Difficulty: Advanced 7  
Cost ($): 30  
Time required:
1 hour to prepare, 1 day for the science project experiment 

Availability of materials:
Easily found 

Safety concerns:
None 
Athletes have a higher level of body symmetry.
Body symmetry
Body symmetry means refers to how similar a body's features are, when comparing two identical parts. For example, if the human body were to be "split" in two from the top of the head downwards between the eyes, through the neck all the way down to the chest, through the belly button and finally between the legs, a perfectly symmetrical body would produce two exact mirrorimage sections. Asymmetry is the opposite of symmetry. The aquatic sponge and amoeba are examples of asymmetric organisms. Plants and trees are asymmetric but most leaves and flowers are symmetric. When a person or an animal has lost a limb due to amputation or birth defect, they are referred to as asymmetric.
Although superficially, the human body appears to be very symmetrical, there are quite a few slight variations in our bodies that make us asymmetrical. Growing children will normally display signs of asymmetry that will disappear as they grow older. Aged folks also display asymmetry due to their aging and weakening limbs. This type of asymmetry in the human body is normal.
The materials required for this science fair project:
 5 participants 10 to 15 years old, who are athletic (eg, actively and regularly involved in athletics/sports)
 5 participants 10 to 15 years old, who are not athletic
 1 ruler
 1 caliper
1. For this science fair project, the independent variable is the body part sizes to be compared – 5 fingers, wrist, foot, ear, elbow and knee. The dependent variable is the difference in the sizes of the measured body parts on the left and right sides. This is determined by measuring with the ruler and the caliper. The constants (control variables) are the age group of the participants, and the method of measuring the dimensions of the body parts. If you measure the length of a finger from the tip to the base, use this exact same method to measure the length of each finger, for reliable/meaningful results.
2. The 10 participants were assembled and the following measurements were taken and compared.
a. Thumb  compare the width of the left and right thumb using the caliper
b. Index finger – compare the length of the left and right index finger using the caliper
c. Middle finger – compare the length of the left and right middle finger using the caliper
d. Ring finger – compare the length of the left and right ring finger using the caliper
e. Little finger– compare the length of the left and right little finger using the caliper
f. Wrist – compare the width of the left and right wrist using the caliper
g. Foot – compare the length of the left and right foot using the ruler
h. Ear – compare the length of the left and right ear, from top to bottom, using the caliper
i. Forearm – compare the length of the left and right forearms, from elbow to wrist using the ruler
j. Legs – compare the length of the left and right legs knee to foot using the ruler
3. Comparison of the 10 measurements were made for all 10 participants. If the measurements are identical, it was noted in the table below.
It was observed that the athletes had a higher percentage of symmetry compared to the non athletes. The athletes averaged a 78% body symmetry compared to 70% for the non athletes.
Group  Body symmetry comparisons  Percent  Average  
Thumb  Index  Middle  Ring  Little  Wrist  Foot  Ear  Elbow  Knee  
Athlete 1  Y  Y  Y  Y  Y  Y  X  Y  Y  X  80%  78% 
Athlete 2  Y  Y  Y  Y  Y  X  Y  Y  X  Y  80%  
Athlete 3  Y  Y  Y  Y  Y  X  Y  Y  X  Y  80%  
Athlete 4  Y  Y  Y  Y  Y  X  Y  Y  X  Y  80%  
Athlete 5  X  Y  Y  Y  Y  Y  X  Y  Y  X  70%  
Normal 1  Y  X  Y  Y  X  Y  X  Y  Y  Y  70%  70% 
Normal 2  Y  Y  Y  Y  Y  X  Y  X  X  X  60%  
Normal 3  X  Y  Y  Y  Y  Y  X  X  Y  Y  70%  
Normal 4  Y  Y  X  Y  Y  X  Y  X  Y  Y  70%  
Normal 5  Y  Y  Y  Y  Y  Y  X  Y  X  Y  80% 
Y  symmetrical measurements, X – asymmetric measurements
The hypothesis that athletes have a higher percent of body symmetry, is proven to be true.
Although nature has made our bodies symmetrical, the way we nurture our bodies may result in asymmetry. All of us are either right or left handed, which means we will use one hand more often than the other. The same goes for our legs. Consequently our muscles and limb will tend to grown larger on the dominant side. Certain sports, including racquet games such as tennis, accentuate the asymmetry caused by the use of muscles on one side of the body (eg, in the case tennis, we use only one hand to hold and swing the racquet!) .
Repeat this science fair project comparing the symmetry of bodies among male and female participants?
Modify your science experiment by also comparing the body symmetry of participants from different age groups.
Body symmetry  http://biology.wsc.ma.edu/biology/science fair projects/symmetry/body/
Body symmetry explained  http://www.helium.com/items/448861bodysymmetryexplained
Physical symmetry of human body  http://www.happehtheory.com/HappehTheoryForTheScholar/PhysicalSymmetryOfTheBody/PhysicalSymmetryOfTheHumanBodyMainPage.htm