Why do glaciologists study ice cores?

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -

Which hormone is used by both males and female?

All annelids and arthropods have a blank body plan . unlike annelids, arthropods also have blank . the circulatory system of annelids is blank , while circulatory system of arthropods is blank .