Despite being somewhat of a goof, Miles is an adventurous, selfless man who is willing to go through danger to help others.
Miles is a doctor/scientist in anthropology, which is the study of humanity. According to him, his project in San Lorenzo involved studying the local culture and helping communities improve the quality of their lives. Given this, it can be inferred that he has a social/cultural background in Anthropology.
Miles is shown to be somewhat clumsy and prone to getting injured frequently (similar to Eugene, but less extreme).
Miles has blond hair like his mother and his son, and his chin is very similar to that of his father, though much less pronounced. He usually wears an explorer's outfit. In The Jungle Movie, which is his current appearance, Miles has grey streaks in his hair as a sign of aging. Other than that, he looks very much like he did 10 years ago.
Miles is the only son of Phil and Gertie Shortman, and is Arnold's father. Much like his father, Miles grew up in the Sunset Arms. As a child, Miles had a pet snake named Larry. Miles is a scientist/doctor who visited remote parts of the world, along with his friend Eduardo, to help people who didn't have access to medical help. He didn't have much of a love life, as he felt that no woman would put up with all of the travel he had to go through, until he met someone who not only put up with travel but did quite a bit of it herself — a doctor/botanist named Stella.
Miles and Stella soon became a couple and started exploring together, with the first place being a San Lorenzo temple that was dedicated to "the sacred spider." During a hike up to San Lorenzo's highest point, they both slipped down into a river and fell down a waterfall; only to be caught in a device set up for catching fish. They discovered that the net had been constructed by the mysterious Green Eyed People; the original inhabitants of San Lorenzo.
To pay back the Green Eyes for saving them, Miles and Stella recovered their sacred relic, the Corazón, from the river pirate and treasure hunter, Lasombra. As a reward, Stella and he were accepted as members of the Green Eye family. Shortly afterwards, Miles married Stella in a wedding ceremony at an ancient Mayan temple. Their honeymoon was in Rio de Janeiro in Brazil.
The Green Eyes were then infected with the sleeping sickness and it was up to Miles and Stella to create an antidote for the illness. They were able to do this and saved the Green Eyes just in time.
Soon after, Miles became a father when Arnold was born, and he and Stella decided to go back to Hillwood. However, over a year later, Eduardo returned to ask them for one more mission back in San Lorenzo. Miles and Stella never returned from their mission, and their fates were unknown over the next 9 to 10 years.
In The Jungle Movie, Arnold, Helga, Gerald, and Eduardo find the Green Eyes' city, where they discover that Miles and Stella had caught the sleeping sickness before they could distribute the medicine and return home. Although alive, Miles, Stella, and the other adults in the city can only be awakened with help from the now-lost Corazón. However, when Helga decides to use her locket as a replacement, it works, and Arnold and all of the children reunite with their revived parents.
A few months later, Miles and Stella are revealed to truly be alive and back home with Arnold after he wakes up on the morning of his first day of sixth grade. Shortly after Arnold leaves with his friends, Miles and Stella follow them, asking Arnold if they can walk him to school, to which Arnold agrees. When they arrive, Arnold tells his parents that he'll be done at 3:30. Stella assures him that she and Miles will be waiting on the steps before Arnold smiles at them and the school doors close behind him.