Viaggio nel cervello delle donne

Perché i bambini hanno più stereotipi di genere rispetto ai loro genitori?

Le differenze che riscontriamo tra uomini e donne nella vita di tutti i giorni sono quasi sempre un’espansione di quelle già riscontrate nel periodo infantile.

In SEX DIFFERENCES IN INFANCY AND AT PLAY, David Geary ci fa da provvidenziale guida.

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L’età dello sviluppo è fondamentale nell’uomo, lo sappiamo bene. Le durate, nella nostra specie, sono dilatate proprio perché la “macchina” da mettere a punto è particolarmente sofisticata…

… The 15- to 20-year period between weaning and reproduction…

Negli scimpanzé non si va oltre i 5-7 anni.

Si tratta di un periodo molto costoso in termini di dispendio fisico e di vulnerabilità…

… the development of secondary sexual characteristics can be costly… The costs include potential suppression of immune functions, increased risk of predation (e.g., for brightly colored males), and increased aggression from conspecifics, among others….

La maturazione maschile è ritardata anche perché deve essere più “prepotente”…

… delayed maturation allows males to grow larger and gain the social and behavioral competencies needed to compete for and attract mates…

Le bambine maturano prima

girls grow up faster than boys: that is, they reach 50% of their adult height at an earlier age …, enter puberty earlier and cease earlier to grow …. At birth the difference corresponds to 4 to 6 weeks of maturation and at the beginning of puberty to 2 years. (Tanner, 1990, p. 56)…

La probabile logica sottostante: l’età dello sviluppo è costosa, visto che rende i soggetti più vulnerabili. Poiché le bambine sono la risorsa riproduttiva più preziosa della specie, va messa al sicuro quanto prima. Con i bambini invece è razionale rischiare di più: 1) non sono una risorsa così preziosa (basterebbe un uomo per inseminare tutte le donne) 2) ritardare lo sviluppo seleziona i migliori e potenzia lo sviluppo stesso.

Commento: non è solo la società umana che tende a sacrificare l’uomo, è la natura stessa a farlo.

Benefici dello sviluppo ritardato…

… The slower maturation of boys (see Garai & Scheinfeld, 1968; Hutt, 1972) appears to heighten their risk of early mortality but contributes to their adult height; later puberty results in longer legs in men than in women, relative to overall height…

Lo sviluppo maschile è particolarmente laborioso e costoso in termini energetici…

… Boys also develop larger hearts as well as larger skeletal muscles, larger lungs, higher systolic blood pressure, lower resting heart-rate, a greater capacity for carrying oxygen in the blood, and a greater power of neutralizing the chemical products of muscular exercise …. In short, the male becomes more adapted at puberty for the tasks of hunting, fighting and manipulating all sorts of heavy objects. (Tanner, 1990, p. 74)…

I cambiamenti fisici sono dovuti essenzialmente esplosioni ormonali, ma non solo quelli fisici…

… hormonal increase… also influence the expression of a wide range of social, behavioral, and sexual differences (Hayward, 2003). As examples, the hormonal changes influence the emergence of sexual fantasy… For boys, there is a marked increase in sexual behavior, especially masturbation…

Nel corso dell’infanzia le differenze fisiche e comportamentali tra bambini e bambine sono ridotte ma già presenti. La fase successiva è sostanzialmente un’amplificazione di queste differenze…

… During childhood there are small to moderate differences favoring boys in tasks such as grip strength, jumping distance, and running speeds, with large differences emerging during adolescence (Thomas & French, 1985); by 17 years of age, more than 9 out of 10 boys outperform the average girl in these areas…

Le differenze fisiche si traducono poi in una maggior forza e in dimensioni più estese nel maschio…

… As a result of the sex difference in leg length, muscle mass, and cardiovascular capacity, men can run faster, on average, than women (Deaner, 2006). By far, the largest differences in physical competencies are for throwing distance and throwing velocity (Thomas & French, 1985)…

Lo scheletro maschile diventa più adatto al lancio di oggetti…

… The sex differences in throwing skills are related to differences in the structure of the supporting skeletal system. Relative to overall body height, boys have a longer ulna and radius (i.e., forearm), on average, than do girls (Gindhart, 1973)….

Ci sono almeno due ipotesi in campo per giustificare una simile differenziazione: 1) competizione sessuale (i maschi competono tra loro in modo più feroce e necessitano di un fisico diverso) e 2) specializzazione nei compiti (l’uomo caccia, la donna cura i bimbi e raccoglie)…

… some theorists have argued that the physical differences evolved from the division of labor, including men’s hunting, rather than male–male competition (e.g., Kolakowski & Malina, 1974)…

Alcuni indizi privilegiano la prima ipotesi

… Across polygynous primates with intense male–male competition, there is a characteristic pattern of female and male growth…

Alcuni tratti femminili – per esempio le dimensioni ampie della regione pelvica – ci ricordano che la selezione sessuale  è all’opera…

… Of course, some physical sex differences, such as the wider pelvic region in women, have evolved through natural rather than sexual selection. Once the large pelvis evolved, the waist-to-hip ratio that men find attractive emerged and began to be shaped by male choice…

Lo scheletro femminile è più flessibile (si muove meglio in spazi ridotti) e il colpo d’occhio ravvicinato più reattivo…

… Girls are also more physically flexible than boys and have an advantage in fine eye–motor coordination…

La manipolazione “sottile” sembra migliore nelle donne…

… Kimura (1987) argued that the advantage of girls and women might be related to manipulating objects “within personal space, or within arm’s reach, such as food and clothing preparation and child care” (p. 145)…

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Nella fase infantile i bambini sono più vulnerabili delle bambine, il loro metabolismo è più dispendioso e in caso di scarsità di risorse soffrono di più…

… Related to the need to grow larger and stronger than girls is slower growth, beginning prenatally: Boys are born “premature” relative to girls. They have higher activity levels and higher basal metabolic rates than girls, resulting in higher caloric requirements for normal development…

Inoltre, nei giochi, prendono più rischi e si feriscono più di frequente

… Among other social and behavioral sex differences is higher risk taking and accidental injury in boys…

La loro salute è più esposta e risentono di più in caso di malnutrizione

… boys will be more sensitive—suffer more physical, social, and cognitive deficits—than girls when growing up in poor conditions, including poor nutrition, inadequate health care, or poor social stimulation…

Quando le condizioni ambientali non sono ottime sono i maschietti a risentirne: la loro mortalità è più accentuata…

… An analysis of 16,000 infant deaths in the United States between 1983 and 1987, inclusive, revealed that boys had a 38% higher mortality rate due largely to infectious disease during the 1st year of life (J. S. Read, Troendle, & Klebanoff, 1997)…

Le diseguaglianze sociali incidono di più sul benessere dei maschietti…

… Poor early physical development, exposure to parasites, frequent illness, poor nutrition, and inadequate social and cognitive stimulation have been shown to be related to poor long-term cognitive, academic, and social outcomes, even after controlling for SES and other confounds (S. P. Walker, Chang, Powell, & Grantham-McGregor, 2005). Sex differences are not typically reported in these studies, but boys’ risk of poor early growth and development is likely to result in an overrepresentation of boys and men with poor long-term outcomes…

La qualità dell’allattamento e la disponibilità di “giunte” è importante per tutti, ma lo è di più per i bambini che per le bambine…

… Breast-fed infants of both sexes had normal IQ scores at age 8 years… For the two groups that were not breast fed, the risk of cerebral palsy or other significant cognitive impairments was 5 to 6 times higher for boys who received standard formula compared with boys who received the supplement. The risk was not elevated for girls. In fact, the mean IQ of girls was in the average range and did not vary across conditions…

Un ambiente arricchito e una società prospera è quindi un vantaggio soprattutto per i maschietti. Sono loro i maggiori beneficiari di una condizione infantile oggi molto migliore…

… The flip side of boys’ greater vulnerability may be an enhanced potential to benefit more than girls from an enriched environment. This hypothesis has not been tested, although there were hints of such an effect in the Lucas et al. (1998) study…

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I maschietti sono più attratti dalle cose, le femminucce dalle persone. La diversa preferenza sembrerebbe dipendere dagli ormoni…

… M. Alexander (2003) hypothesized that some of the early sex differences in orientation toward people (more in girls) or things (more in boys) reflect the evolved skeletal structure of the visual system, specifically, biases in the what and where visual pathways. Prenatal and early postnatal exposure to androgens may enhance development of the latter and result in attentional and perceptual biases for processing spatial location and object motion…

Le ragazze si concentrano sulle persone, il loro contatto visivo è più frequente e prolungato…

… Orientation toward other people is measured in terms of the duration of eye contact, empathy for others’ distress, and time spent looking at faces, among other behaviors…

La cosa è già riscontrata nel primo giorno di vita

… “there is no doubt that girls and women establish and maintain eye contact more than boys and men. The earliest age for which this is reported is one day”… The sex difference in time spent looking at the face was small but consistent with studies of older infants (McClure, 2000)…

Le ragazzine hanno più memoria per i volti

… By this age, girls might also have a better memory for faces and might be more skilled in discriminating two similar faces (e.g., J. F. Fagan, 1972)…

I maschi si curano più del gruppo, le femmine della relazione binaria

… sex difference in social organization will manifest in the attentional interests of boy (i.e., a focus on groups) and girl (i.e., a focus on individuals) infants…

Le differenze nell’empatia sviluppata dai due sessi sono già evidenti nella prima infanzia…

… Infant girls may react with greater empathy than infant boys to the distress of other people (M. L. Hoffman, 1977). Simner (1971) found that infant girls cried longer than infant boys when exposed to the cry of another infant, but there was no sex difference in reflexive crying when the infants were exposed to artificial noise of the same intensity…

Nel rapporto con i genitori le bambine hanno una marcia in più…

… Studies of the quality of social interactions between parents and infants also reveal that girls are more responsive, and perhaps more sensitive, to social cues than boys (Freedman, 1974; Gunnar & Donahue, 1980; W. D. Rosen, Adamson, & Bakeman, 1992)… In a related study with 6- to 12-month-olds, Gunnar and Donahue (1980) found that mothers were just as likely to attempt to initiate social interactions with their sons as with their daughters, but daughters were much more responsive; Whiting and Edwards (1988) reported the same pattern with older children across cultures…

Il contatto visivo madre-figlia non ha paragoni…

… K. A. Buss, Brooker, and Leuty (2008) found that 2-year-old girls sought contact with and stayed closer to their mother than did boys in a fear-eliciting situation… In an intensive naturalistic study of mother–infant interactions from birth to 3 months, Lavelli and Fogel (2002) found that girls spent more time in face-to-face communication with their mothers than did boys….

I maschietti sono attratti dalla forma, dal colore e dal movimento meccanico degli oggetti. La differenza è ancora maggiore rispetto a quella riscontrata nella sensibilità ai volti…

… In an intensive naturalistic study of mother–infant interactions from birth to 3 months, Lavelli and Fogel (2002) found that girls spent more time in face-to-face communication with their mothers than did boys….

Riassumendo…

… Males appear to be more likely to store information about the various components of a repeatedly presented stimulus, for example, its form and color …. [while] females, unlike males, are more likely to store information about the consequences of orienting. (p. 382)…

Queste differenze sono correlate con l’esposizione prenatale al testosterone

… Baron-Cohen and his colleagues have been studying how prenatal exposure to testosterone influences sex differences in infancy and in older children (Baron-Cohen, Lutchmaya, & Knickmeyer, 2004; Lutchmaya, Baron-Cohen, & Raggatt, 2002a, 2002b)… Testosterone gets into the amniotic fluid by diffusion through the fetus’s skin and through urination…

Testosterone e contatto visivo

… Lutchmaya et al. (2002a) examined the relation between prenatal testosterone levels and the frequency with which 12-month-olds made eye contact with their mother… Prenatal testosterone levels were, however, related to how often the boys made eye contact but not in a straightforward way…

Testosterone e linguaggio

… Lutchmaya et al. (2002b) assessed the vocabulary of boys and girls at 18 and 24 months. At 18 months, the vocabulary of girls was more than double that of boys. At 24 months, the typical girl knew 40% more words than did the typical boy. At this age, higher prenatal testosterone levels were associated with lower vocabulary scores…

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Bambini e bambine giocano diversamente, è un dato universale…

… sex differences in play activities are a universal aspect of children’s behavior…

A sei mesi il sessismo dei bambini è già notevole…

… Infants begin to make sex-based discriminations (e.g., between male and female voices) as early as 6 months of age (C. L. Martin, Ruble, & Szkrybalo, 2002). By 18 months, they are beginning to categorize some activities as male typical and others as female typical (Eichstedt, Serbin, Poulin-DuBois, & Sen, 2002), and they talk about these as 2-year-olds (S. A. Gelman, Taylor, & Nguyen, 2004)…

I bambini piccoli hanno molti più stereotipi di genere dei loro genitori…

… children are often more stereotyped than their parents and other adults (e.g., S. A. Gelman et al., 2004)…

Un genitore puo’ togliere alcuni stereotipi alla prole ma difficilmente cambia i loro comportamenti effettivi

… Girls and boys segregate into same-sex groups whether or not they are engaging in sex-typed activities (Maccoby, 1988), and children raised by egalitarian parents—those who actively discourage sex typing—have less stereotyped beliefs about sex differences than do children raised in other types of families, but their toy and play preferences are the same as these other children (Weisner & Wilson-Mitchell, 1990)…

I bambini giocano alla lotta, le bambine alla mamma. Il dato è universale…

… Rough-and-tumble play is more common among boys and play parenting is more common among girls… The sex difference in rough-and-tumble play emerges by age 3 years… This sex difference is found in all modern societies…

Quanto più i bambini vengono lasciati liberi (assenza di un adulto supervisore), tanto più hanno comportamenti e preferenze stereotipate…

… The sex difference is most evident with groups of three or more children and in the absence of adult supervision…

I ragazzini nutrono un maggior interesse per il gruppo

… The sex difference in infants’ interest in groups (Benenson et al., 2004) continues into childhood and beyond. These studies confirm that boys organize themselves into much larger social groups than do girls, engage in intergroup competition once such groups are formed, form within-group dominance hierarchies, and show within-group role differentiation and specialization when engaged in group-level competition (Eder & Hallinan, 1978; Lever, 1978)… More often, boys compete as members of teams and must simultaneously coordinate their actions with those of their teammates while taking into account the action and strategies of their opponents…

Tra giochi, ormoni e stereotipi esiste una forte correlazione…

… Collaer and Hines (1995) concluded that the “clearest evidence for hormonal influences on human behavioral development comes from studies of childhood play. Elevated androgen in genetic females …is associated with masculinized and defeminized play” (p. 92)…

Qui i soggetti sperimentali più preziosi sono quelle bambine esposte a livelli ormonali vicini a quelli maschili…

… excess levels of androgens (i.e., affected by congenital adrenal hyperplasia [CAH])…

In effetti, i comportamenti di queste bambine si avvicinano a quelli maschili…

… In an observational study, Hines and Kaufman (1994) found that girls affected by CAH engaged in more playful physical assaults, physical assaults on objects, wrestling, and rough-and-tumble play in general than did unaffected girls, but none of these differences were statistically significant…

Le bambine amano giocare alla mamma. Il dato è uniforme in tutte le culture…

… Throughout the world, girls are assigned child-care roles, especially for infants, more frequently than are boys (Whiting & Edwards, 1988). Girls also seek out and engage in child care, play parenting, and other domestic activities (e.g., playing house) with younger children or child substitutes such as dolls more frequently than do same-age boys (Pitcher & Schultz, 1983)…

E’ comune anche alle culture antiche e agli altri primati

… In sum, a sex difference in play parenting favoring girls is found in both modern and traditional societies and in fact most other species of primate (Eibl-Eibesfeldt, 1989; Nicolson, 1987)…

E per quanto riguarda i giochi esplorativi e itineranti?

In quasi tutte le società l’uomo si muove e viaggia di più

… Across traditional societies, men travel farther from the home village than do women for many reasons, including finding mates, developing alliances with the men of neighboring villages, hunting, and intergroup warfare (Chagnon, 1997; K. Hill & Hurtado, 1996; K. Hill & Kaplan, 1988)… Women’s foraging, in contrast, typically occurs within the group’s territory… Unlike women’s foraging for fruit or tubers, hunting requires an ability to track and predict the movements of evasive prey, human and nonhuman…

In genere nei giochi maschili si occupa più spazio, si compete e si corre di più…

… The sex difference is related in part to the sex difference in group-level competitive play and to a greater engagement of boys than girls in solitary running (Eaton & Enns, 1986; Lever, 1978)… During juvenility and beyond, boys have a larger play range than girls…

Nei giochi maschili si esplora e si manipola la natura con maggior frequenza…

… Whenever it emerges, boys not only engage in more locomotor activities over a larger range than girls but also explore and manipulate (e.g., build things, such as forts) the ecology much more frequently (Matthews, 1992)…

I maschi hanno maggior facilità nel farsi delle mappe mentali del territorio…

… ecological exploration is correlated with the ability to generate mental maps of the physical layout of the ecology but is not consistently related to other forms of spatial cognition, such as the ability to copy geometric figures (R. H. Munroe et al., 1985)…

E anche nel risolvere problemi che coinvolgono la dimensione spaziale

… Scientists do know that 4-year-old boys, and perhaps even infant boys (D. S. Moore & Johnson, 2008; Quinn & Liben, 2008), have an advantage over same-age girls on some spatial tasks (Levine, Huttenlocher, Tayler, & Langrock, 1999) and that this advantage grows during juvenility, puberty, and adolescence (Matthews, 1992; D. Voyer, Voyer, & Bryden, 1995)…

Questa differenza nelle abilità scompare tra i bambini delle famiglie disagiate

… Levine et al. assessed 547 children from high-, middle-, and low-income backgrounds across second and third grades on two spatial tasks—map reading and two-dimensional mental rotation—and a syntax comprehension test. No sex differences were found on the syntax test, but boys from high- and middle-income families had an advantage on both spatial tasks. There was no sex difference on either spatial task for children from low-income families. In other words, low family income was associated with lower scores for both boys and girls on all three tests…

I maschietti amano giocare con gli oggetti

… Boys engage in much more object-oriented play than do girls (Eibl-Eibesfeldt, 1989; Freedman, 1974; Sandberg & Meyer-Bahlburg, 1994; Sutton-Smith et al., 1963)…

Talune differenziali nelle abilità derivano direttamente da questa attitudine…

… An analysis of the relation between the focus of play activities and the pattern of cognitive abilities indicated that children whose play was object oriented “performed better on tests of ability to organize and classify physical materials” (Jennings, 1975, p. 515), as assessed by tests of spatial cognition (e.g., the ability to mentally represent and manipulate geometric designs) and the ability to sort objects on the basis of, for example, color and shape…

Anche le differenze vocazionali sono interessate…

… As I review elsewhere (Geary, 1998b), there are sex differences in interest in and pursuit of careers that involve designing and working with mechanical objects, as in engineering and computer technology…

Altre evidenze del discrimine…

… Chen and Siegler (2000) found that as early as 18 months of age, boys have small to moderate advantages over girls in several aspects of early tool use, as in using a hooked stick to retrieve a desired toy. Boys were better at applying tool-related knowledge learned in one setting to another setting, were more consistent in the use of tools across settings, and were more successful in the use of tools in problem solving. Without any hints from an adult, 79% of the boys and 31% of the girls were able to use such tools to retrieve the toy…

Ci sono poi i giochi di ruolo. I ruoli preferiti da maschi e femmine sono molto diversi…

… Both boys and girls regularly engage in sociodramatic play but differ in the associated themes and the roles they tend to adopt, as noted by Pitcher and Schultz (1983): Boys play more varied and global roles that are more characterized by fantasy and power. Boys’ sex roles tend to be functional, defined by action plans. Characters are usually stereotyped and flat with habitual attitudes and personality features (cowboy, foreman, Batman, Superman). Girls prefer family roles, especially the more traditional roles of daughter and mother. Even at the youngest age, girls are quite knowledgeable about the details and subtleties in these roles …. From a very early age girls conceive of the family as a system of relationships and a complex of reciprocal actions and attitudes. (p. 79)…

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Il modello maschile e quello femminile emergono già nell’infanzia. Un resoconto delle differenze è messo a disposizione da David Geary in “SEX DIFFERENCES IN SOCIAL DEVELOPMENT”.

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Ai bambini piace giocare con compagni appartenenti al proprio sesso

… The formation of same-sex play and social groups is one of the most consistently found features of children’s behavior (Maccoby, 1988, 1998; Strayer & Santos, 1996; Whiting & Edwards, 1988)…

Questa preferenza si esprime anche prima dei 3 anni. Prima ancora che il bambino conosca la differenza tra maschi e femmine.

Il tempo speso con i propri simili è molto superiore…

… In a longitudinal study of children in the United States, Maccoby and Jacklin (1987) found that 4- to 5-year-olds spent 3 hours playing with same-sex peers for every single hour they spent playing in mixed-sex groups. By the time these children were 6 to 7 years old, the ratio of time spent in same-sex versus mixed-sex groups was 11:1…

La tendenza è comune a molti paesi, è credibile ritenere che sia universale

… The same pattern has been documented in Canada, England, Hungry, Kenya, Mexico, the Philippines, Japan, and India (Strayer & Santos, 1996; P. J. Turner & Gervai, 1995; Whiting & Edwards, 1988), although the degree of segregation varies across these societies…

Più libertà, più segregazione tra i sessi…

… The social segregation is most common in situations that are not monitored by adults, that is, when children are free to form their own groups (Maccoby, 1988; Strayer & Santos, 1996)…

Nei gruppi segregati per sesso gli stili adottati per avere accesso ad una risorsa scarsa (per esempio il dolce o il programma TV preferito) varia di parecchio…

… In situations in which access to a desired object, such as a movie viewer that can be watched by only one child at a time, is limited, boys and girls use different strategies, on average, for gaining access to this object (Charlesworth & Dzur, 1987). More often than not, boys gain access by playfully shoving and pushing other boys out of the way, whereas girls gain access by means of verbal persuasion (e.g., polite suggestions to share) and sometimes verbal commands (e.g., “It’s my turn now!”)…

Un maschietto è sordo allo stile femminile.

Gli ormoni sono correlati allo stile dei giochi…

… The sex difference in play interests is related to prenatal exposure to male hormones… social correlates of amniotic testosterone levels…

La segregazione spontanea rafforza le differenze

… The net result of sex segregation is that boys and girls spend much of their childhood in distinct peer cultures (J. R. Harris, 1995; Maccoby, 1988). It is in the context of these cultures that differences in the social styles and preferences of girls and boys become larger and congeal (C. L. Martin & Fabes, 2001)…

Il gruppo maschile e quello femminile socializzano in modo molto diverso e le differenze sono ben spiegate dal modello evoluzionista

… children’s attentional, behavioral, and social systems are inherently biased such that they will recreate the forms of relationship (e.g., as in mother–infant attachment) and experience that help them navigate the developmental process and that prepare them for the survival and reproductive demands of our adult ancestors (Caporael, 1997)…

A contare è la forza della coalizione che si crea ma anche la propria posizione all’interno della coalizione…

… The coalitions are of course fluid because the gains of victory are distributed—often unequally according to dominance rank—among coalition members. The result is a balance between the benefits of having a large enough ingroup coalition to be competitive against the costs of having to share gains with ingroup members…

I ragazzini, per esempio, creano legami tra pari meno intensi (più formali) ma anche più estesi…

… In comparison with girls and women, boys and men are predicted to have a lower threshold for forming cooperative same-sex social relationships; their relationships are predicted to be more easily maintained (e.g., with less time-intensive disclosure) and evince a greater tolerance for interpersonal conflict. The results from studies of peer relationships support all of these predicted sex differences (Benenson & Christakos, 2003; Benenson et al., 2009; Eder & Hallinan, 1978; Rose & Rudolph, 2006; Whitesell & Harter, 1996). Tolerance for conflict is necessary to maintain the coalition and at the same time compete for within-coalition status. Dominance striving must, at the same time, be balanced against the cost of potentially losing the coalitional support of other boys and men…

La scarsa intimità delle amicizie e la maggiore tolleranza al conflitto consente di realizzare coalizioni più estese e quindi più idonee ad affrontare un nemico esterno. L’estensione dell’alleanza era sinonimo di forza, almeno un tempo.

Le ragazzine creano tra loro relazioni più intime e altruistiche…

… women’s relationships are more heavily dependent on reciprocal altruism than those of boys…

Se l’amicizia maschile è sostanzialmente un alleanza (basta la formalità), quella femminile è un sostegno emotivo (è necessaria l’intimità)…

… The principle benefit for girls and women is a core set of relationships that provide social, emotional, and interpersonal stability, particularly support during times of interpersonal conflict with other individuals, such as a spouse…

Funzioni diverse generano caratteristiche diverse.

Savin e Williams nel 1987 osservarono per 5 settimane le dinamiche sociali in un campo estivo per ragazzi (dai 12 ai 16 anni).

La segregazione spontanea tra i sessi era la regola.

Mezzi per stabilire le gerarchie all’interno di ciascun gruppo: i ragazzi insultano le ragazze spettegolano

… Within these same-sex groups, both boys and girls formed dominance hierarchies and frequently used ridicule to establish social dominance, such as name calling (“homo,” “perverted groin”) or gossiping; social…

Tempi diversi: i ragazzi competono subito, le ragazze si studiano di più…

… In some groups, boys began their bid for dominance within hours of arriving in the cabin, whereas most of the girls were superficially polite for the first week and then began to exhibit dominance-related behaviors…

Vediamo più da vicino i metodi maschili

… Boys’ dominance-related behaviors included ridicule, as noted previously, as well as directives (“Get my dessert for me.”), counterdominance statements (“Eat me.”), and physical assertion (e.g., play wrestling, pillow fights, sometimes actual physical fights). More than 90% of the time these behaviors were visible to all group members, were clearly directed at one other boy, and were attempts to establish dominance over this individual…

E quelli femminili

… Girls used ridicule, recognition, and verbal directives to establish social dominance but used physical assertion only one third as frequently as did boys. In contrast to boys’ blatant behaviors, more than one half of the girls’ dominance behaviors were indirect

Dopo un certo periodo – Isola dei Famosi docet – il gruppo degli uomini risulta più stabile, quello femminile più disgregato, probabilmente la cosa dipende dagli standard più elevati delle donne…

… As documented in other studies (J. G. Parker & Seal, 1996), Savin-Williams (1987) found that by the end of summer camp boys’ groups showed greater stability and cohesiveness relative to the 1st week of camp. Most of the girls’ groups, in contrast, were on the verge of splintering or had already split into “status cliques based on popularity, beauty, athletics, and sociability” (Savin-Williams, 1987, p. 124)…

Andy, il maschio dominante nel campeggio…

… Andy [the alpha male] immediately grabbed the flag cloth and penciled a design; he turned to Gar for advice, but none was given. Otto [low ranking] shouted several moments later, “I didn’t say you could do it!” Ignoring this interference, Andy wrote the tribal name at the top of the flag. Meanwhile, Delvin and Otto were throwing sticks at each other with Gar watching and giggling. SW [the counselor] suggested that all should participate by drawing a design proposal on paper and the winning one, as determined by group vote, would be drawn on the flag…. Andy, who had not participated in the “contest,” now drew a bicentennial sunset; it was readily accepted by the others. Without consultation, Andy drew his design as Gar and Delvin watched. Gar suggested an alteration but Andy told him “Stupid idea,” and continued drawing. Otto, who had been playing in the fireplace, came over and screamed, “I didn’t tell ya to draw that you Bastard Andy!” Andy’s reply was almost predictable, “Tough shit, boy!” (Savin-Williams, 1987, p. 79)…

Ann, la femmina dominante del campeggio…

… [Her] style of authority [was] subtle and manipulative, she became the cabin’s “mother.” She instructed the others on cleanup jobs, corrected Opal’s table manners (“Dottie, pass Opal a napkin so she can wipe the jelly off her face.”), and woke up the group in the morning …. Ann became powerful in the cabin by first blocking Becky’s [the beta female] dominance initiations through refusing and shunning and then through ignoring her during the next three weeks. By the fifth week of camp Ann effectively controlled Becky by physical assertion, ridicule, and directive behaviors. (Savin-Williams, 1987, p. 92)…

Tratti in comune…

… For both boys and girls, the achievement of social dominance was related to athletic ability, physical maturity, and leadership…

In generale le relazioni tra ragazze si addolciscono nel tempo

… Ahlgren and Johnson found that at about the time of puberty, girls’ social motives become more cooperative and less competitive than those of their younger peers…

Ma anche quelle tra ragazzi, man mano che ci si inoltra nell’adolescenza…

… Boys’ relationships changed as well. By late adolescence, boys’ group-level games were characterized by greater focus and organization, with fewer negative criticisms and more encouragement directed toward ingroup peers than was found with younger boys (Savin-Williams, 1987)…

Diciamo che si impara ad evitare le guerre inutili. oppure a condurle sottotraccia in modo da non compromettere del tutto l’amicizia.

I ragazzi prediligono il gruppo, le ragazze l’amicizia di coppia

… Whereas the typical boy is engaged in some form of activity that involves groups of his friends, the typical girl is talking with one of her friends…

L’amicizia femminile è più esclusiva. Lo richiede la funzione del supporto emotivo…

… In comparison with boys’ friendships, girls’ friendships are characterized by higher levels of emotional support and more frequent intimate exchanges (e.g., talking about their problems) and are a more central source of help and guidance in solving social and other problems (Maccoby, 1990; J…

Le ragazze sono meno brusche e più disposte al compromesso

… Conflicts of interest are common among friends of both sexes, but girls invest more in resolving these conflicts and attempt to do so through accommodation, compromise…

Ma sono anche più sensibili, quindi i danni intra-gruppo in termini di aggressività indiretta possono essere anche più devastanti…

… girls are more sensitive to personal slights on the part of their best friend and respond with more initial and lingering negative affect (e.g., sadness, anger) than do boys (Whitesell & Harter, 1996)…

Nella socializzazione i ragazzi si concentrano sulla dominanza, le ragazze sull’empatia

… boys’ and men’s concerns about social dominance and their relative hierarchical position and girls’ and women’s social agreeableness and tendency to nurture is found across modern and traditional societies (e.g., Del Giudice, 2009a; Feingold, 1994; Whiting & Edwards, 1988)…

Anche quando la dominanza è un obbiettivo femminile, assume una forma meno egoistica.

Nel linguaggio le ragazze sono meno aspre dei ragazzi…

… “tender-mindedness” (i.e., nurturance and empathy), favoring women, and assertiveness (e.g., dominance-related activities), favoring men…

Le ragazze cooperano, i ragazzi competono

… At all grade levels, girls endorsed cooperative social behaviors more frequently did than boys, whereas boys endorsed competitive social behaviors more frequently than did girls…

Nei giudizi morali le ragazze sono più sensibili all’eguaglianza e alla non-violenza…

… girls and women consistently endorse a moral ethos that espouses equality in social relationships and an avoidance of the harm of others…

***

Il cervello degli uomini è diverso da quello delle donne. La cosa è vera sia in senso letterale che in senso metaforico.

Approfondiamo la delicata questione accompagnati dal massimo esperto in materio: David Geary. Il suo saggio si intitola “Sex Differences In Folk Psychology”.

***

La storia dell’umanità ha registrato una convergenza nelle caratteristiche fisiche del cervello di uomo e donna…

… The reduction in the sex difference in physical size since the australopithecines and the corresponding reduction in the variability across hominid brain volumes make it very likely that the average brain size of our male and female ancestors has converged since the emergence of Homo…

Tuttavia, molte differenze esistono ancora.

Il cervello dell’uomo è più grande e pesante rispetto a quello della donna…

… Pakkenberg and Gundersen (1997) found that in comparison with women’s brains, men’s brains, on average, are 13% heavier, occupy 15% more volume, and contain 16% more neurons, among other differences… M. Leonard et al. (2008) found that the overall brain size of more than 9 out of 10 men was larger than that of the average woman… The 10% male advantage in brain size is found in newborns and continues into childhood, juvenility, and adolescence…

Il cervello maschile ha più materia grigia e bianca (ma solo in senso assoluto)…

… Overall, men have more gray matter (neuronal cell bodies and dendrites that collect information from other cells) and white matter (neuronal axons that transmit information to other cells) than women…

L’area più sviluppata del cervello femminile è quella relativa alle competenze linguistiche…

… The areas of enhanced thickness in women are associated with language skills…

Sulla coesione dei due emisferi la storia è controversa ma sembra che nelle donne sia più presente: l’uomo è più specializzato, la donna più integrata

… One of the more controversial findings concerns the corpus callosum, the bundle of axons that allows communication across the left and right hemispheres. De Lacoste-Utamsing and Holloway (1982) reported that the back portion of the callosum was shaped differently in men and women and that relative to overall brain weight was larger in women. They speculated “that the female brain is less well lateralized—that is, manifests less hemispheric specialization…

***

Le relazioni tra ormoni e cervello sono molte e rilevanti. Tra gli ormoni il testosterone spicca per importanza…

… These studies have focused on whether prenatal exposure to testosterone or estrogens (which can be converted to testosterone) results in male-typical patterns of brain organization or functioning…

Come dicevamo prima, il cervello maschile sembra più “specializzato”. Ebbene, le donne mancine e affette da CAH (una patologia contratta per sovraesposizione ormonale) registrano una tipologia vicina a quella maschile…

… More men than women are left-handed, and language and spatial functions tend to be more strongly localized in the left and right hemispheres, respectively, in men and distributed across both hemispheres in women (McGlone, 1980; Witelson, 1976, 1991). Kelso, Nicholls, Warne, and Zacharin (2000) found more left-handers and better nonverbal than verbal abilities for girls and women with CAH…

Le recenti scannerizzazioni FMRI confermano il ruolo parallelo dell’amigdala nei maschi e nelle femmine CAH…

… An intriguing example is provided by a brain imaging study of amygdala activation, which is involved in the processing of emotionally and sexually laden information, when individuals with CAH viewed facial expressions that conveyed neutral and negative affect (i.e., fear or anger; Ernst et al., 2007);…

***

Quando una donna pensa a sé pensa al suo ruolo in famiglia…

… When reflecting on or describing themselves (e.g., completing “I am …”), women are more likely than men to view themselves in terms of close relationships with family members or friends, whereas men are more likely to view themselves as members of groups or teams (Gabriel & Gardner, 1999)…

Le donne sono più sensibili ai giudizi sfumati, allusivi, ambigui… e anche più abili nell’usarli…

… girls and women appear to be more aware of nuances in their feelings and emotions than boys and men and have better memories for the details of emotionally charged personal experiences (Barrett, Lane, Sechrest, & Schwartz, 2000)… My interpretation is that girls and women are better able to use awareness of their feelings as a social barometer…

Le donne appaiono più ossessionate dal loro corpo

… In general, girls and women tend to reflect on their behavior and traits more frequently than do boys and men across many domains (Fejfar & Hoyle, 2000), and their bodies are a common area of reflection…

La cosa si giustifica poiché la bellezza è l’elemento chiave nella competizione sessuale tra donne.

***

Il linguaggio non verbale (per esempio la lettura dei volti) è una specialità femminile…

… Girls and women are better than boys and men at interpreting and sending nonverbal social messages, including skill at reading emotional states conveyed in facial expressions, gesture, and body language and in generating nuance in the social use of these forms of communication (Buck, Savin, Miller, & Caul,1972; J. A. Hall, 1978, 1984; J. A. Hall & Matsumoto, 2004; McClure, 2000; Rosenthal, Hall, DiMatteo, Rogers, & Archer, 1979; van Beek & Dubas, 2008; Wagner, Buck, & Winterbotham, 1993)…

Non sorprende che l’amigdala (una componente fisica del cervello pesantemente coinvolta in queste funzioni) si presenti differenziata nella donna rispetto all’uomo…

… amygdala is among the core brain systems involved in the processing of emotion-laden information and is structurally and functionally different in women and men (e.g., Goldstein et al., 2001; Kilpatrick et al., 2006)…

Lo stesso dicasi per la corteccia pre-frontale

… After correcting for the sex difference in brain size and size of the frontal cortex, the social–emotional processing areas of the prefrontal cortex are larger in women than in men…

Lo stesso dicasi per i due emisferi cerebrali (più connessioni in quello sinistro per le donne e in quello destro per gli uomini)…

… In addition to the sex differences in proportional size of the amygdala (larger in men) and ventromedial prefrontal cortex (larger in women), these regions are interconnected differently in women and men (Kirkpatrick et al., 2006; Tranel, Damasio, Denburg, & Bechara, 2005). There appears to be greater functional connectivity between these regions in the right hemisphere for men and the left hemisphere for women…

Lo sviluppo dell’amigdala sembra particolarmente sensibile al testosterone, presente in quantità diverse nei corpi di uomini e donne…

… prenatal exposure to male testosterone may bias the later functioning of the amygdala (Ernst et al., 2007), and men’s larger amygdala may be due to the pubertal increase in testosterone (Neufang et al., 2009)…

Sul linguaggio, la differenza non riguarda tanto la loquacità…

… Girls talk more than boys during the first 2 years of life and during the juvenile period (about 10–13 years), but boys may talk more during adolescence (Leaper & Smith, 2004). At…

… quanto la pragmatica: gli uomini sono più assertivi, le donne più sfumate e “relazionali”…

… Pragmatics refers to the use of language in social contexts. Boys and men tend to use language to attempt to assert their social dominance…

I vantaggi linguistici della donna sono comunque innumerevoli…

… Relative to boys and men, girls and women have advantages for many basic language-related skills, including the length and quality of utterances (e.g., in their utterances women show standard grammatical structure and a correct pronunciation of language sounds more frequently than do men), the ease and speed of articulating complex words, the ability to generate strings of words, the speed of retrieving individual words from long-term memory, and skill at discriminating basic language sounds from one another (R. A. Block, Arnott, Quigley, & Lynch, 1989; D. F. Halpern, 2000; Hampson, 1990a; Hyde & Linn, 1988; Majeres, 2007)…

***

Le donne sembrano più concentrate dell’uomo sui figli, sulla famiglia e sui parenti. La parentela è centrale nelle preoccupazioni femminili.  Lo sguardo maschile è più ad ampio raggio

… women are predicted to invest more in their children than are men, as is the case for mammals in general (Clutton-Brock, 1991). Ample support for this prediction was provided in chapter 6 of this volume…

I maschi però restano curiosamente interessati ai parenti maschi

… A less obvious prediction is that men will show a bias for male kin, especially when their group is engaged in frequent intergroup conflict…

Parlando di socializzazione abbiamo già visto come i gruppi maschili funzionino meglio, mentre quelli femminili tendono a disgregarsi: le femmine si appassionano di più al rapporto due a due.

Tuttavia, gli uomini registrano una maggiore intolleranza per gli omosessuali maschili…

… I assume gay men are discriminated against by other men because of an implicit assumption that gay men’s contributions to male–male coalitional competition will be limited; whether this is the case remains to be determined…

Forse perché si tratta di soggetti poco interessati all’alleanza guerresca.

***

E le relazioni con lo straniero? E nel tessere alleanze con i gruppi avversari, cosa differenzia uomo e donna? 

Le donne sembrano più abili quando i gruppi sono di pari forza, gli uomini a trattare una pace cooperante in caso di guerra asimmetrica…

… intergroup cooperation was lower for men but not for women when the ingroup and the outgroup were equally matched (L. E. Davis et al., 1996)…

Congettura: la donna è fondamentalmente disinteressata allo straniero anonimo, nel senso anche che lo combatte con più riluttanza se non minaccia la sua famiglia (è difficile che una donna si presti, per esempio, ad uccidere uno sconosciuto premendo un bottone). ma il suo fondamentale disinteresse puo’ essere prezioso quando l’uomo va in crisi perché coinvolto in una situazione di stallo (parità di forze).

E per quanto riguarda l’identificazione sociale (esempio, patriottismo)? Gli uomini sembrerebbero più sensibili anche se le donne, almeno se toccate dal conflitto, partecipano poi con grande spirito…

social identification enables the formation of larger and therefore more competitive social groups, and one of the core selection pressures for the establishment and maintenance of large competitive groups is coalitional male–male competition… If this hypothesis is correct, then social identification with competitive groups (e.g., a sports team, a nationality) should be more easily instantiated in men than in women…

Ad ogni modo, almeno nel caso del patriottismo, le similitudini sono più numerose che le differenze.

***

Le donne sembrano più attratte dalla flora di un ambiente. Berlin, Boster, e O’Neill hanno studiato gli Aguaruna, una popolazione che vive nel nord del Perù…

… women showed more agreement among themselves about the classification of these species, showed greater complexity in their overall classification system, and had more nuanced knowledge about individual species…

Altro caso che conferma la maggior competenza femminile in fatto di fiori e frutti…

… In a study of the Paniya and Kuruma tribes in India, Cruz García (2006) found that mothers were more knowledgeable of local plants than fathers and passed this folk biological knowledge to their children; children also learn from other adults and from peers (Setalaphruk & Price, 2007)…

In Brasile, idem…

… Bay region of Brazil, women showed greater knowledge of medicinal plants than did men…

Sulla fauna le competenze si invertono…

… Given men’s greater participation in hunting in traditional societies, it is not surprising that they have more complex knowledge of local fauna than do women…

Se si racconta di animali pericolosi i ragazzini si eccitano molto più delle ragazzine…

… In support of the predicted developmental sex difference, there is some indication that boys attend to potentially dangerous and wild animals more often than do girls and know more about these animals (Blurton Jones, Hawkes, & O’Connell, 1997; Eibl-Eibesfeldt, 1989; Setalaphruk & Price, 2007)…

La sperimentazione dà non poche conferme di queste inclinazioni  anche per le società moderne (dove ragazze e ragazzi vivono in un ambiente urbano impoverito di flora e fauna)…

… For normal adults, McKenna and Parry (1994) found that women were better at naming fruits and vegetables and men were better at naming animals, but other studies have not found this sex difference (Barbarotto et al., 2002); men are better at naming tools, however (see the section titled Tool Use later in this chapter)…

La spiegazione evoluzionista è quasi banale: gli uomini cacciano le donne raccolgono.

E in effetti, quando passeggio con le mie bimbe raramente posso tornare a casa senza aver raccolto un mazzolin di fiori. Non penso che con dei maschietti sarebbe la stessa cosa (probabilmente tortureremo ragni e lucertole)…

Detto questo l’origine dei divide, a livello fisiologico, resta abbastanza misterioso…

… At this point, scientists do not know enough to draw firm conclusions about the origin of the sex differences in folk biological competencies…

Si deve ripiegare su un generico “attentional bias” che emerge da una combinazione fisiologica (cervello+ormoni) difficile da ricostruire…

… I suspect the differences arise from the combination of sex differences inherent in attentional and interest biases and corresponding sex differences in engagement with the biological world. The tendency of boys to attend to wild and potentially dangerous animals more frequently than girls might reflect such an attentional bias, and their play hunting, a corresponding activity that would eventually result in a sex difference favoring men, might result in knowledge of local fauna (Blurton Jones et al., 1997; Eibl-Eibesfeldt, 1989)…

***

Nel valutare gli oggetti in movimento i maschi, che, oltre ad essere più sensibili agli oggetti in generale, sono più sensibili al “dove” rispetto al “cosa”, restano avvantaggiati…

… I return to G. M. Alexander’s (2003) hypothesis about the development of the where as contrasted with the what stream of the visual system (see the section titled Infancy, chap. 10, this volume), specifically, that prenatal and early postnatal exposure to testosterone may enhance aspects of the development and functioning of the where system and result in a sex difference favoring boys in interest in object motion…

Anche per questo prevalgono nel rintracciare in laboratorio gli oggetti in movimento improvvisamente occultati…

… sex differences in the detection of objects obscured in a complex visual scene, detecting and tracking the movement of objects in physical space, and skill at behaviorally reacting to these moving objects (Law et al., 1993; Peters, 1997; Schiff & Oldak, 1990)…

Nelle prove su oggetti in movimenti gli uomini hanno vantaggi visuali mentre le donne si affidano ad altri sensi che in loro sono più sviluppati…

… Men show several advantages in the visual system, even though women have more sensitive sensory systems in the areas of touch, smell, taste, and some aspects of hearing…

L’unico parametro visuale in cui la donna a volte prevale è il colore

… About 8% of men have varying degrees of color blindness, that is, they are poor at discriminating colors in the red–green spectrum; about 2% of men cannot discriminate red from green at all (Nathans, Piantanida, Eddy, Shows, & Hogness, 1986). Discrimination of red from green appears to be an evolved feature of the primate visual system that supports the detection of fruit and other colorful foods (Shyue et al., 1995), and thus these men should be at an evolutionary disadvantage…

Gli uomini sono più abili nell’identificare velocità e traiettoria

… Men also show advantages in the ability to judge the velocity and trajectory of a moving object, generate visual images of a moving object, estimate when an object moving directly toward them will hit them, and hit a moving object with a thrown projectile (Pavio & Clark, 1991; Schiff & Oldak, 1990)…

I ragazzi sono più abili nell’intercettare, mirare e colpire bersagli in movimento. nelle “uscite” i portieri donna sono disastrosi…

… As I mentioned in chapter 10 of this volume (in the section titled Physical Competencies), boys and men have a very large advantage over same-age girls and women in throwing distance, velocity, and accuracy (Thomas & French, 1985)…

I ragazzi sono più abili nel dominare la rotazione spaziale, le ragazze identificano meglio gli oggetti in uno spazio specifico…

… Men typically outperform women on tests that involve the representation and mental rotation of images in three-dimensional space (see Figure 13.2), and women outperform men on some memory tasks…

I ragazzi sono più abili nel generare mappe mentali dopo l’esplorazione di un territorio sconosciuto…

… When asked to generate a map after exploring a novel environment, boys’ maps showed more accurate clustering of environmental features and more accurate representations of the geometric relations—cardinal direction (e.g., Building A is northwest of Building B)—among these features (Matthews, 1992)…

In un ambiente nuovo è più facile che le donne prendano a riferimento cippi e costruzioni (immobili) mentre gli uomini strade (direzionate) e punti cardinali (astrazioni)…

… Boys and girls also differed in the extent to which they focused on landmarks (e.g., specific buildings) or routes (e.g., roadways) in their maps. In this study and others, girls have been found to attend more to landmarks and relative direction (Building A is left of Building B) and boys to routes and cardinal direction (see also J. Choi & Silverman, 2003)…

Le ragazze sono più abili nella ricerca di oggetti specifici in un ambiente familiare (tradotto: se non trovi le chiavi dell’auto chiedi alla moglie)…

… Boys’ and men’s advantages in the ability to generate representations of novel environments and to mentally manipulate three-dimensional images stand in sharp contrast to girls’ and women’s advantages in certain forms of visuospatial memory (Eals & Silverman, 1994; T. W. James & Kimura, 1997)…

La costruzione e l’uso di strumenti vede gli uomini partire con molti vantaggi…

… tool construction is much more common among men than women across traditional societies (Daly & Wilson, 1983; Murdock, 1981); boys have a better intuitive sense of how to use objects as tools and learn how to use tools more quickly than do girls (Z. Chen & Siegler, 2000; Gredlein & Bjorklund, 2005)…

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Un pensiero riguardo “Viaggio nel cervello delle donne”

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