Show the age at each post

there is a WordPress function that might get close:

http://codex.wordpress.org/Function_Reference/human_time_diff

I figured out that ‘human_time_diff()’ is not suitable, as it stops with ‘days’;

I found a function in the web ( http://www.php.net/manual/en/ref.datetime.php#80866 ) that should do what you want:

http://pastebin.com/wV8rm8Au

add that code to functions.php of your theme.

in your template, whitin the loop, where you want to output the data, add:

<?php
$t1 = get_the_time('M j, Y G:i:s'); //gets the publish date of the post
$t2 = 'Nov 11, 2005'; //this is the reference; i.e. the birthday
echo human_date_diff($t1, $t2, 2); //output the 'age'
?>