Earth formed around 4.54 billion years ago by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere and then the ocean; but the atmosphere contained almost no oxygen and so would have been toxic to most modern life including humans.
Euthyroid is the state of having normal thyroid gland function. Examples of a nonfunctioning thyroid gland may be hypothyroidism, hyperthyroidism, or thyroiditis.
Euthymia (medicine) Euthymia is a normal non-depressed, reasonably positive mood. It is distinguished from hyperthymia, which refers to an extremely happy mood, and dysthymia, which refers to a depressed mood. It is a term used frequently in mental status exams.