Scurvy

Discussion Point – Scurvy

This discussion point links to Year 4, 5 and 6 ‘Science’, Year 5 ‘Health and Physical Education’ and General Capabilities Level 4. These curriculum links are listed at the bottom of the page.

The biggest risk to sailors travelling during Cook’s voyage in the 1700s was illness, especially scurvy. Fifty per cent of sailors could be lost to scurvy on a long sea voyage. 

Looking at scurvy and how it was treated in the 1700s provides a historical context for the scientific method.

What is scurvy?

Scurvy is now known to be caused by lack of Vitamin C, or ascorbic acid. Vitamin C is important for many biological processes and making chemicals within the human body. Lack of Vitamin C leads to your biological systems not functioning properly. This is seen by the following symptoms: 

• weakness
• fatigue
• sore arms and legs
• gum disease
• bleeding from the skin
• significant decrease in immune system/ability to heal oneself
• personality changes
• eventual death.

Possible preventative methods

In the 1700s the navy thought that scurvy could be prevented or treated by consuming some of the following things. They did not know why.
• sauerkraut (pickled cabbage; see picture at right)
• portable soup, a soup made from dehydrated meat products (similar to making broth from a stock cube)
• malt (called wort when mixed with water)
• rob of orange and lemon (a form of orange and lemon oil).

Class discussion - Testing possible preventative methods

Class question: How would you test if the methods that the navy thought prevented scurvy actually worked? 

Scientific method:
You could split sailors into groups and get each of the different groups to test a different preventative method. To do this properly, one group of sailors would not be given anything to prevent or treat their scurvy; this is called a control group. A control group is used to compare how well treatments work; if you do not have a control group you do not have a benchmark to measure your success.

Class question: Why would this manner of testing be problematic?

Ethical considerations:
There are significant ethical issues that must be considered when doing testing around health and illness. The sailors in the 1700s were in real danger of dying from scurvy and so all prevention/treatment methods were used. Splitting the sailors into groups for treatment would undoubtedly lead to some of the sailors dying. For ethical reasons Cook had to use every method at his disposal to treat scurvy.

Cook’s approach

Cook was tasked with testing these various methods of preventing scurvy, and he succeeded in preventing the loss of life from scurvy (there were a few cases of scurvy on board, but nobody died). This was further tested in subsequent voyages. Cook tested as many of the current theories for treating and preventing scurvy as he could, including all the methods listed above.

Banks and scurvy

Banks took lemon/lime juice when he noticed that he had the first signs of scurvy. He did this on the recommendation of Dr Hulme (not on board) who had been investigating scurvy treatments. Banks noticed a quick improvement in his symptoms and credited it to the citric fruit juice. 

Cook’s conclusions

There is no way to tell which of the many methods Cook employed actually helped prevent scurvy. He tested too many things at once. In science, the best practice is to test only one variable (changeable element) at a time because it makes the results easier to understand. Otherwise, you can’t work out which variable had an effect, or which treatment helped prevent scurvy.

After Cook’s second voyage he believed that it was the wort that prevented scurvy. In 1776 Cook was awarded the Copley Gold Medal for his work on finding the prevention of scurvy. His belief that wort prevented scurvy was one of the factors that led to wort being one of the most relied upon methods to treat or prevent scurvy. Wort is now known to be ineffective in the treatment of scurvy. 

Problems with treatments

Sauerkraut and citrus juice should have helped prevent scurvy; both cabbages and citrus fruits are high in Vitamin C. However, testing in the 1700s showed these methods to be inconclusive.

Although cabbage and citrus juice should have helped prevent or cure scurvy, they had generally been preserved or cooked so much that they no longer contained high amounts of vitamin C. This was a problem with a lot of historical remedies for scurvy; the ideas behind the treatments were correct but the implementation was wrong.

Explanation of Cook’s success with scurvy

One of easiest ways to prevent scurvy is to eat lots of fresh fruit and vegetables. During his voyage Cook was able to stop for fresh produce at ports along the way. Cook purchased or traded for fresh produce and the naturalists on board searched for edible native plants, e.g. wild celery and scurvy grass (bittercress). This fresh produce would have greatly improved the health of the crew.

Cook also prevented crew members from eating the fat that accumulated at the bottom of the copper cooking pots because he thought it was bad for their general health. We now know that this fat had probably absorbed some of the copper from the pots, which when digested reduced the body’s ability to absorb vitamins and minerals. 

Activity – Scientific Method

Activity – Perfect Planes

Instructions

1. Give every student a piece of paper and ask them to make the best paper plane. 
2. Line up the students and ask them all to throw their paper plane. Mark which paper plane flies the longest, farthest, highest, and if any plane does tricks (or anything else notable).
3. Ask the students which plane is the ‘best’. Discuss what makes the plane the best.

Explanation

When designing a scientific experiment it’s important to define all its different aspects. In this case we did not define the term ‘best’, which is subjective. Each of the students may consider a different plane to be the best.

Extension

4. Can the students remake their plane? Get the students to think about possible variables.

Extension explanation

A key aspect of scientific method is the ability to be repeated and reproduced. It is very unlikely that students would be able to build a second plane that is identical to their first plane.