abstract class human_template {

    /**
     * The humans name
     * @var string
     */
    protected $name;

    /**
     * The human sex
     * @var string
     */
    protected $sex;

    /**
     * The human age
     * @var integer
     */
    protected $age;

    /**
     * Returns the current population of the Human class
     * @return integere
     */
    static $population = 0;

    /**
     * Constructor, also set self::SetPopulation to +1 (human population)
     * @param type $name
     * @param type $age
     */
    function __construct($name, $age) {
        self::SetPopulation();
        $this->name = $name;
        $this->age = $age;
    }

    /**
     * Static function, that adds 1 to the current HUMAN population everytime an object is made fra abstract class
     */
    private static function SetPopulation() {
        human_template::$population++;
    }
}

// end of abstract class human_template

/**
 * Man class based upon human_template abstract
 */
class man extends human_template {

    /**
     * Declares the gender of the human
     * @var string
     */
    protected $sex = 'man';

    /**
     * Declares the current MAN population
     * @var integere
     */
    static $population = 0;

    /**
     * Calls the parent construct from abstract human_class
     * @param type $name
     * @param type $age
     */
    function __construct($name, $age) {
        parent::__construct($name, $age);
        self::$population++;
    }
}

    /**
     * Calls the parent construct from abstract human_class
     * @param type $name
     * @param type $age
     */
class woman extends human_template {

    /**
     * Sets the human gender to woman
     * @var String
     */
    protected $sex = 'woman';

    /**
     * Contains the current generated human womans.
     * @var integer
     */
    static $population = 0;

    /**
     * Calls the parent construct from abstract human_class
     * @param type $name
     * @param type $age
     */
    function __construct($name, $age) {
        parent::__construct($name, $age);
        self::$population++;
    }
}

$human1 = new woman('wendy', '19');
$human2 = new man('jack', '21');

print_r($human1);
print_r($human2);