Hypothyroidism results from deficient production of thyroid hormone or a defect in the thyroid hormone receptor activity. hypothyroidism caused during embryonic development of the gland is called:

hyperthyroidism—an abnormally elevated blood level of thyroid hormones—is often caused by a pituitary or thyroid tumor. In Graves' disease, the hyperthyroid state results from an autoimmune reaction in which antibodies overstimulate the follicle cells of the thyroid gland.

the fossil record provides evidence of a common ancestor to many species.