Why Pumpkins are Orange


Julia Paretti and Derek Rinaldi     


CU Boulder, Fall 2006


         Mice, as well as other animals, are attracted to pumpkins and utilize them as a food source. While obtaining necessary resources for their own growth and reproduction, mice inadvertently aid in seed dispersal, pumpkin germination, and subsequent generations. We believe that pumpkins are orange in color to attract animals as seed dispersal mechanisms and facilitate future offspring.  We hypothesize that if mice are more attracted to orange pumpkins than other colored pumpkins, then orange pumpkins will be visited more frequently than pumpkins of other colors.

         To test this hypothesis, we obtained four mice and five pumpkins.  The 5 pumpkins were orange, green, brown, white and yellow.  Each mouse was allowed to acclimate to the study environment, a  white cardboard box,  for 15 minutes before the time of the experiment. The five pumpkins were arranged in a row and the mouse was released in front of them, allowing the mouse to decide which pumpkin was most appealing. For each trial, the pumpkin the mouse visited first was recorded. 5 trials were ran per mouse (20 trials total). The order of pumpkins was changed for each trial so the mice would not become conditioned to a specific spot in the box.

         Our results indicate that the orange pumpkin was visited significantly more than the other colored pumpkins. The orange pumpkin was visited 10 times.  The yellow pumpkin was visited four times.  The green and brown pumpkins were both visited three times, and the white pumpkin was not visited at all.  To test whether our results were statistically significant, we ran a X2 test.  We expected that the orange pumpkin would be visited 16 times, and each of the other colored pumpkin one time each, out of error from each mouse.  If our data was not significant with our expected predictions, then our X2 calc would be larger then our X2 tab.  Our X2 calc was 20.25 and our X2 tab was 21, showing that our results were significant.

         Our results are consistent with our prediction that pumpkins are orange because this is the most appealing color to mice, which may subsequently aid in seed dispersal.  The mice chose the orange pumpkin over twice as many times as any other color, demonstrating its appeal to be consumed first.  We did not encounter any problems with our experiment, although it was noted that the white pumpkin was not visited during any of our trials. We believe that the white pumpkin was not chosen because it had a negative quality that discouraged the mice from choosing it.  To test whether this quality is due to color we could repeat the same experiment, but this time use only white pumpkins to see whether the initial white pumpkin had a strange scent, or something else that prevented the mice from visiting it.  If a white pumpkin is not chosen again, it is possible to conclude that the white pumpkin resembles something inedible to the mice.