SAMPLINGS An Early Gut-Brain Connection An artist’s rendering of Ikaria researchers concluded that I. Scientists have long known that the brain—specifically an area Bilaterian wariootia, a 555-million-year- wariootia would have lived on known as the brain stem—controls involuntary bodily func- Most modern animals follow the old wormlike organism a shallow prehistoric seafloor. tions, such as breathing and digestion. But a recent study of the same basic body plan: openings These rock layers also contain gut-brain relationship suggests that processing for gut func- at either end connected by a tiny fossilized burrows that the tions occurs in more regions of the brain than was previously continuous gut. The emergence scientists contend I. wariootia understood. The study reveals a “road map” of pathways that of animals with this blueprint, created as it scooted beneath connect the gut to parts of the brain responsible for emotion bilaterians, marked a major a light blanket of sand, likely and complex thought. development in the evolution of scavenging for organic matter. Artist’s renditionA phage of a newlyshell discovered low-mass black Neuroscientists at the University of Illinois at Urbana- animal life. Biologists had pre- These abilities to scavenge and (right) latches Champaign studied the gut-brain connection in rats. They in- dicted that the earliest bilaterian displace sediment imply that I. hole (left)-giantonto star and (right) inhibits jected the small intestines with viruses that infect nerve cells. would be simple and small. But wariootia had simple sensory binary systemproteins on the These viruses served as tracers, traveling along the same neuro- because it would have had a soft organs in addition to a mouth, influenza virus nal pathways that a sensory signal would. Fluorescent proteins body, finding evidence of it in through-gut, and anus. in this artist’s visualization. attached to the viruses allowed the scientists to trace the path a the fossil record seemed unlike- The team speculates, virus traveled through the body to the brain. ly. However, an international but cannot confirm, that I. Over five days, the researchers watched as tracers made their team has uncovered fossils of SOHAIL WASIF/UCR wariootia may be the earliest way through sensory nervous systems. The fluorescent markers an ancient, wormlike organism rock layer estimated to be 555 exhibited the hallmarks of a ancestor of bilaterians. “The Virus Bait revealed connections between the gut and several different parts that could fit the bill. million years old. These fossils bilaterian. One end of the fossil fossil record only captures a Current drug treatments for influenza have limited effective- of the brain, including the brainstem. Signals from the gut also During his doctoral research were too small to examine in tapered to a point, while the fraction of the life that existed ness because they attack the virus after it infects lung cells. In traveled to the amygdala, known for processing emotion, and the at the University of California detail with standard tools, such other was wider and rounder. on Earth, and we caught a pre-clinical laboratory trials, however, a research team based cortex, which handles such complex processes as memory and Riverside, paleontologist Scott as photographs and rubber The team determined that very small but important part in Berlin, Germany, has demonstrated a promising method for attention. D. Evans and his advisor, Mary molds. A three-dimensional la- the organism represented a dis- of that history,” said Evans,

BARTH VAN ROSSUM, FMP VAN BARTH combating infection by blocking the virus before it invades lung More research is needed to determine if this finding applies Droser, investigated sandstone ser scanner, however, revealed tinct genus and species of bilat- who is now at the Smithsonian cells. The method is also being investigated for its potential ef- to the human brain. However, investigators believe the work deposits in southern Australia. a spindle-shaped organism erian, which they named Ikaria Institution. (Proceedings of fectiveness against coronavirus SARS-CoV-2. provides insight into the inner workings of the mammalian They spotted tiny impressions less than 7 millimeters (mm) wariootia. Based on the rock the National Academy of The interdisciplinary team sought ways to inhibit the action brain. “We still have a lot to learn about the basic principles shaped like grains of rice in a long and 2.4 mm wide that layers in which it was found, the Sciences) —Ashley Braun of hemagglutinin protein found on the surface of influenza vi- of how brains work—things that will hold true no matter what ruses. This spike-like protein binds to sialic acid molecules on Dental Record responded in timing with life the surface of lung cells—the first step in the process that allows The vagus nerve (yellow) events and stressors known to the virus to enter the cell. Previously developed inhibitors latch connects the brain to Unlike the great apes, humans have ex- alter physiological function. onto hemagglutinin, but only weakly. The natural virus muta- the abdomen and to tremely dependent young, and women In teeth from females, the tions that arise in different strains of influenza every flu season other organs. have a long post-reproductive lifespan. researchers found altered can also render these inhibitors ineffective. The evolutionary drivers of this unique cementum bands that cor- To overcome these problems, the Berlin researchers turned lifestyle have been difficult to determine, in responded to reproductive to phage viruses that infect bacterial cells but not human tis- part because researchers had no scientific events. Both male and female sue [see “Viruses: the Ugly, the Bad, and the Good,” by Paul E. processes to investigate life histories in teeth showed cementum Turner, 5/19]. A particularly well-studied example from the hu- the fossilized remains of human ancestors. changes if an individual was man gut, the Q-beta phage, stood out as a promising candidate. Recently, however, researchers developed affected by an illness such as The phage’s capsid—a shell containing genetic material—is a new method for identifying important malaria or HIV. More unex- composed of 180 identical proteins that are ideally spaced apart events, such as childbirth and menopause, pectedly, said Cerrito, stress- to fit the shape of hemagglutinin. “The structure of this capsid by analyzing human teeth. ful events, such as incarcera- is known in exact detail,” says Andreas Herrmann, head of mo- Led by anthropologist Paola Cerrito at tion and relocation, were re- lecular biophysics at Humboldt University of Berlin and one of New York University, a team of scientists corded in the cementum. “We the study’s senior authors. studied forty-seven teeth from fifteen indi- had no idea that there was The team chemically modified the phage shell by studding it viduals with known life histories. They used something in our bodies that with sialic acids. When exposed to influenza in the laboratory, the various microscopic imaging techniques would record these important phage shells latched onto any hemagglutinin spikes with which to examine the dental tissue cementum, physiological events for the they came into contact. This binding vastly reduced flu viruses’ which covers the root of the tooth. Cemen- entirety of our life,” she said. ability to infect lung cells in both animal models and lab-grown tum grows throughout a person’s life and Cerrito noted that the Stressful events

human tissue. Should flu viruses develop resistance and no longer NICOLLE RAGER FULLER/SCIENCE PHOTO LIBRARY accumulates annually in a series of bands, method is limited by a num- form darker lines bind in the same way to sialic acids, according to the researchers, similar to tree rings. The team measured ber of factors. Cementum (running diagonally, the bait molecules on the phage shell can easily be adjusted. animal’s head you found it in,” said Coltan G. Parker, a neuro- the total thickness of the cementum, as well growth rate varies between indicated by arrows) Phages can trigger immune reactions in humans even though science PhD candidate and lead author of the study. as the distance from each detectable band individuals, so the age at along the cementum they are not infectious. However, the phage shells were well- Parker’s colleague Elizabeth A. Davis, now a postdoctoral to the edge of the cementum layer. death (or tooth extraction) (yellow bar across its tolerated by both animal and human models. More studies scholar at the University of Southern California, said the find- The researchers used each individual’s needs to be known. In ad- width) of teeth. will be needed before phage therapy can be developed into a ing could help researchers understand the science underlying age and cementum thickness to calculate dition, researchers cannot PAOLA CERRITO PAOLA potential weapon against influenza—or covid-19. “Eventually, the gut-brain interactions that many people commonly experi- the rate of cementum growth, allowing currently differentiate types if all these studies are promising, biotechnology resources have ence. “Examples include why some people get nauseated when them to determine when each cementum of stressful events without knowledge of nation. “We are pretty confident that each to be developed for large-scale production, and clinical trials they are anxious, [or] why people get ‘hangry’ (angry because band formed. They then examined the an individual’s life history. Cerrito is now stressor is going to alter the metabolism in [in human patients] are mandatory,” Herrmann said. (Nature they are hungry),” she said. (Autonomic Neuroscience: Basic bands for changes in microstructure and working on determining an “elemental fin- its own way.” (Scientific Reports) Nanotechnology) —Adam Hadhazy and Clinical) —Jane C. Hu found that bands with altered structure cor- gerprint” that will allow for such discrimi- —Niki Wilson

6 NATURAL HISTORY June 2020 June 2020 NATURAL HISTORY 7 SAMPLINGS

Rhino Sentinels rorynchus) that ride on rhinos’ backs seem had oxpecker riders. But when Plotz and Critically Endangered black rhinos (Diceros to function as security alarms. Linklater looked for untagged rhinos, trying bicornis) have poor vision, relying more on Oxpeckers, perched on the backs of to approach them without the aid of radio smells and sounds to sense their surround- grazing mammals, pick off parasites, such telemetry, those with oxpeckers were much ings. They are vulnerable as ticks, from their hosts’ skin. But they more difficult to find. By comparing the to poachers, who approach are also parasites, feeding on blood two groups, the authors calculated that the quietly and from downwind. from open wounds. From the Swahili birds helped rhinos avoid human detection However, rhinos may have name for the oxpecker—Askari wa 40 to 50 percent of the time. a defensive ally. Red-billed kifaru, or “rhino’s guard”—environ- The scientists next investigated whether

oxpeckers (Buphagus eryth- JED BIRD mental scientists Roan Plotz, of Victo- rhinos eavesdrop on oxpecker alarm calls. ria University, Melbourne, Austra- They systematically snuck up on eleven lia, and Wayne Linklater, of Cali- tagged rhinos from downwind. In eighty-six fornia State University Sacramento, trials, rhinos without oxpeckers failed 77 suspected the birds provided an percent of the time to notice the approach- additional service that led rhinos to ing researcher. But rhinos with oxpeckers tolerate this practice. that called out in alarm detected the re- The two researchers designed a searchers “every single time,” said Plotz. series of experiments to test whether The more birds a rhino carried, the far- black rhinos in Hluhluwe-iMfolozi ther away it was able to detect an oncoming Park in KwaZulu-Natal, South Af- person. Although the calls did not indicate rica, used oxpecker alarm calls as the direction of the threat, the rhinos al- warnings. Over the course of twenty- most always turned to face downwind. This seven months, they conducted 200 behavior confirmed for the researchers that searches and counted the number of the rhinos do indeed eavesdrop on oxpeck- New research suggests that black oxpeckers found on rhinos. er calls. Reintroducing the birds to areas rhinos listen to the alarm calls of When the scientists sought out where they are now largely absent might be oxpeckers (inset) to warn them when tagged rhinos, which they were a worthwhile rhino conservation tool, the people approach. able to locate and sneak up on us- authors concluded. (Current Biology)

DALE R. MORRIS ing radio telemetry, the majority —Lesley Evans Ogden Early Crop Cultivation phytoliths were identified as belonging to specific plants based on their shape. The researchers found scalloped spheres that formed in Amazonia inside squash rinds, heart-shaped phytoliths from a cassava ances- Hunter-gatherers are thought to have inhabited the Amazon basin tor, and wavy cylinders from corn cobs, suggesting that these crops as early as 10,000 years ago. Now, a study provides the first ar- were once cultivated in the area. chaeological evidence that these people were cultivating crops that The corn cob phytoliths were matched to a variety of corn thought are the ancestors of today’s cassava, squash, and corn, among oth- to have been brought to the Amazon from Mexico, where it was first ers. The findings suggest that the Amazon region domesticated. Lombardo and his col- could be considered one of the major centers of leagues found the pieces they dated early crop cultivation, along with previously known to be about 6,850 years old, sug- areas in China, the Middle East, Mexico, and the gesting that corn’s domestication in Andes. Mexico occurred hundreds of years Umberto Lombardo, an earth scientist at the earlier than previously thought. University of Bern in Switzerland, and colleagues Today, the forest islands are no sampled sediments from eighty-two “forest is- longer inhabited by humans. But lands” in the Bolivian savanna. Forest islands when they were, the region saw sig- are areas where human inhabitants deposited nificant environmental transforma- food waste, shells, and other organic material tions, such as changes in the course for thousands of years. Their refuse created of rivers, according to Lombardo. mounds of rich soil that rise above the surround- Human actions also led to the cre- ing savannah—which is often flooded—and allow ation of habitat for some species, patches of forest to grow. Radiocarbon dating such as the Critically Endangered

of soil from thirty-one forest island sites shows LOMBARDO ET AL. blue-throated macaw (Ara glau- that humans inhabited the area for about 8,000 The shape of tiny mineralized sediments cogularis), which lives only in the years, starting around 10,850 years ago. found in Amazonian forest islands reveals forest islands. Future research The researchers processed the soil samples in the plant species once cultivated there. may further investigate ecosystem order to extract microscopic pieces changes and how human of silica known as phytoliths, inhabitants reacted to them, which form when sediment miner- Lombardo said. (Nature)

alizes inside a plant. Some of these —Kati Moore RUIZ-PÉREZ JAVIER

8 NATURAL HISTORY June 2020