Your problem is that the while iterates over each record in turn (setting it to the magical $_), thus you need to set each element of each array in turn, this is done by modifying your code thusly:

$i = -1;
while (<FILE>){  
    chomp;
    $i++;
   ($last[$i], $first[$i], $age[$i], $sex[$i], $height[$i], $weight[$i
+]) = split/,/;
}
die "Sorry, no data\n" if $i == -1;
[download]

Note you do not need the \ before the comma in your split or the parenths. Presume you have no problems with the sort, if not you can use:

@alphabetical = sort @alphabetical

# the above is equivalent to
@alphabetical = sort {$a cmp $b} @alphabetical

@numerical = sort {$a <=> $b} @numerical;

# to reverse the sort order reverse the positions of $a and $b, or use
+ reverse sort @a
[download]

Hope this helps

Cheers

tachyon