Answer to Question 1
Answer: Research on handedness, along with other evidence, supports the joint contribution of nature and nurture to brain lateralization. Handedness reflects the greater capacity of one side of the brainthe individuals dominant cerebral hemisphereto carry out skilled motor action. Other important abilities are generally located on the dominant side as well. For right-handed peoplein Western nations, 90 percent of the populationlanguage is housed in the left hemisphere with hand control. For the left-handed 10 percent, language is occasionally located in the right hemisphere or, more often, shared between the hemispheres. This indicates that the brains of left-handers tend to be less strongly lateralized than those of right-handers.
Heritability of left-handedness is weak to modest. Left-handed parents have only a mildly elevated chance of having left-handed children. This suggests a genetic bias favoring right-handedness that experiences can overcome, swaying children toward a left-hand preference.
Handedness also involves practice. It is strongest for complex skills requiring extensive training, such as eating with utensils, writing, and engaging in athletic activities. And wide cultural differences exist. For example, in tribal and village cultures, the rates of left-handedness are relatively high. But in a study of one such society in New Guinea, individuals who had attended school in childhood were far more likely to be extremely right-handedfindings that highlight the role of experience.
Answer to Question 2
Answer: B
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