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Falcon fidelity and latrine archaeology

by Michael Torrice
August 8, 2016 | A version of this story appeared in Volume 94, Issue 32


Faithful falcons in the city


Credit: John W. Iwanski
New in town: Peregrine falcons stay loyal to their mates even after moving to cities such as Chicago.
Photograph of peregrine falcon in Chicago.
Credit: John W. Iwanski
New in town: Peregrine falcons stay loyal to their mates even after moving to cities such as Chicago.

Moving to a big city can change a person. Newcomers bump into novel experiences and opportunities and pick up new habits and perspectives.

A team of biologists wanted to see if this was true for peregrine falcons that started living in Midwest cities over the past few decades. In particular, they wondered whether the birds strayed from mating monogamously.

The researchers’ results should warm the heart of even the most cynical Newscripts reader: The city-dwelling falcons remain faithful despite their new urban digs (PLOS One 2016, DOI: 10.1371/journal.pone.0159054).

Early in the last century, peregrine falcons lived in cliffs and bluffs along the Mississippi River. But by the mid-1960s, there were no more falcons in the Midwest because of the effects of the pesticide DDT.

Starting in the 1980s, scientists tried to repopulate these majestic birds by breeding falcons from other parts of the world and releasing them into cities such as Chicago.

When Isabel C. Caballero was a graduate student at the University of Illinois, Chicago, she and three other researchers noticed that the birds were nesting closer to each other than they would in more traditional environments. The closer nests increased competition for mates and nesting sites. So did this competition increase infidelity?

“Basically, we did paternity tests,” says Caballero, who is now a postdoc at Texas A&M University. Her colleagues collected blood samples from chicks in nest boxes on city buildings, sometimes sporting helmets for protection. “Falcons sometimes punch you in the head,” Caballero says.

On the basis of genetic analyses of 350 peregrine falcons from nine Midwest cities between 1997 and 2009, the team determined that rates of infidelity were low: They observed just 12 mate changes and six nest changes.

Caballero points out that falcon mates are not only faithful, but they also share hunting and egg-incubating duties: “You could say that the falcons are pretty modern in the sense that the males and females share responsibilities,” she says.

Toilet paper on the Silk Road


Credit: Hui-Yuan Yeh
2,000-year-old hygiene: Cloth wrapped around these bamboo sticks was the toilet paper of its time.
Photographs of personal hygiene sticks.
Credit: Hui-Yuan Yeh
2,000-year-old hygiene: Cloth wrapped around these bamboo sticks was the toilet paper of its time.

For more than 1,000 years, starting around the 2nd century B.C.E., people and goods traveled along the Silk Road, a collection of trade routes that connected China and East Asia with the Middle East and Europe. Now, researchers report the first direct evidence that these routes also passed pathogens between East and West.

The critical clue: a 2,000-year-old equivalent of toilet paper.

Anthropologists have long thought that diseases such as anthrax, leprosy, and bubonic plague traveled to Europe via the Silk Road, says Piers D. Mitchell of the University of Cambridge.

Mitchell studies the history of human migration and the diseases that follow people. To do so, he often looks for parasites at archeological sites. Unlike pathogens, such as the tuberculosis bacterium, that spread directly from person to person, some parasites require living in certain animals for part of their life cycles. If those animals only live in certain places, then scientists can pinpoint the parasite’s geographic origin.

In the 1990s, Chinese archeologists excavated a relay station along the Silk Road at Xuanquanzhi in northwestern China. In a latrine, the archeologists found sticks wrapped in cloth. People used these “personal hygiene sticks” to wipe themselves after defecating.

Because this region is arid, the sticks hadn’t decomposed much. “You still have the cloth around the ends and feces on the cloth,” Mitchell says.

When the team analyzed feces samples from the sticks using light microscopy, they found eggs from four different parasite species (J. Archaeol. Sci. Rep. 2016, DOI: 10.1016/j.jasrep.2016.05.010). One, Chinese liver fluke, is found only in wet, marshy areas of Korea and eastern China, a sign that some traveler carried the parasite at least 1,500 km to Xuanquanzhi.

Michael Torricewrote this week’s column. Please send comments and suggestions to


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