Readers ask about bird droppings, Ice Age cave art, and more

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Bodily waste is actually pretty cool

Mucus bubbles may help cool the short-beaked echidna by coating the creature’s nose with moisture, which evaporates and draws heat from the blood-filled sinuses, helping to cool the blood, Elise Cutts mentioned inSpike’s cool balls beat the heat with snot bubbles(SN: 2/11/23, p. 32).

Other animals also have creative ways of using fluids to stay calm. Some birds, for example, urinate on themselves to survive the hot days. Katz books. reader James Wilson He noted that the word “pee” could be misleading, since bird droppings are usually a mixture of urine and feces.

It is true that bird droppings are a mixture of urine and feces that pass through a single opening called the cloaca. So the term “excretory” might be more appropriate, says the ornithologist Julian Capello Virgil from the University of Extremadura in Badajoz, Spain. For birds that cool off by dropping waste, a phenomenon called urohidrosis, the liquid component of bird droppings is key. When storks, herons, boobies and some other species of birds excrete juicy droppings on their legs, “it is the evaporation of the water in the droppings that results in heat loss from [body] on the environment,” Capello Virgil He says.

When gene flow slows down

About 20 to 50 percent of the DNA of modern forest birds comes from domesticated chickens due to interbreeding, which threatens the genetic diversity and long-term survival of wild birds, which live in South and Southeast Asia, Jake Buehler mentioned inChicken DNA is running out in wild birds(SN: 2/11/23, p. 14).

reader Van Snyder He was asked if wild forest birds pass any of their genetic material on to chickens.

evolutionary biologist Frank Rindt He has “no doubt that the gene flow between domestic chickens and wild forest fowl is bi-directional.” It is likely that many local village chickens in South and Southeast Asia are regularly exposed to genes from the wild red forest fowl they encounter near village-forest boundaries.

But the flow of genetic material from wild red forest fowl to chickens in general will be marginal, he says Reindt, from the National University of Singapore. “The vast majority of domestic chickens are battery chickens kept in airtight enclosures, mostly outside of tropical Asia, and these chickens will remain unaffected.”

Definition of depression

Depression is often attributed to a chemical imbalance in the brain. In fact, scientists do not have a good explanation for what depression is or what causes it, despite decades of research. Laura Sanders mentioned inThere are no simple answers(SN: 2/11/23, p. 18).

Many readers appreciated it Sanders reports.

“It is a wonderful example of popular science writing for an audience about an urgent and difficult issue of human suffering,” said the reader R. Michael Johnson books. “I am particularly touched and delighted by your assurances that depression is not a one-size-fits-all, and that geographic/cultural differences should not be underestimated.”

Why “Y”?

Pleistocene hunter-gatherers may have used cave art to track the mating and birthing seasons of local animals, Anna Gibbs mentioned inIce Age cave art may serve as a calendar(SN: 2/11/23, p. 16). For example, the “Y” symbols in art could refer to childbirth, the researchers believe.

reader Richard Delaware He wondered why the “Y” symbol had developed this meaning.

“Maybe we’ll never know,” he says. Ben Bacon, an independent researcher based in London who helped decipher cave art. One possible explanation could be that the symbol represents the female pubic region. In Paleolithic art, including small carved figurines and wall paintings, this area was often depicted with a clear Y-shaped outline, bacon He says.

Another possible explanation is based on the fact that the symbol is a line that splits in two. “One becomes two, which perfectly describes the process of giving birth,” bacon speculate.

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