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✒ Grupo: Bogdan; Sumaya; Filipe; Leonardo; Henrique

◦DIVERSIDADE◦

A diversidade humana remete para as diferenças entre as várias comunidades existentes no mundo, podendo ser considerada diversidade biológica, social, funcional e cultural.​

➺Diversidade biológica- Somos todos seres iguais mas biologicamente distintos. Isto porque, todos nós partilhamos uma constituição genética muito semelhante (99,9%), porém os 0,1% restantes são responsáveis pelas nossas diferenças pessoais.

➺Diversidade funcional- Todos nós temos cérebros que são iguais (anatomicamente) e que funcionam de modo semelhante. A diferença encontra-se a nível das redes neuronais, isto graças á plasticidade cerebral, que permite um desenvolvimento cerebral totalmente relacionado e dependente de aprendizagens e experiências adquiridas no meio em que cada um se encontra.

➺Diversidade cultural- Existem inúmeras culturas, pelo que não é possível definir padrões culturais comuns a todas elas.
Um indivíduo não é capaz de se desenvolver sem cultura, ou seja, sem aprender as regras básicas, atitudes e valores  do grupo social em que se encontra inserido.

➺Diversidade social- A diversidade social consiste no encontro de pessoas de diferentes lugares e com experiências de vida variadas. Em cada contexto que um indivíduo possa experienciar vão haver situações que poderão ser significativas e que serão cruciais na formação da sua própria identidade pessoal. Engloba inúmeras etnias, culturas,religiões, linguagem, classes sociais,etc...

Com este trabalho, começa-se por definir cada tipo de diversidade, porém, dá-se uma ênfase maior sobre as diverisdades biológica e cultural na medida em que apresentamos aspetos contrastantes/ antagónicos entre etnias, culturas distintas de modo a que sejam perceptíveis as diferenças que nos tornam seres tão únicos.

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Colin Kaepernick é ativista de direitos civis e jogador de futebol americano que jogava na posição de quarterback na National Football League. Nesta série, ele relembra as suas experiências como um adolescente negro que teve que lidar com questões de raça, classe, cultura.

✒ Grupo: Bogdan; Sumaya; Felipe; Leonardo; Henrique

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Watch Colin in Black & White | Netflix Official Site

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Colin Kaepernick narrates this drama series recounting his formative years navigating race, class and culture while aspiring for greatness. Watch trailers & learn more.

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Experiência social que “divide” as pessoas em função de certas características/ comportamentos. Mas no fundo, apesar de todas as diferenças, somos todos iguais.

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✒ Grupo: Bogdan; Sumaya; Filipe; Leonardo; Henrique

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Aculturação - exemplos de como a sociedade portuguesa foi incorporando elementos de outras culturas (hábitos, ideias,  valores, etc.)
Grupo: Gustavo Silva, Diana Santos, Tatiana, Larissa, Guilherme Coelho

Padrões de Cultura são um conjunto de comportamentos padronizados de acordo com as tradições, costumes, hábitos, crenças , localização geográfica e experiências do grupo para estabelecer padrões de comportamento. O Padrão de cultura mostra-nos como nos devemos comportar de modo a promover um sentimento de normalidade. Eles promovem a integridade e adaptação social dos indivíduos, criam uma identidade social e permitem a manutenção da identidade de um grupo. Apesar de estáveis eles podem sofrer alterações por virtude de:
-Autocrítica;
-Alterações econômicas, políticas ou naturais;
-Aculturação.

Aculturação é um processo dinâmico no qual ocorre a interação direta de mais de uma cultura, que irá originar a criação e adoção de conjuntos de elementos culturais e ainda novos padrões de cultura. Gerando o aparecimento de novas criações culturais, ou seja formas renovadas de viver e compreender o mundo, o que não deixa de fora o desaparecimento de vários elementos culturais. Existem ainda vários tipos de aculturação como por exemplo:
Aculturação direta- Baseia-se na imigração, colonização, e guerras;
Aculturação indireta- Influência dos meios de comunicação atuais, como redes sociais, jornais, e televisão.
Aculturação material- Que é a escolha de marcas e modelos de uma cultura dominante por determinadas populações.
Aculturação formal- Ocorre quando uma população que vive numa determinada cultura altera a sua forma de pensar, isto é, tenta enquadrar-se também na cultura do país onde se encontra.

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Ted Talk que nos fala mais sobre a diversidade biológica e como diferentes grupos de indivíduos se adaptam e moldam a língua.

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✒ Grupo: Bogdan; Sumaya; Filipe; Leonardo; Henrique

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Biological diversity and the origin of language | Wassima Fahsi | TEDxTUBerlin

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Elementos culturais que constituem o padrão de cultura portuguesa 

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Elementos culturais que constituem o padrão de cultura portuguesa 

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Elementos culturais que constituem o padrão de cultura portuguesa
Grupo: Diana Sousa, Margarida, Rita, Rafael M. e Tomás

A cultura consiste nas produções humanas que visam a adaptação ao meio, designa tudo aquilo que é adquirido através da aprendizagem e da nossa relação com os outros. Os elementos instrumentais são de natureza material e têm como função garantir a satisfação das necessidades básicas (objetos naturais, tecnológicos e bens imóveis). Os elementos ideológicos são de natureza imaterial e visam dar coerência e organizar os comportamentos e a vida em sociedade (normas, valores, hábitos,...).
Padrão de cultura é um conjunto de comportamentos coletivamente estabelecidos, que nos permitem identificar um indivíduo como membro de uma sociedade.

O nosso tema são os elementos culturais que constituem o padrão de cultura portuguesa.  Os nossos conhecimentos atuais não nos permitem desenvolver satisfatoriamente este tema. Pois, é como se estivéssemos a falar de uma coisa que ainda não terminou, a cultura está sempre a mudar. A herança cultural de um povo é extremamente afetada por influências do exterior, isto são, aculturações e por transformações de estrutura determinadas pela sua própria evolução. Além disso, as várias regiões da nação portuguesa apresentam, dentro das mesmas, uma determinada diversidade cultural, agravada ainda pelas diferenças culturais próprias dos estatutos sociais que a formam.

Para desenvolver este tema, começamos por falar sobre como são os portugueses, principalmente em termos de atitudes e de personalidade, em seguida, falamos sobre algumas partes da nossa cultura (hábitos, festividades, artes, instituições e valores) e por fim achamos por bem falar sobre os elementos principais que caracterizam o nosso país, mesmo alguns já tendo sido referidos anteriormente.

NOTA: O power point que está anexado a esta publicação está em pdf, porque, em power point, o ficheiro é muito grande, e o padlet não permite publicar documentos maiores que 30 Mb.

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A diversidade humana: diversidade biológica, funcional, cultural e social. Exemplos e sua apreciação. Podem referir-se, se assim o desejarem à diversidade humana numa sociedade. Podem referir-se a diferenças culturais e sociais relativamente a aspetos específicos. Fotos, vídeos, documentários.

Grupo: Gustavo Dias, Gonçalo, Mário; Alexandre, Bemfeita

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Estudo feito em cegos que desenvolveram novas conexões neuronais após terem aprendido a ler Braille.

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✒ Grupo: Bogdan; Sumaya; Filipe; Leonardo; Henrique

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SUMMARY

This article brings review of the studies and their findings about neuroplasticity of the brain and Braille reading, as well as some connections between the two. The goal of the article is to combine knowledge from different disciplines, thus enabling development of new efficient programs in rehabilitation. A lot of research has shown the possibility of brain reorganization (plasticity), indicating the creation of new neuron connections in people with vision loss which relate to Braille reading, especially in late-onset vision loss.

Key words: Neural plasticity, Brain, Visual cortex, Vision disorders, Blindness - rehabilitation

Introduction

When looking at the history of research about Braille reading, most researchers focused on reading achievement, reading rate, hand movement and dominance, learning media, reading process and assessment, tactile perception and contracted Braille versus uncontracted Braille reading. Development of neuroscience and medical technologies has resulted in new research findings becoming ever more important for workers in the educational field (1). Multidisciplinary approach brings new and better rehabilitation programs as they offer better understanding of brain processes after vision loss and reveal a range of potential recovery and/or development in individuals taking into account congenital, early- or late-onset vision loss. Scientists are lifting boundaries in beliefs about brain development by constantly searching and learning new findings (2).

This article will describe the research in brain plasticity and its importance for visually impaired people. A description of processes in a Braille reader's brain and the way blind people 'see' will be presented, as well as some new findings from neuroscience and their application.

Anatomy behind the Process of Reading (Print and Braille)

The brain is divided into four main lobes. Each lobe (frontal, parietal, occipital and temporal) has been associated with different functions and purposes imperative to human living. Researchers examine neuron activity in visual and parietal lobes because of their importance in Braille reading (1, 3). In order to understand the research of the brain plasticity and tactile reading, it is important to understand the anatomy and neurology of visual and somatosensory pathways.

Visual pathway starts with the eye and transformation of light signals from the environment into neuron impulses in the retina. This visual information travels through the optic nerve, optic chiasm and optic tract to the thalamus, more specifically to two lateral geniculate nuclei (LGN), one in each hemisphere of the brain. LGN are the information processing control centers where visual information is sorted into three brain areas: primary visual cortex (information about form, color, shape, dimension, orientation), superior colliculi (motion information) and pretectal area (photoreceptor information that helps regulate the circadian clock) (1).

Is visual cortex active in people without visual stimulation? Researchers have provided evidence regarding brain possibility to reorganize itself in the absence of visual stimuli or during new skill development (e.g., tactile reading).

According to Sadato, visual cortex of the blind during Braille reading has a role in tactile processing. It gives meaningful lexical and semantic properties to simple tactile information. Sighted people recognize and process letters by their visual characteristics in the visual cortex, whereas in Braille reading, the somatosensory system is responsible for letter perception. This ability of the primary visual cortex to additionally process tactile information provides evidence for the outstanding brain plasticity of early-onset blind subjects and therefore is functionally relevant to Braille reading ability (4).

The somatosensory path starts with sensory receptor cells (thermoreceptors, photoreceptors, mechanoreceptors and chemoreceptors). Neuron impulses travel in sensory nerves through the spinal cord to the thalamus and terminate in the ventrolateral posterior nucleus (VPL) or intralaminar nuclei. VPL is the control center for somatic sensory information processing (touch, temperature, pain, vibration and pressure). The VPL sends signals to the primary somatosensory area in the parietal lobe of the cerebral cortex, where tactile processing mainly occurs. After being sorted, information goes to the secondary somatosensory cortex or to other areas of the brain. Hannan describes moving fingertips over the tactile stimulus of raised dots as part of Braille reading. He states that isolating specific areas used for tactile perception during Braille reading movement is very difficult. The problem lays in brain scanning techniques that measure overall cortical activity and factors like number of fingers used, left or right hand use, and reading movement techniques (1).

Somatosensory path receives information from the skin, which is the largest organ of the human body. Mechanical stimulation of the skin will cause different conscious sensations. Four main types of mechanoreceptors, which differ in their ability to signal the speed and intensity of the stimulus, are located in the skin of palms and fingers. Fingertips and palms do not have identical mechanoreceptors. Fingertip skin is most sensitive to mechanical stimuli. It has 4 main types of mechanoreceptors, one type of rapidly adapting (RA) receptor and slowly adapting (SA) receptor in the skin and one type of RA and SA receptors in the subcutaneous tissue. Skin RA receptors are Meissner corpuscles (most numerous in fingertips), and skin SA receptors are Merkel tiles. Subcutaneous RA receptors are pacinian corpuscles, and SA receptors are Ruffini's corpuscles. RA receptors have great importance in Braille reading because they provide essential information about mechanical stimuli time line (sequence), which is important for the analysis of information during an active touch (palpation or finger swiping on a surface to determine if it is rough, smooth, etc.). If Braille readers are not allowed to move their index fingers from side to side between the letters, but only apply light vertical pressure, they are not able to read (5).

Neuroplasticity

Neuroplasticity is the ability of the neurons to create new connections and paths with new roles in the cortex. Neuroplasticity means reorganization of the brain. It is the ability of the brain to change its molecular, micro-architectural and functional organization or reorganize itself as a response to normal development/maturation of the body, experience, acquisition of new skills, sensory stimulation, deprivation and injury (6).

Several studies have provided evidence for neuroplastic changes in healthy human brains as a result of learning (7, 8). Damage to the brain breaks the original neuron network, which then strives to regenerate, i.e. reorganize (9).

Diamond and Hopson describe a research by neurologist Huttenlocher. He observed the visual cortex and discovered an increase in synaptic connections from the seventh month of pregnancy to birth and two months after birth. An expansion by tenth happened during second and fourth month, which the author connected to the improvement in child's vision in that age and the ability to create three-dimensional images. The number of synapses reaches its maximum around eight months. It persisted until the age of four years, after which a gradual decrease occurred, the density of synapses evened out and remained the same to maturity. This decrease in the number of synapses forms the visual cortex. The dendritic branches of the remaining synapses in the visual cortex keep extending and sprouting, therefore creating new synapses. They also describe another research of visual cortex development in kittens by Hubel and Wiesel, performed in 1978. By patching one of the kittens' eyes right after birth, for three months, they discovered the kittens were blind although the visual apparatus of the patched eye was not damaged. Visual deficiency in the beginning of life changed the cortex to receive visual impulses only from the unpatched eye. The mentioned principle applies to humans as well, although the critical period is longer. If the child does not receive any visual stimulation between the ages of eight and ten, it will result in blindness (2).

Cross-modal plasticity in the blind

The brain has the ability to efficiently reorganize and compensate for deficits in individuals with congenital or acquired absence of a sensory modality (10, 11). Blind individuals often demonstrate superior skills in their remaining senses compared to sighted individuals (12). Areas of brain deprived of dedicated sensory stimulation can be used by other sensory modalities. Sensory-specific areas such as visual cortex receive direct (short-latency) inputs from other sensory modalities (10). Many authors agree on visual cortex activation in the blind during Braille reading (13-20). In children with total congenital blindness, the visual cortex is redistributed to process tactile, spatial and somatosensory information, and even language (13).

Pascual-Leone et al. describe a two-step process after vision loss. Firstly, the established somatosensory and auditory connections to the visual cortex reveal themselves. Secondly, new connections are established and general long-term plastic reorganization occurs (7). Multiple pre-existing redundant pathways with the potential to take on similar function when needed may be the reason for cross-modal compensatory plasticity (21).

The brain has the ability to compensate for vision loss rapidly and reversibly. This similar cross-modal recruitment is seen in prolonged visual deprivation of sighted individuals (blindfolding for 90 minutes activates primary visual cortex during tactile discrimination tasks). The visual cortex of congenitally blind was researched in roughness or spatial distance discrimination of Braille dots during repetitive transcranial magnetic stimulation (rTMS). Results suggested that visual cortex preferentially processed macro-geometric information (spatial density). Its stimulation caused deficits in spatial discrimination, while somatosensory cortex stimulation preferentially disrupted roughness discrimination (micro-geometric judgment) (22). Similar findings were confirmed by Hamilton et al. They studied a congenitally blind woman who developed alexia for Braille after having sustained extensive bilateral lesions in her visual cortex caused by stroke (23). Despite an intact somatosensory cortex, injury of the visual cortex or temporary disruption by TMS impairs Braille reading ability (10).

The already developed visual network in early- and late-onset blindness performs perception for other senses but in congenital blindness, the visual network will develop and strengthen only if exposed to meaningful experiences and age-dependent activities, as well as modify other senses in compensation for blindness (14). Visual cortical pathways are recruited differentially not only in sighted and blind individuals but also in early and late blindness onset. This suggests that plastic reorganization and its range varies among populations (16).

New research implies the need for a new model of neuroplasticity since reorganization changes in late-onset blind and congenitally blind reach beyond visual cortex and cross-modal plasticity into multimodal or multi-sensory integration regions, where interconnectivity between visual regions and multimodal/heteromodal integration regions was increased in the mentioned groups compared to sighted controls (25).

Research

Burton et al. researched visual cortical activation in early blind, late blind and sighted participants during a vibrotactile matching task. Results showed the greatest activation of visual cortex in early blind and some activation in several of the late blind participants (early blind had better response magnitudes). The evidence supported the thesis of decreased plasticity in visual cortical regions with later onset age of blindness (26). A similar study agreed the congenitally and early-blind participants were better than the sighted ones on a vibrotactile discrimination task. Although in this research, duration of blindness did not predict task performance, congenitally blind participants were more accurate than the early-blind participants (12).

In sighted adults, a nine-month tactile Braille-reading training showed anatomical grey and white matter reorganization in the visual cortex, which is used for tactile discrimination of Braille characters, along with stronger functional connections to somatosensory and motor cortices (29). Also, activity in the visual cortex during blindfolded Braille reading and the visual word form area (VWFA) observed with whole brain fMRI was noticed, as well as resting-state functional connectivity increase between the VWFA and somatosensory cortex and bilateral decrease with other visual areas. TMS disruption of VWFA impaired the accuracy of Braille reading. The results implied cross-modal plasticity as a result of long-term training in cases without sensory deprivation and injury (30).

Does passive exposure to tactile stimuli in the blind result in increased visual cortex activity? Ortiz et al. studied visual cortex in blind teenagers and adolescents who had been exposed to passive tactile stimulation 3 hours per day for 3 months. The activity in visual cortex grew as the exposure continued. Although the stimuli in this research were not Braille dots but vertical, horizontal and oblique tactile lines, the study opens the question of similar passive program usefulness in later active tactile discrimination tasks and Braille reading ability (32).

Pascual-Leone and Torres associate reading Braille with the expansion of sensorimotor cortical representation of the reading finger. They came to this conclusion by studying the organization of the somatosensory cortex in proficient Braille readers, recording somatosensory-evoked potentials in blind and sighted subjects (33).

During Braille learning, neuroplastic changes happen because learners must acquire the ability to extract spatial information from subtle tactile stimuli. The sensorimotor cortical area devoted to representation of the reading finger enlarges. This enlargement suggests initial unmasking of the existing connections and establishment of more stable structural changes. In addition, Braille learning appears to be associated with recruitment of parts of the occipital cortex for tactile information processing. The occipital cortex can be critical for reading accuracy. Several studies suggest the possibility of applying noninvasive neurophysiologic techniques to guide and improve functional outcomes of these plastic changes, thus accelerating functional adjustment to blindness (34).

Ptito et al. stimulated the occipital cortex using single pulse transcranial magnetic stimulation in early blind subjects and blindfolded sighted control subjects. Some of the blind subjects felt tactile sensations in the fingers. The visual cortex was somatotopically organized for each finger. Blindfolded control subjects did not report any tactile sensations. Those who spent more hours per day reading Braille, as well as those who had better reading speed and dexterity reported more tactile sensations. A polysynaptic cortical pathway between the visual and somatosensory cortex may be responsible for these results (35).

Studies have shown greater plasticity in people with significant visual impairment than in those with a less significant visual impairment, although further research is needed to determine the effects of Braille reading training (1). Although various different methods (imaging, TMS, and psychophysiologic recordings) used in congenitally blind people have confirmed functional activation of the visual cortex, they have not extensively explained functional significance of these activation patterns (16).

Conclusion

Development of neuroscience has provided new information that is useful in rehabilitation, especially information about plasticity, brain areas and their functioning. Researchers have begun examining ways to harness neuroplasticity to promote healing and recovery. Changes in brain cell function occur throughout lifetime because of learning experiences and in response to nervous system injury. Visual stimuli are the main source of receiving information from our environment. Blind people use other senses to perceive their surroundings and this new usage implies anatomical (significant differences in volume and thickness of some brain regions) and functional (e.g., tactile stimuli while Braille reading activates visual cortex) changes. Evidence shows new neuron connections being formed in the visual cortex of people with patches over their eyes during an extended period of time, and disappearance of these connections after patch removal. As ever more is being learned about what causes neuroplasticity of the brain, we hope that new implications will be developed for educational and rehabilitation practitioners who work on developing Braille literacy in the visually impaired. Taking into account the potential for neuroplasticity in congenital, early- or late-onset vision loss, we can determine the range of success in learning Braille reading, which is important to create an individualized program for Braille literacy. The length, intensity and approach in the program need to be adjusted or they will discourage the student. A student who is prepared and knows what to expect is less likely to lose motivation during the literacy program.

References

2. Diamond M, Hopson J. Čarobno drveće uma: kako razvijati inteligenciju, kreativnost i zdrave emocije vašeg djeteta od rođenja do adolescencije. 2[ nd edn. Lekenik: Ostvarenje; 2006. (in Croatian) Google Scholar]

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16. Simon-Dack SL, Rodriguez PD, Teder-Sälejärvi WA. Psychophysiology and imaging of visual cortical functions in the blind: a review. Behav Neurol. 2008;20(3):71-81. 10.1155/2008/917492 [[ PubMed] [ CrossRef] PMC free article] [ Google Scholar]

25. Ortiz-Terán L, Ortiz T, Perez DL, Aragón JI, Diez I, Pascual-Leone A, et al. Brain plasticity in blind subjects centralizes beyond the modal cortices. Front Syst Neurosci. 2016. July;10(61):61. 10.3389/fnsys.2016.00061 [[ PubMed] [ CrossRef] PMC free article] [ Google Scholar]

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29. Bola Ł, Siuda-Krzywicka K, Paplinska M, Sumera E, Zimmermann M, Jednorog K, et al. Structural reorganization of the early visual cortex following Braille training in sighted adults. Sci Rep. 2017. December;7(1):17448. 10.1038/s41598-017-17738-8 [[ PubMed] [ CrossRef] PMC free article] [ Google Scholar]

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Articles from Acta Clinica Croatica are provided here courtesy of Sestre Milosrdnice University Hospital Center

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This article brings review of the studies and their findings about neuroplasticity of the brain and Braille reading, as well as some connections between the two. The goal of the article is to combine knowledge from different disciplines, thus enabling ...

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Ted Talk que nos revela como e porque devemos devemos “abraçar” a diversidade cultural.

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✒ Grupo: Bogdan; Sumaya; Filipe; Leonardo; Henrique

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A New Perspective on How, and Why, to Embrace Cultural Diversity | Lea Black | TEDxBismarck

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Estudo revela que pessoas com maior nível de educação tendem a recuperar mais facilmente de uma lesão cerebral traumática e de doenças degenerativas cerebrais.

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✒ Grupo: Bogdan; Sumaya; Filipe; Leonardo; Henrique

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College-educated people recover better from a brain injury

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College-educated people recover better from a brain injury, interesting anamoly that may be a clue to neuro-degeneration.

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Notícia onde é explicado o porquê de os atletas negros obtêm grandes resultados nos Jogos Olímpicos.

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✒Grupo: Bogdan; Sumaya; Filipe; Leonardo; Henrique

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The 2012 Olympics has again seen black athletes commanding the sprint events. For French journalist Jean-Philippe Leclaire, author of "Why Whites Run Slower", this dominance can be explained by a combination of the right genes and hard work.

Ever since American runner Jesse Owens took the 1936 Berlin Olympics by storm, black athletes have generally reigned supreme in the sprints at international tournaments.

The last 25 holders of the world record for the 100-metre race have all been black and data compiled in 2007 revealed that 494 out of the 500 best-ever 100-metre sprint times are held by athletes primarily of West African origin.

The lineup for Sunday's 100-metre final at London's Olympic stadium once again demonstrates the dominance of black sprinters.

Despite the glaring statistics, the topic was somewhat of a taboo subject until recent years. Most scientists, authors and journalists avoided any quest for an explanation out of a fear of being accused of racial stereotyping.

But, in 2010, French author Jean-Philippe Leclaire, a former editor in chief of popular French sports newspaper "L'Equipe", took it upon himself to examine the evidence. Inspired by the emergence of white French sprinter Christophe Lemaitre and by American author Jon Entine's book "Taboo: Why black athletes dominate sport and why we're afraid to talk about it", Leclaire decided to dedicate a year and a half of his life to breaking that taboo.
Breaking down stereotypes
He approached scientists, journalists and athletes, and travelled to Jamaica -- the homeland of sprint marvel Usain Bolt -- to find out why "black power" reigns supreme on the track. In June of this year, his findings and conclusions were published in "Why Whites Run Slower".

"I had been commissioned to write a biography of Usain Bolt at a time when Lemaitre became the first white athlete capable of running the 100-metre in under 10 seconds," Leclaire told FRANCE 24. Lemaitre's success on the track stirred the former athletics columnist to expand his mission slightly.

"Up to now, apart from Lemaitre and Australia's Patrick Johnson, all the sprinters who have run the 100-metre in under 10 seconds were either born in West Africa or were descendants from slaves from West Africa," he said.

"Lemaitre broke down all the prejudices and stereotyping, so I decided to write a book to raise the debate around this issue," he said.

Over 361 pages, Leclaire examined the link between sporting performance and country of origin.

He studied a range of existing theories, including one that points to the so-called "innate muscle" makeup of black sprinters and another that argues that the supposed greater length of Kenyan runners' femurs gave them an advantage. Other arguments revolved around the apparent thinner skin and lighter internal organs of black athletes.

In a 2010 study, two American academics insisted that black athletes' dominance of the sport was down to their higher centre of gravity.

The legacy of slavery and the need to escape poverty are also more controversial theories that have come and gone.
Sprinting gene

By the end of his research, Leclaire was left in no doubt. For him, "athletic performance is largely determined by genetics and specifically ACTN3, the so-called 'sprint gene'".

The ACTN3 was discovered for the first time by a team of Australian researchers in 2003. It is a gene present in all humans in two forms, either the RR form which helps speed, or the RX form which aids endurance.

"Since its discovery, a lot of research has shown that the RR form of the gene gives those who hold it explosive muscle power when the body is put under a certain amount of physical stress, so it's a natural predisposition for sprinters," Leclaire explained.

"If you had a weak form of ACTN 3, it would be impossible to match the great sprinters," he said.

Leclaire concluded that the genes favourable for sprinting are more commonly found in those of West African origin.

There are exceptions, of course, which explains how French sprinter Lemaitre has been able to compete in the same class as the likes of Bolt and fellow Jamaican sprinter Yohan Blake.

"Lemaitre posesses the same genetic combinations that you find in most of the athletes of West African origin. He is the exception that confirms the rule," Leclaire said.

East Africa, by contrast, is the land of the long-distance runner.

Author John Entine believes genetics also explains the continuing supremacy of Kenya's runners in long distance races.

"They are short and slender with huge natural lung capacity and a preponderance of slow twitch muscles, the energy system for endurance sports," Entine wrote on the website blackathlete.net. "It's a perfect biomechanical package for long-distance running but a disaster for sports that require anaerobic bursts of speed."
It's not all biological
However, anyone thinking that they'll able to challenge Usain Bolt at the London Olympics just because they possess the ACTN3 gene can forget it.

"Sociocultural factors also come in to play," said Leclaire. "And it's also a question of personality. Jessie Owens, Tommie Smith, Marie-Jose Perec and Usain Bolt became who they are thanks to training and the choices they have made as well as their genetic makeup."

The director of the Copenhagen Muscle Research Institute, Bengt Saltin, believes an athlete's "environment" can account for 20 to 25 percent of his speed, but that the rest is down to birth.

Some of the many scientists and authors who have broached the issue in recent years preach caution about a tendency to fall into the trap of racially stereotyping athletes.

Matthew Syed, author of the book "Bounce: The Myth of Talent and the Power of Practice" points out that a host of West African countries including Ivory Coast, Senegal, Congo and Angola have never produced an Olympic sprint champion.

"Just because some black people are good at something does not imply that black people in general will be good at it," Syed told the BBC.

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French book examines why black sprinters dominate the Olympics

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The 2012 Olympics has again seen black athletes commanding the sprint events. For French journalist Jean-Philippe Leclaire, author of "Why Whites Run Slower", this dominance can be explained by a combination of the right genes and hard work.

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Elementos culturais que constituem o padrão de cultura portuguesa 

# data[].attributes.subject
Elementos culturais que constituem o padrão de cultura portuguesa 

# data[].attributes.body
Coisas que definem Portugal (elementos principais)

Grupo: Diana Sousa, Margarida, Rita, Rafael M. e Tomás

# data[].attributes.headline
Elementos culturais que constituem o padrão de cultura portuguesa 

# data[].attributes.subject
Elementos culturais que constituem o padrão de cultura portuguesa 

# data[].attributes.body
Como são os portugueses?

Grupo: Diana Sousa, Margarida, Rita, Rafael M. e Tomás

# data[].attributes.headline
Comparação entre o padrão de cultura da sociedade portuguesa antes e depois do 25 de Abril

# data[].attributes.subject
Comparação entre o padrão de cultura da sociedade portuguesa antes e depois do 25 de Abril

# data[].attributes.body
Grupo: Bruna Diogo, n.º 3; Diogo Pires, n.º 6; Guilherme Alves, n.º 11; Nina Menezes, n.º 19; Rafael Sousa, n.º 20.

https://youtu.be/-SV1EBNYup8
https://youtu.be/MOFrjP8bX_c

# data[].attributes.headline
Comparação entre o padrão de cultura da sociedade portuguesa antes e depois do 25 de Abril

# data[].attributes.subject
Comparação entre o padrão de cultura da sociedade portuguesa antes e depois do 25 de Abril

# data[].attributes.body
Grupo: Bruna Diogo, n.º 3; Diogo Pires, n.º 6; Guilherme Alves, n.º 11; Nina Menezes, n.º 19; Rafael Sousa, n.º 20.