A ‘mystery monkey’ in Borneo may be a rare hybrid. That has scientists worried

Six years ago, tour guide Brenden Miles was traveling down the Kinabatangan River in the Malaysian part of Borneo, when he spotted an odd-looking primate he had never seen before. He snapped a few pictures of the strange monkey and, on reaching home, checked his images.

“At first, I thought it could be a morph of the silvered leaf monkey,” meaning a member of the species with rare color variation, Miles says. But then he noticed other little details. “Its nose was long like that of a proboscis monkey, and its tail was thicker than that of a silvered leaf [monkey],” he says. He posted a picture of the animal on Facebook and forgot all about it.

Now, an analysis of that photo and others suggests that the “mystery monkey” is a hybrid of two distantly related primate species that share the same fragmented habitat.
The putative offspring was produced when a male proboscis monkey (Nasalis larvatus) mated with a female silvered leaf monkey (Trachypithecus cristatus), researchers suggest April 26 in the International Journal of Primatology. And that conclusion has the scientists worried about the creature’s parent species.

Hybridization between closely related organisms has been observed in captivity and occasionally in the wild (SN: 7/23/21). “But hybridization across genera, that’s very rare,” says conservation practitioner Ramesh Boonratana, the regional vice-chair for Southeast Asia for the International Union for Conservation of Nature’s primate specialist group.

Severe habitat loss, fragmentation and degradation caused by expanding palm oil plantations along the Kinabatangan River could explain how the possible hybrid came to be, says primatologist Nadine Ruppert.

“Different species — even from the same genus — when they share a habitat, they may interact with each other, but they may usually not mate. This kind of cross-genera hybridization happens only when there is some ecological pressure,” says Ruppert, of the Universiti Sains Malaysia in Penang Island.

The state of Sabah, where Kinabatangan River is located, lost about 40 percent of its forest cover from 1973 to 2010, with logging and palm oil plantations being the main drivers of deforestation, a study in 2014 found.
“In certain areas, both [monkey] species are confined to small forest fragments along the river,” Ruppert says. This leads to competition for food, mates and other resources. “The animals cannot disperse and, in this case, the male of the larger species — the proboscis monkey — can easily displace the male silvered leaf monkey.”

Since 2016, there have been some more documented sightings of the mystery monkey, though these have been sporadic. The infrequent sightings and the COVID-19 pandemic has, for now, prevented researchers from gathering fecal samples for genetic analysis to reveal the monkey’s identity. Instead, Ruppert and colleagues compared images of the possible hybrid with those of the parent species, both visually as well as by using limb ratios. “If the individual was from one of the two parent species, all its measurements would be similar to that of one species,” Ruppert says. “But that is not the case with this animal.”

A photograph of a male proboscis monkey mating with a female silvered leaf monkey, along with anecdotes from boat operators and tour guides about a single male proboscis monkey hanging around a troop of female silvered leaf monkeys, has added further weight to the researchers’ conclusion.

The mystery monkey is generating a lot of excitement in the area, but Ruppert is concerned for the welfare of both proposed parent species. The International Union for Conservation of Nature classifies proboscis monkeys as endangered and silvered leaf monkeys as vulnerable. “The hybrid is gorgeous, but we don’t want to see more of them,” Ruppert says. “Both species should have a large enough habitat, dispersal opportunities and enough food to conduct their natural behaviors in the long term.”

Increasing habitat loss or fragmentation in Borneo and elsewhere as a result of changing land uses or climate change could lead to more instances of mating — or at least, attempts at mating — between species or even genera, Boonratana says.

The mystery monkey was last photographed in September of 2020 with swollen breasts and holding a baby, suggesting that the animal is a fertile female. That’s another surprising development, the researchers say, because most hybrids tend to be sterile.

Pressure to conform to social norms may explain risky COVID-19 decisions

The pandemic has entered a murky stage, and social norms are quickly shifting, something I’ve thought a lot about lately. Many people are testing at home, or not at all. Here in Vermont, where I live, you can pick up a type of PCR test that can be taken at home. But state officials both here and elsewhere are no longer carefully monitoring the results of these tests, which means that the actual spread of coronavirus in the U.S. population remains unclear (SN: 4/22/22).

For a few weeks, rumors of a stealth COVID-19 wave have been circulating both in the media and on my Twitter feed. Now cases and hospitalizations are rising, as are the levels of coronavirus in wastewater. That suggests that more cases, and ultimately deaths, could follow.
Even with rising caseloads and a vaccination rate that has flatlined at about 66 percent of the eligible population, the American public has largely begun to move on from the COVID-19 crisis. People are shedding their masks, eating out, attending concerts, traveling to far-flung locations, having large, indoor weddings and doing all the social things that people tend to do when left to their own devices.

The 2,600-person White House Correspondents’ Association dinner late last month is a case in point. Just as host Trevor Noah prophesied, many of those in attendance have since tested positive for COVID-19, including U.S. Secretary of State Antony Blinken and reporters from NBC, ABC, the Washington Post, Politico and other media outlets. And those who almost certainly knew better — cue White House Coronavirus Response Coordinator Ashish Jha — nonetheless made an appearance.

Myriad quirks related to human behavior undoubtedly underpin these arguably poor choices. The Decision Lab website has a list of the biases and mental shortcuts people use to make decisions. The one that caught my eye is social norms. This particular quirk outlines what behaviors people deem appropriate in a given situation.

I started thinking about social norms while writing a feature on how to get people in the United States to eat less meat when the practice is so, well, normal (SN: 5/11/22). Social norms, my research informed me, vary with the group one is hanging out with and one’s environs. “We rapidly switch our perspective depending on the context of the situation we find ourselves in,” writes marketing expert John Laurence on the Decision Lab site.

I might have found this idea of rapid switching suspect had I not recently experienced the phenomenon. My husband’s Disney-phile brother and his wife had been planning a family reunion in Disney World in Florida since the start of the pandemic. And I, a curmudgeonly sort not prone to feeling the magic, long ago agreed to go on the condition that other people do all the planning. And so it was, after multiple COVID-related postponements, that my kids, my husband and I landed in Orlando on a blisteringly hot April day.

Disney normal, I soon learned, bore little resemblance to Vermont normal. This was obvious immediately from people’s attire. All around me parents and kids dressed in coordinated outfits and matching Mickey Mouse ears. (Apologies to my kids — your mom missed the fashion memo.)
Social norms almost certainly arose to foster cohesion among our earliest ancestors, who needed solidarity to hunt large prey, share limited resources and ward off predators and enemy tribes. In-group norms also provide humans with a sense of belonging, which research suggests is vital for our overall health. A meta-analysis of more than 3.4 million people followed for an average of seven years showed that the likelihood of dying during the study period increased by 26 percent for participants who reported feeling alone (SN: 3/29/20).

Not surprisingly, then, one of the strongest drivers of human behavior is to seek out belonging. At Disney, that quest means blocking out the reality that exists just outside the fiefdom. Wars, climate crises, political fighting and the like have no place within those magical walls. Nor do reminders of a global health crisis that, according to the latest World Health Organization estimates, has thus far killed nearly 15 million people worldwide.

Within Disney’s walls, throngs of mostly maskless tourists packed onto iconic rides and into restaurants. When halfway through our trip, a Florida judge ruled that masks could not be mandated on public transit, nary a mask was to be seen on buses shuttling people to the Magic Kingdom and Epcot Center. And everywhere, all the time, people seemed to be coughing, sniffling or blowing their noses.

As a science reporter covering COVID-19, I certainly knew that I should keep my mask on. And yet, my resolve soon faltered. My kids pointed out that no one else was masking, not even my typically rule-following relatives. Donning my mask meant confessing that I was not reveling in the sparkle and glitz and magic and making all too obvious to my beloved extended family that I did not, in fact, belong. I kept my face covering in my pocket.

Humans’ tendency toward conformity is not all bad. In a now classic study from the 1980s, researchers investigated how to reduce water consumption in drought-prone California. Signs at the University of California, Santa Cruz asking students to turn off the shower while soaping up led to only 6 percent compliance. So researchers recruited male students to serve as norm-setting role models. These role models would hang out in the communal shower until they heard another student come in, and then soap up with the water off. When one role model soaped with the shower off, roughly half of the unwitting students also began turning off their faucets at soaping time. Compliance jumped to 67 percent when two role models followed the sign.

But conformity can also distort how we make decisions. For instance, in the summer of 2020, when the pandemic was still new, researchers asked 23,000 people in Mexico to predict how a fictional woman named Mariana would decide whether or not to attend a birthday party. Most participants believed Mariana should not attend. But when they read a sentence suggesting her friends would attend or that others approved of the party, their predictions that Mariana would also go increased by 25 percent, researchers reported in PLOS ONE.

My decision to conform to Disney normal ended predictably — with a positive COVID-19 test. After weeks of coughing and sleepless nights, though, my frustration is less directed at myself than at political leaders who so blithely ignore both epidemiology and human behavior research and tell us to live like it’s 2019. It’s not. Nor is it 2020 or 2021. It’s the murky year known as 2022. And the rules of behavior that bolster our social norms — such as role models who refrain from large, indoor, unmasked gatherings, and leaders who uphold mask mandates on public transit to protect the most vulnerable — should reflect this liminal space.

Here’s why pipe organs seem to violate a rule of sound

A speck of gold dancing to a pipe organ’s tune has helped solve a long-standing mystery: why certain wind instruments violate a mathematical formula that should describe their sound.

In 1860, physicist Hermann von Helmholtz — famous for his law of the conservation of energy — devised an equation relating the wavelength of a pipe’s fundamental tone (the lowest frequency at which it resonates) to pipe length (SN: 3/31/28). Generally, the longer a pipe is, the lower its fundamental tone will be.

But the equation doesn’t work in practice. A pipe’s fundamental tone always sounds lower than the pipe’s length suggests it should according to Helmholtz’s formula. Fixing this problem requires adding an “end correction” to the equation. In the case of open-ended pipes such as flutes and those of organs, the end correction is 0.6 times the radius of the pipe. Why this was, nobody could figure out.

A break in the case came in 2010. Instrument builder and restorer Bernhardt Edskes of Wohlen, Switzerland was tuning an organ when he spotted a piece of gold that had come loose from a pipe’s gilded lip. Air pumping through the pipe should have carried away the gold. Instead, it seemed to be trapped in a vortex just above the pipe’s upper rim.

Edskes told his friend, physicist Leo van Hemmen of the Technical University of Munich, about the observation. Together with colleagues from Munich and Wageningen University in the Netherlands, they studied how air moves through playing organ pipes using cigarette smoke.

When an organ pipe sounds, a vortex indeed forms over the pipe’s rim, the team reported March 14 in Chicago at a meeting of the American Physical Society. What’s more, this vortex is capped by a hemisphere of resonating air.
This vibrating air cap, van Hemmen says, is the long-sought explanation for the “end correction.” The cap effectively lengthens the organ pipe by the exact amount that must be tacked on to Helmholtz’s formula to explain the pipe’s fundamental tone.