Concept explainers
Human Adaptation to a Starchy Diet The human AMY-1 gene encodes salivary amylase, an enzyme that breaks down starch. The number of copies of this gene varies, and people who have more copies generally make more enzyme. In addition, the average number of AMY-1 copies differs among cultural groups.
George Perry and his colleagues hypothesized that duplications of the AMY-1 gene would be selectively advantageous in cultures in which starch is a large part of the diet. To test this hypothesis, the scientists compared the number of copies of the AMY-1 gene among members of seven cultural groups that differed in their traditional diets. FIGURE 39.9 shows their results.
FIGURE 39.9 Number of copies of the AMY-1 gene among members of cultures with traditional high-starch or low-starch diets. The Hadza, Biaka, Mbuti, and Datog are tribes in Africa. The Yakut live in Siberia.
None of the Mbuti (rain-forest hunter–gathers) had more than 10 copies of AMY-1. Did any European Americans?
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Biology: The Unity and Diversity of Life (MindTap Course List)
- Human Adaptation to a Starchy Diet The human AMY-1 gene encodes salivary amylase, an enzyme that breaks down starch. The number of copies of this gene varies, and people who have more copies generally make more enzyme. In addition, the average number of AMY-1 copies differs among cultural groups. George Perry and his colleagues hypothesized that duplications of the AMY-1 gene would be selectively advantageous in cultures in which starch is a large part of the diet. To test this hypothesis, the scientists compared the number of copies of the AMY-1 gene among members of seven cultural groups that differed in their traditional diets. FIGURE 39.16 shows their results. FIGURE 39.16 Number of copies of the AMY-1 gene among members of cultures with traditional high-starch or low-starch diets. The Hadza, Biaka, Mbuti, and Datog are tribes in Africa. The Yakut live in Siberia. 1. Starchy tubers are a mainstay of Hadza huntergatherers in Africa, whereas fishing sustains Siberia's Yakut. Almost 60 percent of Yakut had fewer than 5 copies of the AMY1 gene. What percentage of the Hadza had fewer than 5 copies?arrow_forwardHuman Adaptation to a Starchy Diet The human AMY-1 gene encodes salivary amylase, an enzyme that breaks down starch. The number of copies of this gene varies, and people who have more copies generally make more enzyme. In addition, the average number of AMY-1 copies differs among cultural groups. George Perry and his colleagues hypothesized that duplications of the AMY-1 gene would be selectively advantageous in cultures in which starch is a large part of the diet. To test this hypothesis, the scientists compared the number of copies of the AMY-1 gene among members of seven cultural groups that differed in their traditional diets. FIGURE 39.9 shows their results. FIGURE 39.9 Number of copies of the AMY-1 gene among members of cultures with traditional high-starch or low-starch diets. The Hadza, Biaka, Mbuti, and Datog are tribes in Africa. The Yakut live in Siberia. Do these data support the hypothesis that a starchy diet favors duplications of the AMY-1 gene?arrow_forwardA contributing factor to the development of arthritis is the inappropriate proteolytic destruction of the aggrecan component of cartilage by the proteolytic enzyme aggrecanase. The immune system signal molecule interleukin 2 (IL-2) activates aggrecanase; in fact, IL-2 blockers are sometimes used to treat arthritis. Studies were undertaken to determine whether inhibitors of aggrecanase could counteract the effects of IL-2. Pieces of cartilage were incubated in media with various additions and the amount of aggrecan destruction was measured as a function of time. Aggrecan degradation was measured by the release of glycosaminoglycan. What is the rationale for this assay? Aggrecan is a transferase enzyme that adds glycosaminoglycans to glycoproteins, and these glycosaminoglycans remain free if aggrecan is degraded. Aggrecan is a lectin that binds glycosaminoglycan ligands, and aggrecan releases these glycosaminoglycans as it is degraded. Aggrecan inhibits the removal of glycosaminoglycans…arrow_forward
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