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.The negatively-sloped portion of this long-run marginal cost curve reflects economies of scale and increasing returns to scale. Long-run Average Cost: This curve graphically illustrates the relation between long-run average cost, which is the per unit cost incurred by all of the factors of production used in the long run by a firm to produce a good or service, and the level of production.