Only having one author post on the home page.

Hi guys

im new to the ‘loop’ and wanted some advise. ive got lots of posts from different authors and so far this pulls up the most recent posts. But i was wondering how i could only have one post per author on the home page?

can anyone guide me in the right directions ?

<?php
$World = new WP_Query(); ?>
<?php $World->query('cat=12,14,102,13,16,18&showposts=5&optioncount=>0'); ?>

<?php while($World->have_posts()) : $World->the_post(); ?>
<ul>
	<li>
   				<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>
				<small>
				Source: <a href="<?php the_syndication_source_link(); ?>"><?php the_syndication_source(); ?></a><br />
                <?php the_time('F jS, Y');?> <br />
				<?php the_tags('Location: '); ?>
               </small>
       </li>
</ul>
<?php endwhile; ?>