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Robert Deaner

Grand Valley State University, Psychology, Faculty Member

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My goal is to contribute to a scientific understanding of human nature, especially by demonstrating the value of evolutionary theory. Most of my current projects involve sex differences, sports, and the limitations of Blank Slate conceptions of human nature.

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Papers by Robert Deaner

Missed Connections Integrating Proximate and Ultimate Explanations in Cognitive Neuroscience

ORIGINAL PAPER Distance Running as an Ideal Domain for Showing a Sex Difference

Men are over-represented in the arts, sciences, and sports. This has been hypothesized to reflect... more Men are over-represented in the arts, sciences, and sports. This has been hypothesized to reflect an evolved male predisposition for enduring competitiveness or long-term moti-vation to improve one’s performance and‘‘show-off.’’Evidence for thishypothesis isequivocal,however,because thereareviable alternative explanations for men’s dominance in most cultural display domains. Here, I argue that distance running is an ideal domain for addressing this issue. Distance running is ideal because it indicates enduring competitiveness, allows objective comparisons, and is accessible, acceptable, and popular for both men and women. I review recent studies and present new data showing that substantially more men than women run relatively fast in theU.S., that thissexdifferenceinrelativeperformancecan be attributed, at least in part, to men’s greater training motivation, and that this pattern has been stable for several decades. Distance running thus provides compelling evidence for an evolved ...

A sex difference in the predisposition for physical competition: Males play sports much more than females even in the contemporary US. PLoS One 2012

Much evidence indicates that men experienced an evolutionary history of physical competition, bot... more Much evidence indicates that men experienced an evolutionary history of physical competition, both one-on-one and in coalitions. We thus hypothesized that, compared to girls and women, boys and men will possess a greater motivational predisposition to be interested in sports, especially team sports. According to most scholars, advocacy groups, and the United States courts, however, this hypothesis is challenged by modest sex differences in organized school sports participation in the contemporary U.S., where females comprise 42 % of high school participants and 43 % of intercollegiate participants. We conducted three studies to test whether organized school sports participation data underestimate the actual sex difference in sports participation. Study 1 analyzed the American Time Use Survey, which interviewed 112,000 individuals regarding their activities during one day. Females accounted for 51 % of exercise (i.e., non-competitive) participations, 24 % of total sports participatio...

Cross-Cultural Research Sex Differences in Sports Across 50 Societies On behalf of: Society for Cross-Cultural Research

Sex differences in exclusion and aggression on single-sex sports teams

Evolutionary Behavioral Sciences, 2020

Sex differences in the use of competitive tactics have been well documented and may reflect evolv... more Sex differences in the use of competitive tactics have been well documented and may reflect evolved predispositions. Recent research, however, suggests these differences may be eliminated in single-sex environments. We addressed this possibility by surveying men and women about their recent experiences as members of college (n = 376) and high school (n = 485) single-sex sports teams. We focused on participants’ recollections of being targets of exclusion or overt aggression by their teammates. In both samples, women were significantly more likely than men to recall being excluded (college Odds Ratio [OR] = 2.88; high school OR = 1.67) and receiving overt verbal aggression (ORs = 9.15, 3.30). By contrast, women were significantly less likely than men to recall receiving overt physical aggression (ORs = 0.18, 0.14). Furthermore, as predicted by the male warrior hypothesis, compared to men, women were more likely to be excluded by (ORs = 4.2, 3.36) or to receive aggression from (ORs = 13.69, 3.61) teammates in a competitive context (i.e., game) compared to other contexts. This pattern was significant for aggression in both samples and for exclusion in the high school sample. Collectively, these results indicate that differences in the behavior of men and women persist in single-sex settings where groups must cooperate against opponents.

Born to Throw: The Ecological Causes that Shaped the Evolution of Throwing In Humans

The Quarterly Review of Biology, 2018

Humans are the only species capable of powerful and accurate overhand throwing. However, the evol... more Humans are the only species capable of powerful and accurate overhand throwing. However, the evolution of this ability remains underexplored. Here we draw on several lines of evidence—anatomical, archeological, cross-species comparisons, and ethnographic—to develop a scenario for the evolution of throwing. Throwing has deep roots in the primate lineage. Nonhuman primates throw projectiles during agonistic interactions but rarely to subdue prey. Thus, we argue that throwing first arose during agonistic interactions and was later incorporated into hunting by human ancestors. The fossil record indicates that anatomical adaptations for high-speed throwing in Homo first appeared about two million years ago. Once the effective use of projectile weapons became critical to success in combat and hunting, the importance of the ability to throw, intercept, and dodge projectiles would have resulted in stronger selection on males than females to become proficient at these skills because males throw projectiles more often than females in both combat and hunting.

On The Evolution of The Sex Differences in Throwing: Throwing is a Male Adaptation in Humans

The Quarterly Review of Biology, 2018

The development of the ability to throw projectiles for distance, speed, and accuracy was a water... more The development of the ability to throw projectiles for distance, speed, and accuracy was a watershed event in human evolution. We hypothesize that throwing first arose in threat displays and during fighting and later was incorporated into hunting by members of the Homo lineage because nonhuman primates often throw projectiles during agonistic interactions and only rarely in attempts to subdue prey. Males, who threw more often than females in both combat and hunting, would have been under stronger selection than females to become proficient at the ability to throw, intercept, and dodge projectiles as throwing skills became critical to success in combat and hunting. Therefore, we predict that males, more than females, should display innate anatomical and behavioral traits associated with throwing. We use data from a variety of disciplines to discuss: the sex differences in throwing speed, distance, and accuracy; sex differences in the development of the throwing motion; inability of training or cultural influences to erase the sex differences in throwing; sex differences in the use of throwing in sports, combat, and hunting; and sex differences in anatomical traits associated with throwing that are partly responsible for male throwing superiority. These data contradict the view held by many commentators that socialization rather than innate sex differences in ability are primarily responsible for male throwing superiority. We suggest that throwing is a male adaptation.

Risk Taking Runners Slow More in the Marathon

Frontiers in Psychology, 2019

Gender equality predicts leisure-time physical activity: Benefits for both sexes across 34 countries

Cogent Psychology, 2016

Although countries' gender equality is associated with important health outcomes, especially for ... more Although countries' gender equality is associated with important health outcomes, especially for females, it remains unclear whether gender equality is associated with leisure-time physical activity (LTPA). Data from 34 countries was acquired from the International Social Survey Program, the Pew Research Forum, the United Nations, and the World Bank. Separate analyses were conducted for 21,502 males and 26,652 females. Hierarchal nonlinear Bernoulli modeling was used to examine the association between gender equality and participation in LTPA. Both males and females residing in countries' with higher gender equality were more likely (twice and three times more likely, respectively) to report weekly LTPA than those residing in countries characterized by low gender equality. These effects persisted even when controlling for individual (i.e. age, education) and country-level (i.e. population, gross domestic product) covariates. However, significant variation in LTPA persisted at the country level, suggesting the need for further research. These findings provide novel evidence that both males and females benefit from gender equality. To explain these findings, we hypothesize that increased gender equality decreases the average number of offspring and, in turn, allows mothers more time for leisure, and to invest more resources in both male and female offspring, which may increase LTPA.

Further questions about dehumanization

Journal of Social, Evolutionary, and Cultural Psychology, 2012

It was still late August when one day the door to the Spanish House was flung open, and the two s... more It was still late August when one day the door to the Spanish House was flung open, and the two spinsters were forced to kneel in front of it. Dragged from her wheelchair, the old mother was forced to join them, but she was so feeble that she collapsed into a heap on the terrace. The mob yelled and screamed, banging their fists on every available surface. The old women were called “bloodsucking leeches,”“maggots,” and “intestinal parasites.”

Misrepresentations of Evolutionary Psychology in Sex and Gender Textbooks

Evolutionary Psychology, 2014

Evolutionary psychology has provoked controversy, especially when applied to human sex difference... more Evolutionary psychology has provoked controversy, especially when applied to human sex differences. We hypothesize that this is partly due to misunderstandings of evolutionary psychology that are perpetuated by undergraduate sex and gender textbooks. As an initial test of this hypothesis, we develop a catalog of eight types of errors and document their occurrence in 15 widely used sex and gender textbooks. Consistent with our hypothesis, of the 12 textbooks that discussed evolutionary psychology, all contained at least one error, and the median number of errors was five. The most common types of errors were “Straw Man,” “Biological Determinism,” and “Species Selection.” We conclude by suggesting improvements to undergraduate sex and gender textbooks.

Distance Running as an Ideal Domain for Demonstrating a Sex Difference in Enduring Competitiveness

SSRN Electronic Journal, 2011

Abstract: Men's dominance of cultural displays has been hypothesized to reflect an evolved m... more Abstract: Men's dominance of cultural displays has been hypothesized to reflect an evolved male predisposition for enduring competitiveness. Evidence for this hypothesis is equivocal, however, because there are viable alternative explanations for men's dominance in most display domains. Here I argue that distance running is an ideal domain for addressing this issue. Distance running is ideal because it indicates enduring competitiveness, allows objective comparisons, and is accessible, acceptable, and popular for both men and ...

Book Review: A Big Batch of Mismatch

Evolutionary Psychology, 2014

Most readers of this journal believe that many aspects of our psychology and biology are mismatch... more Most readers of this journal believe that many aspects of our psychology and biology are mismatched to the modern environments we currently inhabit. The standard example is that we have persistent cravings for sugar, salt, fat, and starch because they served us well when we were hunter-gatherers, but these cravings often lead to grave health problems in post-industrial societies. The mismatch perspective is pervasive, even central, to the fields of evolutionary psychology and evolutionary medicine. In fact, every year brings several new books on the topic. Thus, when we learn that a leading evolutionary anatomist, Daniel Lieberman, has written another mismatch book, The Story of the Human Body, two questions arise: First, does his perspective agree with ours, i.e., that mismatches are vitally important? Second, will his background allow him to teach us something new? The answers are emphatically "Yes" and "Yes." Perhaps the book's greatest contribution is its detailed treatment of various health-related mismatches and explanations of how the cultural solutions often produce unintended effects that exacerbate the underlying problems, a process Lieberman calls "dysevolution." Lieberman's book has three parts. Part I, "Apes and Humans," sets the stage, covering everything from our last common ancestor with chimpanzees and gorillas, roughly 8 million years ago, until the end of the paleolithic about 10,000 years ago. It's the story of human evolution in 150 pages, explicating and unifying topics as diverse as recent fossil discoveries (e.g., "Hobbit of Flores"), Lieberman's own groundbreaking work on adaptations for bipedal walking and running, and the evidence bearing on hominid foraging, life history, activity patterns, energetics, and culture. If you never took a topquality human evolution class, Part I will do the job. If you have taken such a course, then this section will get you up to speed on the latest discoveries.

U.S. Masters Track Participation Reveals a Stable Sex Difference in Competitiveness

Evolutionary Psychology, 2014

It is well established that men are more likely than women to engage in direct competition, but i... more It is well established that men are more likely than women to engage in direct competition, but it is unclear if this reflects social structural conditions or evolved predispositions. These hypotheses can be addressed by quantifying competitiveness in sports and testing if the sex difference is decreasing over time in the U.S., a society where social roles have converged. Study 1 assessed participation and the occurrence of relatively fast performances by masters runners (40–74 years old) at recent road races and track meets. Fast performances occurred over 20 times more often at track meets than at road races. Women comprised 55% of finishers at roads races but only 15–28% of finishers at track meets. Thus, the sex difference in masters track participation can serve as a measure of the sex difference in competitiveness. Study 2 used data from national championship meets and yearly rankings lists to test whether the sex difference in masters track participation decreased from 1988–2...

A big batch of mismatch: A review of Daniel E. Lieberman, The Story of the Human Body: Evolution, Health, and Disease

Does the sex difference in competitiveness decrease in selective sub-populations? A test with intercollegiate distance runners

PeerJ, 2015

You can't teach speed: sprinters falsify the deliberate practice model of expertise

PeerJ, 2014

Many scientists agree that expertise requires both innate talent and proper training. Nevertheles... more Many scientists agree that expertise requires both innate talent and proper training. Nevertheless, the highly influential deliberate practice model (DPM) of expertise holds that talent does not exist or makes a negligible contribution to performance. It predicts that initial performance will be unrelated to achieving expertise and that 10 years of deliberate practice is necessary. We tested these predictions in the domain of sprinting. In Studies 1 and 2 we reviewed biographies of 15 Olympic champions and the 20 fastest American men in U.S. history. In all documented cases, sprinters were exceptional prior to initiating training, and most reached world class status rapidly (Study 1 median = 3 years; Study 2 = 7.5). In Study 3 we surveyed U.S. national collegiate championships qualifiers in sprinters (n = 20) and throwers (n = 44). Sprinters recalled being faster as youths than did throwers, whereas throwers recalled greater strength and throwing ability. Sprinters' best perform...

Throwing out the mismatch baby with the paleo-bathwater: A review of Marlene Zuk, Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live

Born at the Wrong Time: Selection Bias in the NHL Draft

Relative age effects (RAEs) occur when those who are relatively older for their age group are mor... more Relative age effects (RAEs) occur when those who are relatively older for their age group are more likely to succeed. RAEs occur reliably in some educational and athletic contexts, yet the causal mechanisms remain unclear. Here we provide the first direct test of one mechanism, selection bias, which can be defined as evaluators granting fewer opportunities to relatively younger individuals than is warranted by their latent ability. Because RAEs are well-established in hockey, we analyzed National Hockey League (NHL) drafts from 1980 to 2006. Compared to those born in the first quarter (i.e., January-March), those born in the third and fourth quarters were drafted more than 40 slots later than their productivity warranted, and they were roughly twice as likely to reach career benchmarks, such as 400 games played or 200 points scored. This selection bias in drafting did not decrease over time, apparently continues to occur, and reduces the playing opportunities of relatively younger players. This bias is remarkable because it is exhibited by professional decision makers evaluating adults in a context where RAEs have been widely publicized. Thus, selection bias based on relative age may be pervasive.

Men are More Likely than Women to Slow in the Marathon

Medicine and science in sports and exercise, Jan 9, 2014

Studies of non-elite distance runners suggest that men are more likely than women to slow their p... more Studies of non-elite distance runners suggest that men are more likely than women to slow their pace in the marathon. This study determined the reliability of the sex difference in pacing across many marathons, and after adjusting women's performances by 12% to address men's greater maximal oxygen uptake and also incorporating information on racing experience. Data was acquired from 14 U.S. marathons in 2011, and encompassed 91,929 performances. For 2,929 runners, we obtained experience data from a race-aggregating website. We operationalized pace maintenance as percentage change in pace observed in the second half of the marathon relative to the first half. Pace maintenance was analyzed as a continuous variable and as two categorical variables: "maintain the pace," defined as slowing < 10%; and "marked slowing," defined as slowing ≥30%. The mean change in pace was 15.6% and 11.7% for men and women, respectively (P<0.0001). This sex difference was s...

Missed Connections Integrating Proximate and Ultimate Explanations in Cognitive Neuroscience

ORIGINAL PAPER Distance Running as an Ideal Domain for Showing a Sex Difference

Men are over-represented in the arts, sciences, and sports. This has been hypothesized to reflect... more Men are over-represented in the arts, sciences, and sports. This has been hypothesized to reflect an evolved male predisposition for enduring competitiveness or long-term moti-vation to improve one’s performance and‘‘show-off.’’Evidence for thishypothesis isequivocal,however,because thereareviable alternative explanations for men’s dominance in most cultural display domains. Here, I argue that distance running is an ideal domain for addressing this issue. Distance running is ideal because it indicates enduring competitiveness, allows objective comparisons, and is accessible, acceptable, and popular for both men and women. I review recent studies and present new data showing that substantially more men than women run relatively fast in theU.S., that thissexdifferenceinrelativeperformancecan be attributed, at least in part, to men’s greater training motivation, and that this pattern has been stable for several decades. Distance running thus provides compelling evidence for an evolved ...

A sex difference in the predisposition for physical competition: Males play sports much more than females even in the contemporary US. PLoS One 2012

Much evidence indicates that men experienced an evolutionary history of physical competition, bot... more Much evidence indicates that men experienced an evolutionary history of physical competition, both one-on-one and in coalitions. We thus hypothesized that, compared to girls and women, boys and men will possess a greater motivational predisposition to be interested in sports, especially team sports. According to most scholars, advocacy groups, and the United States courts, however, this hypothesis is challenged by modest sex differences in organized school sports participation in the contemporary U.S., where females comprise 42 % of high school participants and 43 % of intercollegiate participants. We conducted three studies to test whether organized school sports participation data underestimate the actual sex difference in sports participation. Study 1 analyzed the American Time Use Survey, which interviewed 112,000 individuals regarding their activities during one day. Females accounted for 51 % of exercise (i.e., non-competitive) participations, 24 % of total sports participatio...

Cross-Cultural Research Sex Differences in Sports Across 50 Societies On behalf of: Society for Cross-Cultural Research

Sex differences in exclusion and aggression on single-sex sports teams

Evolutionary Behavioral Sciences, 2020

Sex differences in the use of competitive tactics have been well documented and may reflect evolv... more Sex differences in the use of competitive tactics have been well documented and may reflect evolved predispositions. Recent research, however, suggests these differences may be eliminated in single-sex environments. We addressed this possibility by surveying men and women about their recent experiences as members of college (n = 376) and high school (n = 485) single-sex sports teams. We focused on participants’ recollections of being targets of exclusion or overt aggression by their teammates. In both samples, women were significantly more likely than men to recall being excluded (college Odds Ratio [OR] = 2.88; high school OR = 1.67) and receiving overt verbal aggression (ORs = 9.15, 3.30). By contrast, women were significantly less likely than men to recall receiving overt physical aggression (ORs = 0.18, 0.14). Furthermore, as predicted by the male warrior hypothesis, compared to men, women were more likely to be excluded by (ORs = 4.2, 3.36) or to receive aggression from (ORs = 13.69, 3.61) teammates in a competitive context (i.e., game) compared to other contexts. This pattern was significant for aggression in both samples and for exclusion in the high school sample. Collectively, these results indicate that differences in the behavior of men and women persist in single-sex settings where groups must cooperate against opponents.

Born to Throw: The Ecological Causes that Shaped the Evolution of Throwing In Humans

The Quarterly Review of Biology, 2018

Humans are the only species capable of powerful and accurate overhand throwing. However, the evol... more Humans are the only species capable of powerful and accurate overhand throwing. However, the evolution of this ability remains underexplored. Here we draw on several lines of evidence—anatomical, archeological, cross-species comparisons, and ethnographic—to develop a scenario for the evolution of throwing. Throwing has deep roots in the primate lineage. Nonhuman primates throw projectiles during agonistic interactions but rarely to subdue prey. Thus, we argue that throwing first arose during agonistic interactions and was later incorporated into hunting by human ancestors. The fossil record indicates that anatomical adaptations for high-speed throwing in Homo first appeared about two million years ago. Once the effective use of projectile weapons became critical to success in combat and hunting, the importance of the ability to throw, intercept, and dodge projectiles would have resulted in stronger selection on males than females to become proficient at these skills because males throw projectiles more often than females in both combat and hunting.

On The Evolution of The Sex Differences in Throwing: Throwing is a Male Adaptation in Humans

The Quarterly Review of Biology, 2018

The development of the ability to throw projectiles for distance, speed, and accuracy was a water... more The development of the ability to throw projectiles for distance, speed, and accuracy was a watershed event in human evolution. We hypothesize that throwing first arose in threat displays and during fighting and later was incorporated into hunting by members of the Homo lineage because nonhuman primates often throw projectiles during agonistic interactions and only rarely in attempts to subdue prey. Males, who threw more often than females in both combat and hunting, would have been under stronger selection than females to become proficient at the ability to throw, intercept, and dodge projectiles as throwing skills became critical to success in combat and hunting. Therefore, we predict that males, more than females, should display innate anatomical and behavioral traits associated with throwing. We use data from a variety of disciplines to discuss: the sex differences in throwing speed, distance, and accuracy; sex differences in the development of the throwing motion; inability of training or cultural influences to erase the sex differences in throwing; sex differences in the use of throwing in sports, combat, and hunting; and sex differences in anatomical traits associated with throwing that are partly responsible for male throwing superiority. These data contradict the view held by many commentators that socialization rather than innate sex differences in ability are primarily responsible for male throwing superiority. We suggest that throwing is a male adaptation.

Risk Taking Runners Slow More in the Marathon

Frontiers in Psychology, 2019

Gender equality predicts leisure-time physical activity: Benefits for both sexes across 34 countries

Cogent Psychology, 2016

Although countries' gender equality is associated with important health outcomes, especially for ... more Although countries' gender equality is associated with important health outcomes, especially for females, it remains unclear whether gender equality is associated with leisure-time physical activity (LTPA). Data from 34 countries was acquired from the International Social Survey Program, the Pew Research Forum, the United Nations, and the World Bank. Separate analyses were conducted for 21,502 males and 26,652 females. Hierarchal nonlinear Bernoulli modeling was used to examine the association between gender equality and participation in LTPA. Both males and females residing in countries' with higher gender equality were more likely (twice and three times more likely, respectively) to report weekly LTPA than those residing in countries characterized by low gender equality. These effects persisted even when controlling for individual (i.e. age, education) and country-level (i.e. population, gross domestic product) covariates. However, significant variation in LTPA persisted at the country level, suggesting the need for further research. These findings provide novel evidence that both males and females benefit from gender equality. To explain these findings, we hypothesize that increased gender equality decreases the average number of offspring and, in turn, allows mothers more time for leisure, and to invest more resources in both male and female offspring, which may increase LTPA.

Further questions about dehumanization

Journal of Social, Evolutionary, and Cultural Psychology, 2012

It was still late August when one day the door to the Spanish House was flung open, and the two s... more It was still late August when one day the door to the Spanish House was flung open, and the two spinsters were forced to kneel in front of it. Dragged from her wheelchair, the old mother was forced to join them, but she was so feeble that she collapsed into a heap on the terrace. The mob yelled and screamed, banging their fists on every available surface. The old women were called “bloodsucking leeches,”“maggots,” and “intestinal parasites.”

Misrepresentations of Evolutionary Psychology in Sex and Gender Textbooks

Evolutionary Psychology, 2014

Evolutionary psychology has provoked controversy, especially when applied to human sex difference... more Evolutionary psychology has provoked controversy, especially when applied to human sex differences. We hypothesize that this is partly due to misunderstandings of evolutionary psychology that are perpetuated by undergraduate sex and gender textbooks. As an initial test of this hypothesis, we develop a catalog of eight types of errors and document their occurrence in 15 widely used sex and gender textbooks. Consistent with our hypothesis, of the 12 textbooks that discussed evolutionary psychology, all contained at least one error, and the median number of errors was five. The most common types of errors were “Straw Man,” “Biological Determinism,” and “Species Selection.” We conclude by suggesting improvements to undergraduate sex and gender textbooks.

Distance Running as an Ideal Domain for Demonstrating a Sex Difference in Enduring Competitiveness

SSRN Electronic Journal, 2011

Abstract: Men's dominance of cultural displays has been hypothesized to reflect an evolved m... more Abstract: Men's dominance of cultural displays has been hypothesized to reflect an evolved male predisposition for enduring competitiveness. Evidence for this hypothesis is equivocal, however, because there are viable alternative explanations for men's dominance in most display domains. Here I argue that distance running is an ideal domain for addressing this issue. Distance running is ideal because it indicates enduring competitiveness, allows objective comparisons, and is accessible, acceptable, and popular for both men and ...

Book Review: A Big Batch of Mismatch

Evolutionary Psychology, 2014

Most readers of this journal believe that many aspects of our psychology and biology are mismatch... more Most readers of this journal believe that many aspects of our psychology and biology are mismatched to the modern environments we currently inhabit. The standard example is that we have persistent cravings for sugar, salt, fat, and starch because they served us well when we were hunter-gatherers, but these cravings often lead to grave health problems in post-industrial societies. The mismatch perspective is pervasive, even central, to the fields of evolutionary psychology and evolutionary medicine. In fact, every year brings several new books on the topic. Thus, when we learn that a leading evolutionary anatomist, Daniel Lieberman, has written another mismatch book, The Story of the Human Body, two questions arise: First, does his perspective agree with ours, i.e., that mismatches are vitally important? Second, will his background allow him to teach us something new? The answers are emphatically "Yes" and "Yes." Perhaps the book's greatest contribution is its detailed treatment of various health-related mismatches and explanations of how the cultural solutions often produce unintended effects that exacerbate the underlying problems, a process Lieberman calls "dysevolution." Lieberman's book has three parts. Part I, "Apes and Humans," sets the stage, covering everything from our last common ancestor with chimpanzees and gorillas, roughly 8 million years ago, until the end of the paleolithic about 10,000 years ago. It's the story of human evolution in 150 pages, explicating and unifying topics as diverse as recent fossil discoveries (e.g., "Hobbit of Flores"), Lieberman's own groundbreaking work on adaptations for bipedal walking and running, and the evidence bearing on hominid foraging, life history, activity patterns, energetics, and culture. If you never took a topquality human evolution class, Part I will do the job. If you have taken such a course, then this section will get you up to speed on the latest discoveries.

U.S. Masters Track Participation Reveals a Stable Sex Difference in Competitiveness

Evolutionary Psychology, 2014

It is well established that men are more likely than women to engage in direct competition, but i... more It is well established that men are more likely than women to engage in direct competition, but it is unclear if this reflects social structural conditions or evolved predispositions. These hypotheses can be addressed by quantifying competitiveness in sports and testing if the sex difference is decreasing over time in the U.S., a society where social roles have converged. Study 1 assessed participation and the occurrence of relatively fast performances by masters runners (40–74 years old) at recent road races and track meets. Fast performances occurred over 20 times more often at track meets than at road races. Women comprised 55% of finishers at roads races but only 15–28% of finishers at track meets. Thus, the sex difference in masters track participation can serve as a measure of the sex difference in competitiveness. Study 2 used data from national championship meets and yearly rankings lists to test whether the sex difference in masters track participation decreased from 1988–2...

A big batch of mismatch: A review of Daniel E. Lieberman, The Story of the Human Body: Evolution, Health, and Disease

Does the sex difference in competitiveness decrease in selective sub-populations? A test with intercollegiate distance runners

PeerJ, 2015

You can't teach speed: sprinters falsify the deliberate practice model of expertise

PeerJ, 2014

Many scientists agree that expertise requires both innate talent and proper training. Nevertheles... more Many scientists agree that expertise requires both innate talent and proper training. Nevertheless, the highly influential deliberate practice model (DPM) of expertise holds that talent does not exist or makes a negligible contribution to performance. It predicts that initial performance will be unrelated to achieving expertise and that 10 years of deliberate practice is necessary. We tested these predictions in the domain of sprinting. In Studies 1 and 2 we reviewed biographies of 15 Olympic champions and the 20 fastest American men in U.S. history. In all documented cases, sprinters were exceptional prior to initiating training, and most reached world class status rapidly (Study 1 median = 3 years; Study 2 = 7.5). In Study 3 we surveyed U.S. national collegiate championships qualifiers in sprinters (n = 20) and throwers (n = 44). Sprinters recalled being faster as youths than did throwers, whereas throwers recalled greater strength and throwing ability. Sprinters' best perform...

Throwing out the mismatch baby with the paleo-bathwater: A review of Marlene Zuk, Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live

Born at the Wrong Time: Selection Bias in the NHL Draft

Relative age effects (RAEs) occur when those who are relatively older for their age group are mor... more Relative age effects (RAEs) occur when those who are relatively older for their age group are more likely to succeed. RAEs occur reliably in some educational and athletic contexts, yet the causal mechanisms remain unclear. Here we provide the first direct test of one mechanism, selection bias, which can be defined as evaluators granting fewer opportunities to relatively younger individuals than is warranted by their latent ability. Because RAEs are well-established in hockey, we analyzed National Hockey League (NHL) drafts from 1980 to 2006. Compared to those born in the first quarter (i.e., January-March), those born in the third and fourth quarters were drafted more than 40 slots later than their productivity warranted, and they were roughly twice as likely to reach career benchmarks, such as 400 games played or 200 points scored. This selection bias in drafting did not decrease over time, apparently continues to occur, and reduces the playing opportunities of relatively younger players. This bias is remarkable because it is exhibited by professional decision makers evaluating adults in a context where RAEs have been widely publicized. Thus, selection bias based on relative age may be pervasive.

Men are More Likely than Women to Slow in the Marathon

Medicine and science in sports and exercise, Jan 9, 2014

Studies of non-elite distance runners suggest that men are more likely than women to slow their p... more Studies of non-elite distance runners suggest that men are more likely than women to slow their pace in the marathon. This study determined the reliability of the sex difference in pacing across many marathons, and after adjusting women's performances by 12% to address men's greater maximal oxygen uptake and also incorporating information on racing experience. Data was acquired from 14 U.S. marathons in 2011, and encompassed 91,929 performances. For 2,929 runners, we obtained experience data from a race-aggregating website. We operationalized pace maintenance as percentage change in pace observed in the second half of the marathon relative to the first half. Pace maintenance was analyzed as a continuous variable and as two categorical variables: "maintain the pace," defined as slowing < 10%; and "marked slowing," defined as slowing ≥30%. The mean change in pace was 15.6% and 11.7% for men and women, respectively (P<0.0001). This sex difference was s...