“How are your orangutans behaving Lisa?”
It was Anne calling again about her project. I told her my captive orangutans had remained healthy and active the past three years during which I had been collecting the necessary data and forwarding it for analysis to the Center for Reproduction of Endangered Species at the San Diego Zoo.
“Great. I’m sending you a report with the data summarized so far from 13 zoos and a total of 23 males. We’ve measured cortisol and prolactin levels in the urine and made comparisons of hormone levels in four groups of orangutans: juvenile, arrested adolescent, developing adolescent, and adults.”
Below are Anne’s data graphed to show means and standard errors. I’m not sure what it all means.
Figure 1. Urinary cortisol levels expressed as µg of hormone per mg of creatinine in four different groups of captive male orangutans. Asterisks indicate groups significantly different from developing males.
Figure 2. Urinary prolactin levels expressed as ng per mg of creatinine in four different groups of captive male orangutans. Asterisks indicate groups significantly different from developing males.
Data from Maggioncalda, A.M., N.M. Czekala, and R.M. Sapolsky (2002).
Questions
- What are the significant trends in these data? What can you conclude about stress levels in arrested vs. developing males?
- Why did researchers look at prolactin levels? What does prolactin have to do with sexual maturity and stress?
- Why do you think stress hormones are higher in developing males than in arrested or fully mature males?
- According to these data, is stress the explanation for arrested development?
- What other explanations might there be for arrested sexual development in male orangutans?
Originally published at http://www.sciencecases.org/orangutans/case2.asp
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