, index) {
     element = $(element);
     if (arguments.length == 1) return $(Selector.handlers.previousElementSibling(element));
     var previousSiblings = element.previousSiblings();
-    return expression ? Selector.findElement(previousSiblings, expression, index) :
-      previousSiblings[index || 0];
+    return Object.isNumber(expression) ? previousSiblings[expression] :
+      Selector.findElement(previousSiblings, expression, index);   
   },
   
   next: function(element, expression, index) {
     element = $(element);
     if (arguments.length == 1) return $(Selector.handlers.nextElementSibling(element));
     var nextSiblings = element.nextSiblings();
-    return expression ? Selector.findElement(nextSiblings, expression, index) :
-      nextSiblings[index || 0];
+    return Object.isNumber(expression) ? nextSiblings[expression] :
+      Selector.findElement(nextSiblings, expression, index);
   },
   
   select: function() {