Name the Artist: Come A Little Bit Closer?

Questions

---------- were domesticated around 4,000 years ago.?

Camels were used as pack animals in ---------- and Arizona as late as 1870.?

The hippopotamus gives birth ---------- and nurses its young in the river as well, although the young hippos must come up periodically for air.?

The hippopotamus has skin an inch-and-a-half thick, so solid that most ---------- cannot penetrate it.?

The average life expectancy of a leopard in captivity is ----------?