As described in Hugh Holman's A Handbook to Literature, naturalism is portrayed as man's "endless and brutal struggle for survival" (337-339). Nunn ally Johnson and John Ford's movie The Grapes of Wrath portrays this same "animal nature of man," but also adds to the definition by showing the instinctive nature for people to live rather than die. The struggle of the Joad family through plot shows the animal instinct of man to adapt to continual change during hard times for an individual's survival, the lower working class of society shows through symbolism the need for man to help others for the survival of the whole population, and through the characterization of Ma and Pa shows the heavy emphasis that man puts on children during stressful times to insure the future survival of the whole species. Throughout the movie the plot continually shows the struggles of the Joad family to survive for themselves and their families. From the very beginning of the movie the Joads are forced to move off the land that they have farmed for generations.

Instead of simply giving up because the only life they have known has been taken away from them, the family continues to struggle for their own survival by moving to California. They refuse to give up, and instead opt to adapt to a new life. As the Joads travel to California they pass road signs, showing this same change from living in a rural farm community, to their new lives in California. The Joads also show that they are willing to go to any lengths in order to keep themselves and their family alive. They find work at the second camp they encounter, and despite the horrible living and working conditions, the Joads do not give up and continue to earn money for their family. Their only motivation is to make enough money so that their family will have enough food to eat.

At the end of the movie the Joads show that they are not willing to let others support them, but they feel they are capable to make a living for themselves. The third camp that the Joads run into is well kept, nice, clean, and even has running water, a drastic change from other camps that they have seen. They have the opportunity to stay at this camp even though they are not able to fully support themselves, but they refuse to. Instead, the Joads choose to leave in search of work they are not even sure exists.

They continue on their pursuit to find a good life, and are ready to endure any rough times that may come along the way. All throughout the movie, people of the lower social class symbolize man's efforts to help others in hopes to guarantee their survival. A prime example is when the Joads stop at a store to buy bread. Pa Joad only has 10 cents, and the bread costs 15 cents. After some contemplation, the diner waitress decides to sell him the bread for only 10 cents, and also sells him candy for 2 cents that actually costs 10 cents.

Due to the Depression, everyone was short of money, but the lady still gave the Joads bread and candy even if it meant that she would have to pay up the difference. Ultimately, two truckers, who also don't have a lot of money to spare, give the cashier their extra change to compensate for what the Joads did not pay for to further emphasis the point that people were always sticking together and looking out for one another. Preacher Casey also shows that he is willing to make sacrifices for others during tough times. When Tom gets angry and punches a man, the Preacher tells the police that he is responsible so Tom will not have to suffer the consequence and go to jail. The Preacher proves that he is willing to give up his freedom for the common good. Other people also show willingness to help others during hard times.

When Tom is working in the fields at the third camp, a farmer working with Tom warns him that police are going to stage a fight to try to shut Tom's camp down. The farmer not only saves the Joads, but he also saves the many others who also live at the camp. Although he could get in trouble for passing along this valuable information, he chooses to tell Tom anyway, in order to protect his fellow farmers from possible harm. The lower class of this society symbolize unity, and working towards the survival of an entire population.

Tom Joad speaks on behalf of the working class when he says, "A man doesn't have a soul. He's just a piece of a whole." Through the characters of Ma and Pa the heavy emphasis and the importance put on children to insure the survival or future generations can be clearly seen. Ma puts a lot of importance on Rose Ann Sharon's pregnancy, and often times says things like, "A woman always looks most beautiful when she is pregnant." She feels that the birth of a child is a beautiful thing, and deserves a lot of attention. Ma also puts the needs of children first when she is at the first camp. Ma decides to feed all the hungry children at the camp even though there is not even enough food for her own family.

Ma shows that she has a lot of love, and sees a lot of value in the children because they will ultimately go on to shape her future. Pa also shows a great importance for children when he chooses to buy the two children of the family candy at a diner even though he is well aware that the family can't afford it. Pa wants to make sure that all the children are happy, and then only can he be satisfied to move on in his journey. Throughout the movie The Grapes of Wrath, using the different literary elements, the movie shows the different forms of survival including the Joad's constant struggle for the survival of an individual, the lower class of society symbolizing the survival of an entire population, and Ma and Pa's characters representing the survival of the future, all dealing with the survival of an entire species. The movie is based on the instinct of all animals to survive despite falling " victim [to] forces beyond [its] control" (Holman 337-339).