INTRODUCTION Take a look at your right-hand. Which finger is longer, your ring finger or your index finger? Generally, a greater portion of men have shorter index fingers than ring fingers compared to women. Wilson (1975) published a study examining the correlation between digit ratios. This is the ratio of lengths of different digits, fingers or toes, typically as measured from the bottom crease where the finger joins the hand to the tip of the finger. Wilson’s study was the first study to examine the correlation between digit ratio and a psychological trait within members of the same sex.The Hox gene family is required for the growth and patterning of digits and the differentiation of the genital bud. In humans anatomical defects in digits and genitalia occur in the hand-foot-genital syndrome which results from a mutation within Hoxa. These observations raise the possibility that patterns of digit growth may be related to fertility. The common control of digit differentiation raises the possibility that patters of digit formation may relate to spermatogenesis and hormonal concentrations. Surprisingly there is a lot that you can tell about a person from their finger length. John T. Manning (2002) reviews evidence to suggest that the length between the ring and index finger is somewhat sexually dimorphic, meaning the ratio is determined during early fetal development, and is influenced by sex hormones, particularly testosterone. Females typically have index and ring fingers of about the same length. According to Manning higher levels of testosterone during a critical fetal development stage (later part of the first trimester) facilitates the growth of the ring finger, while higher levels of estrogen facilitates the growth of the index finger. Some characteristics of Manning’s research suggest, if females are introduced to more testosterone they have a greater possibility of becoming bisexual, more masculinized, and are more aggressive and assertive. If they are introduced to more estrogen they are more fertile, have higher lifetime reproductive success, and a higher risk of breast cancer. Why is there any overlap between the sexes in sexually dimorphic traits in the first place, including digit ratio? Manning (2002) interprets this as an evolutionary stable equilibrium point in a conflict between sexually antagonistic genes. Genes that tend to masculinize the fetus will increase when there is an advantage to having male offspring. The benefits of more masculinized male fetuses will compensate for the reduced fertility of female offspring due to their relatively higher than normal fetal exposure to male hormones.Manning (2002) notes that a longer ring finger may help stabilize the middle finger when throwing objects, this would increase throwing accuracy. So in turn this would give them more of an advantage in sporting activities. The length of a girl’s ring finger could be an early indicator of her future sporting potential. It was also found in a separate study of twins that finger length was largely inherited, possibly explaining why sporting parents often have sporting children. According to Professor Tim Spector (2006) from the Twins Research Unit at King’s College, “we have found that finger length was 70 percent heritable with little influence of the womb environment.” He said that no specific candidate genes had been identified for the link and that multiple genes were probably responsible.After understanding the causes and effects of digit ratio I would like to try and see if I can find any supporting evidence linked to athletic ability in females. The purpose of the study is to try and find a relationship in finger length with female athletes at Missouri Western State University.
The participants that I used in this study (Finger Length Linked to Female Athletic Ability), are undergraduate students at Missouri Western State University. Missouri Western State University is a medium sized university in western Missouri. This experiment was performed on 28 female athlete participants from the women’s volleyball, soccer, and softball teams, and 36 female psychology 101 students.
Used to complete this study is a ruler and two sheets of paper. The ruler was a Wescott finger grip 12” aluminum ruler, made by Acme United Corporation. One of the sheets of paper is labeled at the top, “Missouri Western State University female athletes,” and the other is labeled, “Missouri Western State University psychology 101 female students.” These sheets are divided into five categories, the first listing subjects 1-40, the second is a section to record the length of the female’s right handed index finger, the third is a section to record the length of the female’s right handed ring finger, forth is to record the length of the female’s left handed index finger, and the fifth is to record the length of the female’s left handed ring finger.
To begin the study I met with the Missouri Western State University women’s volleyball, soccer and softball teams in the volleyball locker room of the Looney Complex. I asked them to just randomly volunteer to have their fingers measured until everyone in the room has gone. I also asked them when they approach me to have their fingers measured not to identify any information about who they are, except that they are an athlete at Missouri Western State University. For each person the procedure was exactly the same. I will ask them for their right- handed index finger and measure it from the crease at the bottom to the top with a ruler. Then I asked to do the same with the right handed- ring finger, followed by the left- handed index finger, and then the left- handed ring finger. After all the measurements are completed I offered cookies to thank them for helping with my study. As for the psychology 101 students, I met them in there classroom, I informed them that I will be measuring their index and ring fingers on both hands, and that they will not have to reveal their name or any other information about themselves besides their finger length. I told them they have the choice of whether they would like to participate in my study or not, and if they choose to do so, after I measure their fingers they can have a cookie. After I informed them of this, I asked them to just randomly one-by-one come to me to have their fingers measured. For each of them the procedure was exactly the same as the athletes. I asked them for their right-handed index finger and measured it from the crease at the bottom to the top, then measured their right-handed ring finger, followed by measuring their left-handed index finger, and then measuring their left-handed ring finger. When I completed the individuals finger measurement, I allowed them to take a cookie and return back to their seat. This procedure was repeated until every female in the room that wanted to go has gone.
RESULTS An independent-samples t test was calculated comparing the average ratio of right hand index to ring finger mean ratio of people who are Missouri Western State University psychology 101 students to the mean ratio of Missouri Western State University athletes. No significant difference was found (t(62)= .615, p= .541). The mean of the psychology 101 students (m = 99.84, sd = 4.91) was not significantly different from the mean of the athletes (m = 99.13, sd = 4.104). Results can be seen in Figure 1.An independent-samples t test comparing the average ratio of left hand index to ring finger mean ratio of people who are Missouri Western State University psychology 101 students to the mean ratio of Missouri Western State University athletes found a significant difference between the means of the two groups (t(62) = 2.687, p < .01). The mean of the psychology 101 students was significantly higher (m = 101.63, sd = 5.914) than the mean of the athletes (m = 98.08, sd = 4.231). Indicating that athletes left ring fingers are longer than their index fingers. Results can be seen in Figure 1.
DISCUSSION The results of the experiment were mostly conclusive with our hypothesis when you refer to the left hand. When referring the right hand the results were not consistent with our hypothesis. In this study we wanted to know if there was a relationship with digit ratio and athletic ability. Manning (2002) stated that finger length was sexually dimorphic and that higher levels of testosterone facilitate the growth of the ring finger. As far as I know Manning did not state in his studies whether it was both ring fingers that had to be longer than the index, or if it could be one index finger and not the other. So this experiment could be consistent with Manning if he believes that it could be one ring finger or the other that is longer then the index, but not if it refers to both ring fingers being longer than the index. Tim Spector (2006) states that we have a 70 percent heritable finger length and that there is little womb influence. Without further studies done, there is no way of knowing whether this experiment is consistent with Spector or not. In the future I believe that it would be very interesting to measure athlete’s parent’s finger length also to see if there is a correlation. When doing this study again I would try to find a larger sample of athletes and non-athletes to use. Also I would recruit athletes that are at a higher competitive level to participate in the study, to assure that I am getting genuine athletes. Another thing that I would change would be the way of measuring the finger length, in this study I used a ruler to measure the finger length, in the future I believe that results would be more accurate if each individuals hand would be copied using something such as a copy machine. That way you have the finger length on file, and there would be no room for experimenter bias. When using the ruler it would be very easy for the experimenter to not place the ruler in the exact same spot when measuring each finger. The measurements will probably be more accurate if the copies were given to someone else for measurement, that does not know whether they are measuring athletes or non- athletes. It also allows other researchers to use your data to add to theirs help make a larger sample size, as long as you have consent of the participant.Another interesting way of conducting this study would be next time to measure the different sports separately. If you do it this way you can look at many more different angles of the results. You can evaluate whether finger length is different or the same in sports that require a lot of running compared to sports that don’t. Or if sports that require more strength such as body building would have different results. Mainly just to see if there is any one sport that has more differences in digit ratios than the others.
REFERENCES Bem, S. (1974) The measurement of psychological androgyny. Journal of consulting and Clinical Psychology, 42, 155-162.Digit Ratio. Wikipedia, the free encyclopedia. Retrieved October 23, 2006, from http://en.wikipedia.org/wiki/Digit_ratioFinger length linked to female sporting potential. Reuters. Retrieved September 28, 2006, from http://today.reuters.com/news/articlenews.aspx?type=oddlyEnoughNews&storyid =2006-09-28T115355Z_01_L27398086_RTRUKOC_0_US-FINGER1.xmlManning, J.T., Scott, D., Wilson, J., & Lewis-Jones, D.I. (1998). The ratio of the 2nd to 4th digit length: A predictor of sperm numbers and concentration of testosterone, luteinizing hormone and oestrogen. Human Reproduction, 13, 3000-3004.Mills, M. (Oct2002). Digit Ratio: A Pointer to Fertility, Behavior and Health. Human Nature Review, 2, 418-423.