Scientists use fossils to study earth history by identifying the fossil and what era it came from. By knowing what era the fossil came from and what location it was found, scientists can make assumptions about the earth formation at that time.
Variation and natural selection
<span>The reserves will eventually be used up. </span>
Androgen hormone is the primary determinant of whether a baby will develop male or female external genitalia.
Androgen is usually a steroid hormone. The predominant and most active androgen in testosterone, which is produced by the male testes. Some androgens are naturally produced in the body and if the body doesn't make them properly they can be obtained through prescription medication.
