NOVA

The Great Inca Rebellion

Student Handout

Bones: Growth Arrest Lines


Diagram of X-ray Growth arrest lines, also known as Harris lines, show up on X-rays of long bones as traverse lines (i.e. perpendicular to the long axis of the bone). They mark points at which the bone's growth was resumed after it had stopped; normally long bones grow continually through childhood until the ends fuse. But when the child is malnourished and the body does not have enough nutrients to go around, bones stop growing. When the crisis is over bone starts to grow again. A line forms as the bone starts to lay down mineral material again. Therefore, growth arrest lines point to short episodes of malnutrition—caused either by infection, poor diet, or starvation—followed by better conditions. An individual who is chronically ill or malnourished would probably have fewer lines than someone who suffered repeated short episodes of disease or starvation. Table 1 shows the number of growth arrest lines seen on the tibias of the members of the two populations.

The Indian Knoll community relied on hunting meat and gathering fruits and nuts and other edible plants. If the Indian Knollers couldn't find food in the winter, they likely suffered seasonal food shortages. The Hardin Village community raised corn and other agricultural crops and supplemented these products with meat. Because agricultural products could be stored, the Hardin Villagers were more likely to have a regular supply of food year-round.

Procedure

  1. Review and graph the data.

  2. Analyze the data for what it reveals about the health of each community.

  3. Use the information on this page and what you have learned from the data to answer the questions listed.


Table 1: Growth Arrest Lines

 

Indian
Knoll

Hardin
Village

Average number growth arrest lines in lower leg bone (tibia)*

11.3

4.1

* Ages and sexes are combined.


Questions
Write your answers on a separate sheet of paper.

  1. The skeletons in both groups show growth arrest lines. What, if any, differences are there between the occurrences of these lines in the two populations?

  2. What conclusions could you draw from this data and the information you have been given?

  3. Write down any other observations you have about this data set.



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