Science
Bees learn waggle dance moves with a little help from their coworkers
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Booty-shaking worker bees guide their fellow workers to pollen by a form of communication known as “waggle dancing” — performing steps that map out where food is located and how far it is from the hive.
And now scientists have discovered that bees hone these moves when they’re young, by touching their antennae to the bodies of dancing elder bees; if they miss that chance, their dances have more mistakes, and their maps are less accurate.
Waggle dances are tricky to execute, and missteps can send foraging bees flying off in the wrong direction. But there’s a critical learning phase in a young worker bee’s life when she’s about eight days old — right before she becomes a full-fledged forager — which helps her to perfect her dance.
When older workers return to the hive and waggle dance, novice workers observe them closely. By doing so, less-experienced bees learn to perform dances that generate more accurate maps to the next meal. Worker bees are all female.
Genetics play a part in bees’ dances, and earlier studies have shown that some dance details relaying distance are species-specific.
However, the new findings demonstrate that the language of bees’ dances is not entirely innate but is partly shaped by social learning, scientists reported Thursday in the journal Science.
They also found that if newbie workers were deprived of the chance to learn from more experienced bees, they produced dances that were sloppier, with more errors. Some aspects of their map-dancing improved with time, but other nuances were lost for good.
Waggle dance communication is complex, and the bees’ task is further complicated by having to perform on vertical, irregular honeycomb stages with no light, said study coauthor James Nieh, a professor of biology at the University of California, San Diego.
“As a waggle dancer, you’re running forward, rushing at about one body length per second over this open dance floor that has holes in it,” Nieh said.
“You’re surrounded by hundreds and thousands of bees that you have to push out of the way, and it’s in complete darkness.” Bees in the colony follow the dance through physical contact with the dancer, he added.
Despite the challenges, a bee has to use her body to convey lots of information subtly. A dancer follows a straight line, called a “waggle run,” then loops back to the starting point in alternating left and right curves; she does this repeatedly, making a figure-eight shape. Duration of the waggle run tells her hive mates how far away the food is, and the waggle run’s angle relative to the central line points the direction to the food source.
What would happen if young bees didn’t have the chance to watch others dance? To find out, the researchers created five colonies where all the bees were the same age, with no experienced elders. When the bees were old enough to forage, the study authors recorded their dances and then compared them with dances of bees in five control colonies containing adults of different ages.
“They could all dance,” Nieh said. “But bees that could follow more experienced dancers — the teachers — danced a lot better.”
In their earliest dances, the bees that had no guidance performed dances with more mistakes in their direction angles and in the distance encoding communicated by the vertical waggle run.
By the time the bees were 20 days old and fully mature, experienced foragers, their performances had improved — up to a point. Their dances were more orderly, with fewer directional errors. “However, they could never correctly communicate distance,” Nieh said. Once those mistakes were encoded in the dance, the teacherless bees repeated the errors for the rest of their lives.
“What amazed me most is that this represents a new level of complexity in the transmission of information within a bee colony,” bee researcher Paul Siefert, who was not involved in the study, told CNN in an email.
“While we previously thought that the waggle dance was at best defined by genetics and mechanical capabilities, we now know that there is a social component to learning the dance,” said Siefert, a research associate at the Institut für Bienenkunde Oberursel of the Polytechnische Gesellschaft, Goethe University Frankfurt in Germany.
The findings also raise questions about the role that social learning may play in other interactions within a honeybee colony, “for instance, in hygienic behavior against Varroa mites,” a parasite that targets honeybees, Siefert added.
Another question that scientists are hoping to answer is if social learning could shape changes in a colony’s waggle dance, so that updates about shifts in their ecosystem could then be relayed to younger bees through their elders’ waggles, Nieh said.
“We would see how rapidly they could adapt to that local circumstance and pass that information on, really testing this hypothesis that distance encoding reflects the habitat.”
Tonight, just after sunset, skywatchers across B.C. will be in for an eye-popping show.
Five planets — Mars, Uranus, Venus, Mercury and Jupiter — will be lined up in an arc and visible on the western horizon from almost anywhere on Earth.
“I like to call it, essentially, a cosmic coincidence,” said Andrew Ferreira, a public relations representative with the Vancouver branch of the Royal Astronomical Society of Canada.
“It’s purely just a coincidence that, you know, five planets happened to line up more or less from our perspective.”
In an interview with CBC, Ferreira said the best time to view the phenomenon will be just after the sun drops below the horizon. Keeping watch just after sunset is best, because as the night sky moves, “it’s essentially going to keep panning these planets down below the horizon.”
Ferreira’s suggestion is to spot the half-moon in the sky and trace a visual line down from there to see Mars. Below that will be Uranus and Venus. Below Venus will be Mercury, and closest to the horizon will be Jupiter.
Ferreira said Venus will outshine Uranus, but Uranus will be visible as a “greenish-blueish glow.” Mercury, he said, will be very faint but visible through binoculars, and people in downtown Vancouver or other urban centres might not be able to see Jupiter because of its low position on the horizon.
Getting away from city lights and buildings increases the chances for clearer viewing. Ferreira said giving your eyes a few minutes to adjust to the sky is also a good idea.
Great conditions for viewing
Of course, people hoping to catch the planetary procession will also benefit from clear skies overhead. And there’s good news on that front.
“The forecast for almost the entire province is looking great for a night-sky viewing,” said CBC meteorologist Johanna Wagstaffe.
“We have a high pressure system in place for B.C. which is bringing cloudless skies for almost everyone. The exceptions are a few high clouds that may sneak in tonight to northern B.C.”
“It may get a little chilly though with no clouds to keep the daytime heat in, so bundle up when you look up tonight.”
Alignments happen once or twice each year
As for the rarity of planetary alignments, Ferreira said ones like tonight happen once or twice each year. But an alignment of all the planets in the solar system, minus Earth, “that’s something like once every 200 or 300 years,” he said. “So it kind of depends on the objects and how many of them are lined up.”
Rare or not, Ferreira said events like tonight are always a joy, even for avid skywatchers like himself.
“It’s exciting being able to tell people about it — to get other people excited about what we do,” he said.
“I always tell people that astronomy is the easiest science to do because all you need is your eyes and the ground. You lie on your back and you look up and you know you’re doing astronomy.”
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An international team of researchers has used the NASA/ESA/CSA James Webb Space Telescope to measure the temperature of the rocky exoplanet TRAPPIST-1 b. The measurement is based on the planet’s thermal emission: heat energy given off in the form of infrared light detected by Webb’s Mid-Infrared Instrument (MIRI). The result indicates that the planet’s dayside has a temperature of about 500 kelvins (roughly 230°C), and suggests that it has no significant atmosphere. This is the first detection of any form of light emitted by an exoplanet as small and as cool as the rocky planets in our own solar system. The result marks an important step in determining whether planets orbiting small active stars like TRAPPIST-1 can sustain atmospheres needed to support life. It also bodes well for Webb’s ability to characterise temperate, Earth-sized exoplanets using MIRI.
“These observations really take advantage of Webb’s mid-infrared capability,” said Thomas Greene, an astrophysicist at NASA’s Ames Research Center and lead author on the study published today in the journal Nature. “No previous telescopes have had the sensitivity to measure such dim mid-infrared light.”
Rocky planets orbiting ultra cool red dwarfs
In early 2017, astronomers reported the discovery of seven rocky planets orbiting an ultracool red dwarf star (or M dwarf) 40 light-years from Earth. What is remarkable about the planets is their similarity in size and mass to the inner, rocky planets of our own solar system. Although they all orbit much closer to their star than any of our planets orbit the Sun – all could fit comfortably within the orbit of Mercury – they receive comparable amounts of energy from their tiny star.
TRAPPIST-1 b, the innermost planet, has an orbital distance about one hundredth that of Earth’s and receives about four times the amount of energy that Earth gets from the Sun. Although it is not within the system’s habitable zone, observations of the planet can provide important information about its sibling planets, as well as those of other M-dwarf systems.
“There are ten times as many of these stars in the Milky Way as there are stars like the Sun, and they are twice as likely to have rocky planets as stars like the Sun,” explained Greene. “But they are also very active – they are very bright when they’re young and they give off flares and X-rays that can wipe out an atmosphere.”
Co-author Elsa Ducrot from CEA in France, who was on the team that conducted the initial studies of the TRAPPIST-1 system, added, “It’s easier to characterise terrestrial planets around smaller, cooler stars. If we want to understand habitability around M stars, the TRAPPIST-1 system is a great laboratory. These are the best targets we have for looking at the atmospheres of rocky planets.”
Detecting an atmosphere (or not)
Previous observations of TRAPPIST-1 b with the NASA/ESA Hubble Space Telescope, as well as NASA’s Spitzer Space Telescope, found no evidence for a puffy atmosphere, but were not able to rule out a dense one.
One way to reduce the uncertainty is to measure the planet’s temperature. “This planet is tidally locked, with one side facing the star at all times and the other in permanent darkness,” said Pierre-Olivier Lagage from CEA, a co-author on the paper. “If it has an atmosphere to circulate and redistribute the heat, the dayside will be cooler than if there is no atmosphere.”
Astronomers can subtract the brightness of the star from the combined brightness of the star and planet to calculate how much infrared light is coming from the planet’s dayside. This is then used to calculate the dayside temperature.
The graph shows combined data from five separate observations made using MIRI’s F1500W filter, which only allows light with wavelengths ranging from 13.5-16.6 microns to pass through to the detectors. The blue squares are individual brightness measurements. The red circles show measurements that are “binned,” or averaged to make it easier to see the change over time. The decrease in brightness during the secondary eclipse is less than 0.1%. MIRI was able to detect changes as small as 0.027% (or 1 part in 3700).
This is the first thermal emission observation of TRAPPIST-1 b, or any planet as small as Earth and as cool as the rocky planets in the Solar System.
The observations are being repeated using a 12.8-micron filter in order to confirm the results and narrow down the interpretations.
MIRI was developed as a partnership between Europe and the USA: the main partners are ESA, a consortium of nationally funded European institutes, the Jet Propulsion Laboratory (JPL) and the University of Arizona. The instrument was nationally funded by the European Consortium under the auspices of the European Space Agency.
[Image description: At the top of the infographic is a diagram showing a planet moving behind its star (a secondary eclipse). Below the diagram is a graph showing the change in brightness of 15-micron light emitted by the star-planet system over the course of 3.5 hours. The infographic shows that the brightness of the system decreases markedly as the planet moves behind the star.]
Credit:
NASA, ESA, CSA, J. Olmsted (STScI), T. P. Greene (NASA Ames), T. Bell (BAERI), E. Ducrot (CEA), P. Lagage (CEA)
The team used a technique called secondary eclipse photometry, in which MIRI measured the change in brightness from the system as the planet moved behind the star. Although TRAPPIST-1 b is not hot enough to give off its own visible light, it does have an infrared glow. By subtracting the brightness of the star on its own (during the secondary eclipse) from the brightness of the star and planet combined, they were able to successfully calculate how much infrared light is being given off by the planet.
Measuring minuscule changes in brightness
Webb’s detection of a secondary eclipse is itself a major milestone. With the star more than 1,000 times brighter than the planet, the change in brightness is less than 0.1%.
“There was also some fear that we’d miss the eclipse. The planets all tug on each other, so the orbits are not perfect,” said Taylor Bell, the post-doctoral researcher at the Bay Area Environmental Research Institute who analysed the data. “But it was just amazing: The time of the eclipse that we saw in the data matched the predicted time within a couple of minutes.”
Analysis of data from five separate secondary eclipse observations indicates that TRAPPIST-1 b has a dayside temperature of about 500 kelvins, or roughly 230°C. The team thinks the most likely interpretation is that the planet does not have an atmosphere.
If the heat energy from the star were distributed evenly around the planet (for example, by a circulating carbon dioxide-free atmosphere), the temperature at 15 microns would be 400 K (125°C). If the atmosphere had a substantial amount of carbon dioxide, it would emit even less 15-micron light and would appear to be even cooler.
Although TRAPPIST-1 b is hot by Earth standards, it is cooler than the dayside of Mercury, which consists of bare rock and no significant atmosphere. Mercury receives about 1.6 times more energy from the Sun than TRAPPIST-1 b does from its star.
MIRI was developed as a partnership between Europe and the USA: the main partners are ESA, a consortium of nationally funded European institutes, the Jet Propulsion Laboratory (JPL) and the University of Arizona. The instrument was nationally funded by the European Consortium under the auspices of the European Space Agency.
[Image description: Infographic titled, “Rocky Exoplanet TRAPPIST-1 b Dayside Temperature Comparison, MIRI F1500W” showing five planets plotted along a horizontal temperature scale: Earth, TRAPPIST-1 b, Mercury, and two different models of TRAPPIST-1 b.]
Credit:
NASA, ESA, CSA, J. Olmsted (STScI), T. P. Greene (NASA Ames), T. Bell (BAERI), E. Ducrot (CEA), P. Lagage (CEA)
“We compared the results to computer models showing what the temperature should be in different scenarios,” explained Ducrot. “The results are almost perfectly consistent with a blackbody made of bare rock and no atmosphere to circulate the heat. We also didn’t see any signs of light being absorbed by carbon dioxide, which would be apparent in these measurements.”
This research was conducted as part of Guaranteed Time Observation (GTO) program 1177, which is one of eight approved GTO and General Observer (GO) programs designed to help fully characterise the TRAPPIST-1 system. Additional secondary eclipse observations of TRAPPIST-1 b are currently in progress, and now that they know how good the data can be, the team hopes to eventually capture a full phase curve showing the change in brightness over the entire orbit. This will allow them to see how the temperature changes from the day to the nightside and confirm if the planet has an atmosphere or not.
“There was one target that I dreamed of having,” said Lagage, who worked on the development of the MIRI instrument for more than two decades. “And it was this one. This is the first time we can detect the emission from a rocky, temperate planet. It’s a really important step in the story of discovering exoplanets.”
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MOSCOW –
A Russian space capsule safely returned to Earth without a crew Tuesday, months after it suffered a coolant leak in orbit.
The Soyuz MS-22 leaked coolant in December while attached to the International Space Station. Russian space officials blamed the leak on a tiny meteoroid that punctured the craft’s external radiator. They launched an empty replacement capsule last month to serve as a lifeboat for the crew.
The damaged capsule safely landed Tuesday under a striped parachute in the steppes of Kazakhstan, touching down as scheduled at 5:45 p.m. (7:45 a.m. EDT) 147 kilometres (91 miles) southeast of Zhezkazgan under clear blue skies.
Space officials determined it would be too risky to bring NASA’s Frank Rubio and Russia’s Sergey Prokopyev and Dmitri Petelin back in the Soyuz in March as originally planned, as cabin temperatures would spike with no coolant, potentially damaging computers and other equipment, and exposing the suited-up crew to excessive heat.
The three launched in September for what should have been a six-month mission on the International Space Station. They now are scheduled to return to Earth in September in a new Soyuz that arrived at the space outpost last month with no one on board, meaning the trio will spend a year in orbit.
Also on the station are NASA astronauts Stephen Bowen and Woody Hoburg, the United Arab Emirates’ Sultan Alneyadi, and Russia’s Andrey Fedyaev.
A similar coolant leak was spotted in February on the Russian Progress MS-21 cargo ship docked at the space outpost, raising suspicions of a manufacturing flaw. Russian state space corporation Roscosmos ruled out any defects after a check and concluded that both incidents resulted from hits by meteoroids.
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