Modfying a sentence

I want to change some words to another, for example I want to change all "human" words to "animal"... How I will do that?

<?php

$sentence = "human, human, human... One problem with the term is that it implies that human advancement...";

/* ... */

print $modified; // It will show "animal, animal, animal... One problem with the term is that it implies that animal advancement..."

?>

PHP:

 

$sentence = "human, human, human... One problem with the term is that it implies that human advancement...";
$modified = str_replace('human','animal',$sentence);
print $modified;

PHP:

 

Hurray! Thanks