Aging is associated with a loss of sensitivity to

a. higher intensity sounds

The fact that humans are more motivated to protect the children of their siblings and kin than the children of strangers is explained by _________

Fill in the blank(s) with the appropriate word(s).

In the United States and Canada, postpartum blues

a. are experienced by about half of women who have recently given birth. b. usually last about two weeks. c. are most common in women who have already had two or more children. d. is another term for postpartum depression.