1850s: Great Britain is the world's political and economic leader.

Today: Since the fall of the Soviet Union in 1991, America is the single remaining superpower in the world.

1850: Most of the world is agricultural. The following year, Britain becomes the first nation in the world to have the majority of its population living in cities.

Today: Most of the world's population is clustered into cities and their surrounding suburbs.

1850s: Life expectancy in Great Britain is between 43 and 47 years. Tennyson lived almost twice this, though his friend Arthur Hallam, memorialized in this poem, lived less than half the average.

Today: The average life expectancy for men in Great Britain is 75 years old; for women, it is 80.

1850s: Tea outsells coffee for the first time in Great Britain, due in large part to the introduction of a new custom, afternoon tea, ten years earlier.

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