Since its discovery about 60 years ago, one of the earliest stone monuments in the history of humankind, a tower on the western edge of the ancient settlement of Tel Jericho, has inspired a number of theories about why it was built.
Now, after studying how the sun setting on the summer solstice, the longest day of the year, interacted with the tower and the landscape around it, two archeologists from Tel Aviv University have concluded the 28-foot (8.5 meter) tower symbolized power and might.
"We suggest that the tower was built not just as a marker or a time-keeping device, but as a guardian against the dangers present in the darkness cast by a dying sun's last rays of light," write the researchers, Roy Liran and Ran Barkai, in the journal Antiquity. (After the summer solstice, the nights begin to grow longer.)
Their reconstruction revealed that, as the solstice sun set, the shadow of a hill to the west fell exactly on the Jericho tower before covering the village, suggesting the monument and the start of longer nights were linked.
The people who built this tower approximately 11,000 years ago were settled hunter-gatherers on the threshold of the transition to agriculture. Unlike their ancestors, they could no longer pack up and leave in times of danger or uncertainty.
The tower's construction may be related to the primeval fears and cosmological beliefs of the villagers, the archaeologists speculate, though they have no scientific evidence of such.
"This was a time when hierarchy began and leadership was established," Barkai told the Jerusalem Post. "We believe this tower was one of the mechanisms to motivate people to take part in a communal lifestyle."
Others have theorized that the tower and a wall beside it were fortifications to protect the settlement, a defense against flooding, a geographical marker or a symbol of wealth.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.