Taking the findings of all those papers seriously, suggests that selection could be a huge problem, and that basically one might be able to get whatever result one wanted.
The first paper I am aware of is "Competitiveness Across the Life Span: The Feisty Fifties", Ulrich Mayr, Dave Wozniak, Casey Davidson, David Kuhns, and William T. Harbaugh, Psychology and Aging, 2012 Jun;27(2):278-85.
The abstract reads:
Existing theories on life span changes in confidence or motivation suggest that individuals’ preferences to enter competitive situations should gradually decline with age. We examined competitive preferences in a field experiment using real financial stakes in 25- to 75-year-olds (N=543). The critical dependent variable was whether participants chose to perform a simple mental arithmetic task either under a piece-rate payment schedule (i.e., $.25 per solved item) or a competitive payment schedule ($.50 per solved item if the overall score is better than that of a randomly selected opponent, $0 otherwise). Results revealed that competitive preferences increased across the life span until they peaked around age 50, and dropped thereafter. We also found that throughout, men had a substantially larger preference for competing than women extending previous findings on college-aged participants. The age/gender differences in preferences were neither accounted for by actual differences in performance nor individuals’ subjective confidence. This first systematic attempt to characterize age differences in competitive behavior suggests that a simple decline conception of competitiveness needs to be reconsidered.
The summarizing figure is
The second paper is a new working paper by J. Flory, U. Gneezy, K.Leonard and J. List, "Sex, Competitiveness, and Investment in Offspring: On the Origin of Preferences" comes to very different conclusions (and fails to cite the former paper):
Their abstract reads:
Gender differences in competitive behavior have received much attention, demonstrating a systematic gap between males’ and females’ tendencies to compete. Theories predict a biological factor linked to an evolutionary response to the different paths to reproductive success for men and women. Since strategies for reproductive success change over the female life-cycle, the gender gap is predicted to be largest for young adults but after menopause women should be as competitive as men. Using data drawn from two very different societies, we find strong support for this theoretical prediction: competitiveness in women is tightly linked to their biological roles in childrearing.
Their main figure is
The third paper I know of on age and competitiveness, considers years of work experience instead of age (though the two are highly correlated). It is a paper by Andreas Leibbrandt, Uri Gneezy, and John A. List, "Rise and fall of competitiveness in individualistic and collectivistic societies", PNAS, 2012.
Their abstract reads:
Competitiveness pervades life: plants compete for sunlight and water, animals for territory and food, and humans for mates and income. Herein we investigate human competitiveness with a natural experiment and a set of behavioral experiments. We compare competitiveness in traditional ﬁshing societies where local natural forces determine whether ﬁshermen work in isolation or in collectives. We ﬁnd sharp evidence that ﬁshermen from individualistic societies are far more competitive than ﬁshermen from collectivistic societies, and that this difference emerges with work experience. These ﬁndings suggest that humans can evolve traits to speciﬁc needs, support the idea that socio-ecological factors play a decisive role for individual competitiveness, and provide evidence how individualistic and collectivistic societies shape economic behavior.
Furthermore, they find that for women:
"Women in the individualistic societies who do not ﬁsh were as competitive as women in the collectivistic societies who do not ﬁsh (15% vs. 14.7%, Fisher’s exact test, P = 1, n = 66), suggesting that traits that evolve at work do not easily spread to other society members"
There is strong suggestive evidence that experience and age are highly correlated:
"On average our subjects were 38.2 y (±13.3 SD, n = 289), lived for 28.3 y (±15.8 SD, n=289) in the same ﬁshing society, and had worked for 18.4 y (±12.4 SD, n=289, variable=work experience) professionally as ﬁshermen. In both settings, ﬁshermen work for most of the year, and for 5 to 7 d a week. They are heavily dependent on the shrimp and ﬁsh resources: there are very few other types of jobs in these societies, and ﬁshing is often the only possible"
Of course taking these results, suggests that gender differences in competitiveness can either increase or decrease, it may depend on the work experience of subjects at hand...
Some curious aside:
- Of papers 2 and 3 (that came after paper 1) only paper 2 cites paper 1.
- Papers 2 and 3 do not cite each other...