SELECT humans.id
         , humans.first_name
         , humans.middle_name
         , humans.last_name
      FROM humans
INNER JOIN ownerships ON ownerships.human_id = humans.id
INNER JOIN pets ON ownerships.pet_id = pets.id
     WHERE pets.name = 'Bo'
  GROUP BY humans.id
         , humans.first_name
         , humans.middle_name
         , humans.last_name
;
 
+----+-------------+------------+--------+---------------+---------+---------+---------------------------+------+---------------------------------+
| id | select_type | table      | type   | possible_keys | key     | key_len | ref                       | rows | Extra                           |
+----+-------------+------------+--------+---------------+---------+---------+---------------------------+------+---------------------------------+
|  1 | SIMPLE      | humans     | ALL    | PRIMARY       | NULL    | NULL    | NULL                      |    9 | Using temporary; Using filesort | 
|  1 | SIMPLE      | ownerships | ref    | PRIMARY       | PRIMARY | 4       | dm_pets.humans.id         |    1 | Using index                     | 
|  1 | SIMPLE      | pets       | eq_ref | PRIMARY       | PRIMARY | 4       | dm_pets.ownerships.pet_id |    1 | Using where                     | 
+----+-------------+------------+--------+---------------+---------+---------+---------------------------+------+---------------------------------+
 
 
SELECT id
     , first_name
     , middle_name
     , last_name
  FROM humans
 WHERE id IN(SELECT DISTINCT human_id FROM ownerships WHERE pet_id IN(SELECT id FROM pets WHERE name = 'Bo'))
;
 
+----+--------------------+------------+-----------------+---------------+---------+---------+------+------+--------------------------+
| id | select_type        | table      | type            | possible_keys | key     | key_len | ref  | rows | Extra                    |
+----+--------------------+------------+-----------------+---------------+---------+---------+------+------+--------------------------+
|  1 | PRIMARY            | humans     | ALL             | NULL          | NULL    | NULL    | NULL |    9 | Using where              | 
|  2 | DEPENDENT SUBQUERY | ownerships | index_subquery  | PRIMARY       | PRIMARY | 4       | func |    1 | Using index; Using where | 
|  3 | DEPENDENT SUBQUERY | pets       | unique_subquery | PRIMARY       | PRIMARY | 4       | func |    1 | Using where              | 
+----+--------------------+------------+-----------------+---------------+---------+---------+------+------+--------------------------+
 
 
    SELECT DISTINCT humans.id
         , humans.first_name
         , humans.middle_name
         , humans.last_name
      FROM humans
INNER JOIN ownerships ON ownerships.human_id = humans.id
INNER JOIN pets ON ownerships.pet_id = pets.id
     WHERE pets.name = 'Bo'
;
 
+----+-------------+------------+--------+---------------+---------+---------+---------------------------+------+-----------------------+
| id | select_type | table      | type   | possible_keys | key     | key_len | ref                       | rows | Extra                 |
+----+-------------+------------+--------+---------------+---------+---------+---------------------------+------+-----------------------+
|  1 | SIMPLE      | humans     | ALL    | PRIMARY       | NULL    | NULL    | NULL                      |    9 | Using temporary       | 
|  1 | SIMPLE      | ownerships | ref    | PRIMARY       | PRIMARY | 4       | dm_pets.humans.id         |    1 | Using index; Distinct | 
|  1 | SIMPLE      | pets       | eq_ref | PRIMARY       | PRIMARY | 4       | dm_pets.ownerships.pet_id |    1 | Using where; Distinct | 
+----+-------------+------------+--------+---------------+---------+---------+---------------------------+------+-----------------------+