We’ve all read some of the discussions about differences in men’s and women’s brains, but the case of throwing overhand offers a cautionary tale about thinking we’ve found something inherent in being male or female. The danger is that we accept too quickly observed differences without digging a bit deeper into their variation and potential causes. In the United States, most of our readers will have run across the idea that women throw like, well, … girls.

Janet Shibley Hyde, one of the leading proponents of the ‘gender similarity hypothesis,’ concedes that there are some marked differences between men and women, singling out throwing ability as the most pronounced among them (2007: 260; see also 2005).

Thomas and French (1985: 266 & 276), in a meta-analysis reviewing all available research on sex differences in throwing, found that the gap stood at 1.5 standard deviations at three years of age, and increased over time, widening to between three and five standard deviations by puberty. By contrast, the much discussed ‘math gap’ between boys and girls, in Hyde’s meta-analysis of 48 studies, was a +0.08 on problem solving and +0.16 on national math tests (Hyde 2005; 2007: 260). In other words, if you’re impressed by the gap in math scores (I’m not), you should be awestruck at the gap in throwing ability.

I just finished writing the draft of a potential book chapter on throwing ability for a volume Prof. Robert Sands is putting together on biocultural approaches to sports. The chapter steps off from my observations that most of my colleagues in Brazil, men included, ‘threw like girls’ even though they were incredibly talented athletes, some of the most astounding capoeira practitioners I have ever seen. The book chapter is linked to some other work I’ve been doing, so I’ve got notes enough for several chapters – I thought I might put some up on Neuroanthropology.net because they were especially related to some of the things we focus on here.

This is probably going to wind up being at least two or three posts, so in this one, I’m only going to discuss the neurological issues surrounding throwing and the likely mechanical or technical issues that make (some) women (and Brazilian men and others) ‘throw like girls.’ At least one more post is going to deal with physiological plasticity beyond the nervous system, such as the way throwing remodels the shoulder, to explore anatomical plasticity more broadly, but you’re going to have to come back later for that one…

Do all women throw like girls?

The book chapter I just submitted explores the ineptness of Brazilian men at throwing in light of the late phenomenologist and philosopher Iris Marion Young’s (1990) remarkable paper on ‘throwing like a girl.’ Young suggests that the inept throwing motion of girls arises from three signature feminine motor traits: self-consciousness, inhibition, and kinetic dis-unity of the body (although she uses more sophisticated terminology to describe each). If you’re interested in Young’s discussion and related pieces, you may want to look at a book review here and her obituary here.

I have a number of issues with Young’s analysis, although I think her work is incredibly important, a landmark piece for anyone interested in phenomenological approaches to motor learning or embodiment. When I teach about phenomenology in anthropology, it’s one of the first pieces I turn to for its clarity and persuasiveness. I may come back to some of my other objections at a later date, but here I want to specifically focus on the neural and technical dimensions of skill acquisition in throwing to offer a more neuroanthropological perspective on ‘throwing like a girl,’ one that doesn’t argue this throwing style arises from existential or essential traits of being feminine.

The reason for this is simple: since the passage of the Patsy T. Mink Equal Opportunity in Education Act (commonly known as ‘Title IX’) – and even before, for that matter – many women have learned how to throw very hard, most without significantly jeopardizing their femininity (that’s sarcastic understatement, in case it doesn’t come through in print). (Young also wrote about Title IX in Young [1998], but she came to different conclusions than I do.)

For example, Olympic softball pitcher Jennie Finch regularly struck out any Major League Baseball batter brave (or fool) enough to take the ‘Jennie Challenge’ on This Week in Baseball (here’s a You Tube video from FSN Sport Science testing whether it’s harder to hit a baseball or a Jennie Finch pitch; Finch broke the force plate with her pitching before she dusted some poor prospect from the Arizona Diamondbacks.). And although they do not reach the highest velocities found in men’s throwing, elite female athletes reach velocities far in excess of average men, especially when we take into account their smaller size, shorter arms, and lighter musculature.

(For more on softball pitching see, Why Is It So Hard to Hit a Softball? Rob Neyer in Slate Magazine.)

An ironic footnote to the question of whether or not women can throw is the case of Virne Beatrice ‘Jackie’ Mitchell Gilbert (see the entry for Ms. Mitchell at the Baseball Hall of Fame) who pitched for the Chattanooga Lookouts Class AA minor league baseball team. In a 1931 exhibition game against the New York Yankees, she struck out Babe Ruth and Lou Gehrig back-to-back (although the Lookouts went on to lose 14-4), only to have the commissioner of baseball nullify her contract the next day because baseball was ‘too strenuous’ for women. Just this past year, a 16-year-old Japanese knuckleballer, Eri Yoshida, was signed by the Kobe 9 Cruise professional team.

If women can acquire the skill to throw overhand (witness Olympic softball fielders), then the question should be, instead of why do girls ‘throw like girls,’ why do some girls throw so poorly if they are capable of throwing well? Most students of the biomechanics of throwing would argue that it’s a technical problem: women don’t throw properly and the technique that they put together is hampered by a number of kinaesthetic problems, some of which obscure avenues of further skill development.

Learning to throw

In a series of research papers, Mary Ann Roberton explored how children learned to throw. Roberton broke with the influential model of developmental stages in learning to throw that had been proposed first by Monica Wild (1938), and later refined by other researchers. These stage models posited the existence of predictable levels of development from one type of technique to the next.

Wild had used photographs to distinguish among four different stages in the unfolding of skilful throwing. The model of stages, like Piaget’s or Freud’s more general models of cognitive and psychological stages of development, helped to illuminate the progressive nature of skill acquisition; in fact, virtually all novice throwers ‘throw like girls,’ but the more skilful ones go on to develop more sophisticated techniques. (When I say ‘virtually all,’ I simply mean that there are other ways to be incompetent; for example, the novice ‘wild pitcher’ may be overly uninhibited, flailing explosively and launching the ball in an almost random direction.)

The downside of a ‘stage’ model like Wild’s, however, is that it tends to artificially homogenize development and, at the same time, suggest that a contingent process was much more orderly than it might actually be (which was an empirical question concealed by theoretical assumption). If a person did not progress beyond a particular stage, they suffered from arrested development (my phrase, in this case)

Developmental systems theorists like Esther Thelen (see Thelen 1995; Thelen and Smith 1996) have pointed out this general problem with staged developmental models, like those proposed by Piaget; in fact, children often take very different developmental trajectories even in the emergence of basic skills like reaching or walking. Children must experiment with their own bodies and develop different facets of a whole body skill.

The fact that we eventually all learn how to walk leads some theorists to assume that the ability to walk, which emerges from almost all children’s motor learning but not in the same way, is instead pre-programmed into the person. Without a more exacting analysis, it simply appeared that women who ‘threw like girls’ had a kind of derailleur of kinaesthetic development that hampered them or that they were simply evidencing an innate feminine style of movement which could develop no further.

Roberton suggested, based on more elaborate analysis of kinematic data, that throwing ability didn’t demonstrate the clear succession of developmental stages, but rather advanced unevenly in different parts of the body (1977, 1978; Roberton and Halverson 1984; Roberton and Konczak 2001). Roberton recognized that a throw was assembled from different kinaesthetic elements, and that one part could grow more sophisticated while another part lagged behind.

For example, a child might improve his or her arm motion without necessarily developing contralateral (opposite foot) stepping. Even though the physical experimentation was likely not fully conscious (although it might be subject to coaching or self examination), children were in fact experimenting at the envelope of their kinaesthetic ability, which often produced unstable techniques, liable to vary without much control.

Roberton’s approach to throwing ability does not contradict Young’s perspective directly, but it does open up a much more subtle way of approaching the nature and origins of ineptness. Specifically, we can ask where in the throwing motion does female inferiority arise: do women actually do the same motion with less force, or do they do a different motion, as the idea ‘throwing like a girl’ suggests? (I’m not going to deal here with the question of accuracy, but will instead focus on force; if you’re interested in the ‘spatial accuracy’ issue, see especially Duffy, Ericsson and Baluch’s [2007] analysis of dart throwing, where biomechanical ability to generate force is less of an issue.)

The brain assembling the motion

Throwing is a physically demanding task, placing enormous strains on the body at elite levels, as I will discuss in a later post, but it is also a neurologically difficult task in several respects. The first, and most basic challenge is simply the complex motor management of all the muscles and joints in the body that contribute to the throw.

An expert throw is a kinaesthetic cascade that begins with a windup in which the body, counter-intuitively, swivels in the opposite direction from the eventual throw, turns the shoulder on the throwing arm back, and lifts the opposite foot to pivot backwards. The throw progresses to a forward step on the contralateral foot while the arm actually cocks in the opposite direction. Finally, during the acceleration phase, the momentum generated successively by the step, rotation of the pelvis, rotation of the torso, twisting of the shoulder, elbow straightening and wrist extending, must be transferred between body parts, stabilized, and then, suddenly, once the ball is released, decelerated and dissipated in the follow-through.

In summary, the brain and nervous system have to orchestrate a complex sequence of movements in a very short period of time; the whole movement is only around 2 seconds in a major league pitcher, and 1.5 seconds of this is the preparation, before the ball is accelerated to release.

Some recent research highlights how other primates also throw food, for example (see Westergaard et al. 2000), but humans significantly out-perform other primates in overhand throwing. There’s lots of nice things to say about chimpanzee brains, but don’t expect a chimp to be bowling yorkers in cricket or pitching knuckle-balls unless they make some remarkable leaps in control of their limbs.

We tend to think of our neurological difference from other primates as being primarily cognitive; we expect to be better than chimps at chess, math problems, and self-analysis. But we also have significant motor differences from our hairy brethren; the fact that we can train up our nervous system, and have the behavioural and social supports to channel our extended neuroplasticity, makes it possible to develop specialized motor abilities that other apes cannot challenge. Only a human has the brain, as well as the society and technology, to devote hours of adolescence to perfecting skateboard tricks that have no bearing on our survival chances.

When a child – boy or girl – first learns to throw, he or she is confronted by this terribly difficult coordination task, one that requires counter-intuitive motions and precise sequencing of high-speed motions fused into an integrated motor synthesis. Expert technique is quite simply impossible for a beginner to accomplish because the novice has to explore the movements, as it were, from the inside, learning about the capacities of the body and the dynamic links one can make between its parts through experience. Although this process is largely non-conscious, it can be affected by conscious processes such as coaching, self-coaching, and conceptually motivated training techniques (see Downey 2008).

Degrees of freedom as a problem

Russian anatomist Nicholai Bernstein (1996) referred to this coordination problem as an overabundance of ‘degrees of freedom.’ The human body has so many joints that it’s difficult to reliably coordinate their movement; not only do they have too much freedom, but we now know that muscle fibres themselves don’t even respond identically each time to a uniform nerve impulse.

Kari M. Newell (1996:413), drawing on Bernstein, argues that all novices contend with the ‘degrees of freedom’ problem by ‘freezing’ most of the body:

Because the basic problem of coordination is the harnessing of the extreme abundance of degrees of freedom of the system, the first stage in learning is characterized by coordination solutions that reduce the number of degrees of freedom at the periphery to a minimum. The freezing strategy effectively reduces the number of biomechanical degrees that need to be coordinated and controlled.

‘Throwing like a girl’ is not so much a defective technique as it is a normal and even effective strategy for dealing with body management when a person is not experienced coordinating certain sorts of complex whole-body movements. Even experts often engage in ‘girl-like’ throwing when asked to throw for accuracy, at short range, in an activity like darts or many classic carnival games. That is, a person’s strategy for throwing can shift depending upon the demands made of the activity.

As Roberton’s work has suggested, novice technique itself can be unstable, coming together in different kinaesthetic configurations depending upon the task environment. In other words, get a Little Leaguer trying to throw quickly in an unfamiliar position, and he (or she) is liable to lose control of parts of the motion or revert to a less sophisticated technique.

While the brain has to learn how to assemble the kinetic chain of expert overhand throwing, the experience of throwing has to reorganize, recruit, and even generate the neural resources it needs for the task. Improvement in the neurological control over muscles, for example, can lead to strength gain, even in the absence of changes in the cross-section of the muscles, as Yue and Cole (1992) showed by having subjects visualize doing hand exercises.

Research on skill acquisition suggests that training, over time, leads to reorganization of the primary motor cortex, changing its functional organization and excitability (see, for example, Adkins et al. 2006; Karni et al. 1996; Kelly and Garavan 2005; Rosenkranz, Kacar, and Rothwell 2007). Klein and colleagues (2004), for example, found in rats that the late stages of skill learning involved motor map reorganization and the generation of new synapses. They conclude that the brain changes involved in skilful action take significant time and repetition to occur.

As they write: “The results demonstrate the temporally dynamic nature of learning-dependent plasticity that occurs within a single brain region during training on a single task and show how different phases of learning may be supported by different forms of plasticity” (ibid.: 632).

Learning to throw overhand remodels neural resources to make certain forms of coordination possible; from this perspective, the ineptness of some women (and men) at throwing overhand needs less study and explanation than the transformation of bodies and brains that leads to elite athletes’ performance. Ineptness is the normal outcome of not allocating neural resources to a task.

So why do they throw differently?

For a more complete discussion of that question, you’re going to have to come back for another post. This is getting a bit long, but I want to wrap this part up. I’ll give you a bit of the punch line right now, but there will be more on this by the end of the week.

In a forthcoming article in Behavioural Brain Research, Shoshi Dorfberger, Esther Adi-Japha, and Avi Karni (forthcoming) suggest one possible answer to the question of why women throw differently: that male-female differences in performance on motor tasks may arise, not from innate ability, but from a more efficient learning process in men after puberty. They found that male subjects, post-adolescence, benefited more from training, especially after having some time to consolidate learning. Their discussion reports:

Taken together, our results therefore suggest that given a similar amount of motor training, males benefited more than females in the performance of the trained movement sequences. This effect was age dependent with the male advantage becoming significant in the post-puberty group, the 17-year-old participants. Moreover, males from all three age-groups were found to evolve significantly larger delayed (consolidation phase/between session) gains, and these were well retained for 6 weeks. Thus, the male advantage was most significant in the post-training motor consolidation and retention phase; the current results suggest therefore that males, especially after adolescence, may have an advantage, over females, in procedural memory consolidation.

There are some caveats to this research, which I’ll discuss in the later postings, but in general, I like their explanatory approach. Rather than just looking at the tail end of what might be a complex causal chain and saying, ‘Girls throw like girls because of girl-ness,’ they try to sort out more specifically what the differences might be.

To me, the failure to demand this specificity of causation is at the heart of essentialist approaches to answering problems, whether they be genetic essentialist or endocrine essentialist or phenomenological essentialist. Take a complex causal change and just ignore it with some simplistic gloss that fits the categories you already believe.

For example, an essentialist perspective might argue that men and women throw definitely because of ‘hormones,’ and then just drop the question, without explaining which endocrine processes affect what part of the throw or how. Before some commenter writes — ‘you believe there’s no difference between men and women!’ (I don’t) — I’m not against acknowledging differences between men and women; in fact, I think we should be exploring them more carefully. But the resulting story is likely to be a bit more intricate than an essentialist explanations that ‘boyness’ or ‘girlness’ causes something.

To me ‘masculinity’ and ‘femininity’ are squishy, culturally-specific gender descriptors applied indiscriminately to biological, ideological, behavioural, cultural, and other traits. To treat either descriptor of a pattern as the cause of that pattern begs all the crucial questions.

For example, in the case of throwing, we know that some of the gap between men’ and women’s average throwing velocity likely arises from limb length and muscle mass. Jennie Finch has a leverage advantage because she’s around six feet tall, and you will often find that baseball pitchers are taller than average. The averages of size and limb length clearly differ between men and women, although there’s a fair bit of overlap, and we have a pretty good understanding of some of the endocrine causes of these overall size differences between the sexes. If you control for size and muscle mass, according to researchers like van den Tillaar and Ettema (2004), you have no residual effect of a person’s sex on throwing velocity. That’s intriguing, but we still have this yawning gap in technique, not just velocity, to study and explain.

If the difference in motor learning described by Dorfberger, Adi-Japha, and Karni were the only significant cause of male-female differences in throwing, we would also expect to see it across all skilled motor activity, not just throwing. As a sometime dance instructor, I can definitively say that men do not always have an obvious advantage over women when it comes to learning motor techniques, even whole-body motor techniques.

Clearly, men and women are different, but how they are distinct, and the developmental processes that actually lead to the manifest divergences, are what I find more interesting. The error of essentialism is not saying that there are differences between men and women, but in being content with flimsy non-explanations, offering stereotypes rather than compelling accounts of the origins of patterns.

Don’t worry, this is just the intro. I want to get into the details more, including research on throwing techniques in other cultures and some of the evolutionary arguments. More soon, and I’ll post links to the successive chapters here in updates as I go…

References cited:

Adkins, DeAnna L., Jeffery Boychuk, Michael S. Remple, and Jeffrey A. Kleim. 2006. “Motor training induces experience-specific patterns of plasticity across motor cortex and spinal cord.” Journal of Applied Physiology 101(6): 1776-1782. doi:10.1152/japplphysiol.00515.2006. (pdf available here)

Bernstein, Nicholai A. 1996. “On Dexterity and Development.” Translated by Mark L. Latash. In Dexterity and Its Development. Edited by Mark L. Latash and Michael T. Turvey. Pp. 1-244. Mahwah, New Jersey: Lawrence Erlbaum Associates.

Calvin, William H. 1983. “A stone’s throw and its launch window: timing and precision and its implications for language and hominid brains.” Journal of Theoretical Biology 104:121-135. (online version at Calvin’s homepage)
_____. 1991. “Did Throwing Stones Lead to Bigger Brains?” In The Throwing Madonna: Essays on the Brain. Bantam. (Chapter online here)

Dorfberger, Shoshi, Esther Adi-Japha, and Avi Karni. Forthcoming. “Sex differences in motor performance and motor learning in children and adolescents: An increasing male advantage in motor learning and consolidation phase gains.” Behavioural Brain Research. doi:10.1016/j.bbr.2008.10.033. (abstract)

Downey, Greg. 2008. “Scaffolding Imitation in Capoeira: Physical Education and Enculturation in an Afro-Brazilian Art.” American Anthropologist 110(2): 204-213. doi:10.1111/j.1548-1433.2008.00026.x (abstract)

Duffy, Linda J., K. Anders Ericsson, and Bahman Baluch. 2007. “In Search of the Loci for Sex Differences in Throwing: The Effects of Physical Size and Differential Recruitment Rates on High Level Dart Performance.” Research Quarterly for Exercise and Sport 78(1): 71-78. (abstract)

Hyde, Janet Shibley. 2005. “The Gender Similarity Hypothesis.” American Psychologist 60(6): 581-592. doi:10.1037/0003-066X.60.6.581 (pdf of article)
_____. 2007. “New Directions in the Study of Gender Similarities and Differences.” Current Directions in Psychological Science 16(5): 259-263. doi:10.1111/j.1467-8721.2007.00516.x (abstract)

Karni, Avi, Gundela Meyer, Christine Rey-Hipolito, Peter Jezzard, Michelle M. Adams, Robert Turner, and Leslie G. Ungerleider. 1998. “The acquisition of skilled motor performance: fast and slow experience-driven changes in primary motor cortex.” Proceedings of the National Academy of Science USA 95(3): 861–868, 1998. (abstract with link to pdf)

Kelly, A. M. Clare, and Hugh Garavan. 2005. “Human Functional Neuroimaging of Brain Changes Associated with Practice.” Cerebral Cortex 15(8): 1089-1102. doi:10.1093/cercor/bhi005. (abstract, pdf of article)

Kleim, Jeffrey A., Theresa M. Hogg, Penny M. VandenBerg, Natalie R. Cooper, Rochelle Bruneau, and Michael Remple. 2004. “Cortical synaptogenesis and motor map reorganization occur during late, but not early, phase of motor skill learning.” Journal of Neuroscience 24(3): 628–633. doi:10.1523/JNEUROSCI.3440-03.2004 (abstract, pdf of article)

Newell, Kari M. 1996. “Change in Movement and Skill: Learning, Retention and Transfer.” In Dexterity and Its Development. Edited by Mark L. Latash and Michael T. Turvey. Pp. 393-430. Mahwah, New Jersey: Lawrence Erlbaum Associates.

Roberton, Mary Ann. 1977. “Stability of stage categorizations across trials: Implications for the ‘stage theory’ of overarm throw development.” Journal of Human Movement Studies 3: 49-59.
_____. 1978. “Longitudinal evidence for developmental stages in the forceful overarm throw.” Journal of Human Movement Studies 4: 167-175.

Roberton, Mary Ann, and Lolas E. Halverson. 1984. Developing Children: Their Changing Movement. Philadelphia: Lea & Febiger.

Roberton, Mary Ann, and Jürgen Konczak. 2001. “Predicting Children’s Overarm Throw Ball Velocities from Their Developmental Levels in Throwing.” Research Quarterly for Exercise and Sport 72(2): 91-103.

Rosenkranz, Karin, Aleksandra Kacar, and John C. Rothwell. 2007. “Differential Modulation of Motor Cortical Plasticity and Excitability in Early and Late Phases of Human Motor Learning.” Journal of Neuroscience 27(44): 12058 –12066. doi:10.1523/JNEUROSCI.2663-07.2007 (abstract, pdf of article)

Thelen, Esther. 1995. “Motor Development: A New Synthesis.” American Psychologist 50 (2): 79-95. (abstract)

Thelen, Esther, and Linda B. Smith. 1996. A Dynamic Systems Approach to the Development of Cognition and Action. Cambridge, MA: MIT Press/Bradford Books.

Thomas, Jerry R., and Karen E. French. 1985. “Gender differences across age in motor performance: A meta-analysis.” Psychological Bulletin 98: 260-282.

van den Tillaar, Roland, and Gertjan Ettema. 2004. “Effect of body size and gender in overarm throwing performance.” European Journal of Applied Physiology 91(4): 413-418. doi:10.1007/s00421-003-1019-8 (abstract)

Westergaard, G. C., C. Liv, M. K. Haynie and S. J. Suomi. 2000. “A comparative study of aimed throwing by monkeys and humans.” Neuropsychologia 38: 1511–1517. (available here as pdf download)

Wild, Monica. 1938. “The behavior pattern of throwing and some observations concerning its course of development in children.” Research Quarterly 9: 20-24.

Young, Iris Marion. 1990. Throwing Like a Girl and Other Essays in Feminist Philosophy and Social Theory. Bloomington and Indianapolis: Indiana University Press. (Google book link)
_____. 1998. “‘Throwing Like a Girl’: Twenty Years Later.” In Body and Flesh: A Philosophical Reader. Donn Welton, ed. Pp. 286-290. Oxford: Blackwell Publishers.

Yue, Guang, and Kelly J. Cole. 1992. “Strength Increases from the Motor Program: Comparison of Training with Maximal Voluntary and Imagined Muscle Contractions.” Journal of Neuropsychology 67(5): 1114-1123. (abstract, pdf behind subscription wall — sad, it’s a great piece.)