Main articles: Growth hormone 1 and Growth hormone 2. Genes for human growth hormone, known as growth hormone 1 (somatotropin) and growth hormone 2, are localized in the q22-24 region of chromosome 17 and are closely related to human chorionic somatomammotropin (also known as placental lactogen) genes.
The U-shape of the marginal cost curve is directly attributable to increasing, then decreasing marginal returns (and the law of diminishing marginal returns). As marginal product (and marginal returns) increases for relatively small output quantities, marginal cost declines.
While the shape of the long-run marginal cost curve looks surprisingly like that of a short-run marginal cost curve, the underlying forces are different. This U-shape is NOT the result of increasing, then decreasing marginal returns that surface in the short run when a variable input is added to a fixed input.ot the Short Run. 1  The Short Run: In the short run, marginal cost decreases due to increasing marginal returns and increases due to decreasing marginal returns and the law of diminishing marginal returns. 2  This also triggers changes in average cost (variable and total).