Science News
Headlines
. Antarctica Once Hosted Vast Forests
. Mars has air, but almost none of it can keep you alive
. How the body adapts to extreme heat
. How ‘singing’ mice belt out their tiny tunes
Read more details on some of these topics below.

. Antarctica Once Hosted Vast Forests
A small piece of amber found in West Antarctica is changing how
scientists picture the continent’s past. Found underground in the Pine Island Trough, it shows that resin-producing trees once lived close to the South Pole.

The fragment dates back between 92 and 83 million years ago, during the
mid-Cretaceous. At that time, the Earth was warm, with high sea levels
and many different life forms lived both on land and in the sea. The
amber piece provides a direct link to a time when Antarctica supported forested landscapes very different from today.

The sample, called Pine Island amber, was collected in 2017 during an expedition aboard the RV Polarstern. Scientists used the MARUM-MeBo70 seafloor drill to extract sediment cores from the Amundsen Sea Embayment. And this is the first confirmed amber ever found in Antarctica, which makes the find stand out right away.

The identification of amber in Antarctica fills a long-standing gap in the fossil record. Before this, the southernmost known deposits dated to the mid-Cretaceous in southern Australia and New Zealand.

Amber forms from plant resin, typically found on the barks of
gymnosperms like pine trees and conifers. This indicates
that conifer-dominated forests once thrived in a swampy, temperate rainforest environment near the South Pole. This idea may sound surprising, but it fits with other evidence pointing to a much warmer climate during the mid-Cretaceous, when forests could grow even at high latitudes.

The piece itself contains transparent and translucent particles, which
point to good preservation. This likely means the amber was buried at
shallow depth, avoiding the kind of heat and pressure that would damage
it. Such studies help us to better understand the conditions on Earth at
such early times.

. Mars has air, but almost none of it can keep you alive

A person can step onto the planet with food, water and shelter plans in place, but none of that matters for long without something far more basic: oxygen. On Earth, breathing feels automatic because the atmosphere does the work for you. On Mars, it does not.

That difference starts with the air itself. Here on Earth, oxygen makes up about 21% of the atmosphere. Nitrogen takes up most of the rest, about 78%. When you breathe in, you take in all of it, but your body uses the oxygen and gets rid of the rest when you exhale.

Mars offers a much harsher version of air. Its atmosphere is thin, with only about 1% of the volume of Earth’s atmosphere. Put another way, Mars has 99% less air than Earth. The planet is about half Earth’s size, and its weaker gravity cannot hold atmospheric gases as effectively, allowing them to escape into space.

That alone would make breathing difficult. The composition of the
Martian atmosphere makes it deadly: the planet is
full of the wrong gas!

The most abundant gas on Mars is carbon dioxide. On Earth, carbon dioxide becomes poisonous at high concentrations, though it makes up far less than 1% of the atmosphere. On Mars, it makes up 96% of the air.

Oxygen, by contrast, is almost absent. It accounts for only one-tenth of one percent of the Martian atmosphere, nowhere near enough for a human being to survive. Without a spacesuit supplying oxygen, a person on the surface would die almost immediately. The source material describes two things happening at nearly the same time: suffocation and blood boiling because of the low atmospheric pressure.

It is a brutal reminder that Mars is not just distant. It is actively hostile to human life.

The air is only part of the problem.
Very little liquid water exists on the Martian surface. Temperatures
plunge low, especially at night, when they can fall below minus 73 degrees Celsius. 
That does not mean Mars is beyond scientific hope. So far, researchers have found no evidence of life there. But the search remains in its early stages, and robotic probes have only begun to investigate the planet.

That matters because extreme conditions do not automatically rule out life. On Earth, organisms survive in places that once seemed impossible. Life exists in Antarctic ice, at the bottom of the ocean and miles beneath Earth’s surface. Many of those environments bring severe cold or heat, almost no water, and little to no oxygen.

There is also the deeper possibility that Mars was once very different. The source material notes that billions of years ago, the planet may have had a thicker atmosphere, more oxygen, warmer temperatures and significant amounts of liquid water on its surface. If that was the case, Mars may once have been much more favorable to life than it is today.

That idea sits at the heart of NASA’s Perseverance mission which is a
robotic explorer right now on the surface of Mars.
One goal of the Perseverance rover is to search for signs of ancient
Martian life--most likely microbes, preserved in rock.

At the same time, Perseverance is doing something else that could shape Mars exploration in a more immediate way.
Among the rover’s seven instruments is MOXIE, a device designed to take carbon dioxide from the Martian atmosphere and convert it into oxygen. On a planet where carbon dioxide dominates the air, that is a striking idea: use the planet’s most abundant gas to help solve one of its most dangerous problems.

If MOXIE works the way scientists hope, the benefits would go beyond breathing. Future astronauts could make their own oxygen on Mars instead of carrying all of it from Earth.

That changes the equation. The more oxygen astronauts can produce on Mars, the less they need to launch from Earth. And the less mass a mission has to carry across space, the easier it becomes to send people there.

Still, even “homegrown” oxygen would not make Mars comfortable. Astronauts would still need spacesuits. The planet’s thin atmosphere, low pressure, cold temperatures and lack of breathable air would not disappear just because some oxygen could be manufactured on site.

NASA is now working on the technologies needed for human missions to Mars. Such a mission could happen in the next decade, perhaps sometime in the late 2030s.

. How the body adapts to extreme heat

“I can’t do this,” the woman in her 60s said as she lowered herself into
the 40° Celsius water that filled a big silver tub at the end of a dimly
lit room in the University of Ottawa’s Human and Environmental
Physiology Research Unit. It was only after the temperature dropped a
degree that she immersed herself, shoulder-deep, for the next two hours.
Then she did it again — and again and again — every day for a week. This
was part of an experiment to study how the human body adapts to extreme
heat. In particlar, to study if older women---in their 60s, 70s and
80s---could train themselves to cope better with hotter temperatures. In
this day of climate change and global warming, elderly people are
particularly at risk of dying due to excess heat. One way of protecting
such people is to get them accustomed to warmer temperatures. Hence this
unusual experiment!

Extreme heat can kill. When a person’s core body temperature rises above
the normal 37° for long periods, heat exhaustion often sets in. Hotter
temperatures can eventually lead to delirium, seizures, organ failure
and death.

As heat wave–related deaths mount globally — more than 10,000 Europeans are estimated to have died during a heat wave in June alone — harnessing the body’s natural responses could be one way to survive in an increasingly hot world.

Repeated exposure to high temperatures in young, healthy individuals has been shown to trigger protective physical changes that help cool the body.
Studies in athletes, soldiers and outdoor workers, have shown that
repeated exposures to heat trigger certain physiological responses.
These help the body to better cope with subsequent bouts of heat.

For example, sweating, which uses moisture to take away heat, starts
earlier and is more intense in people who have recently been exposed to
hot temperatures. Tiny blood vessels in the skin also dilate more
quickly in heat-exposed individuals. This allows more blood to move from
the body’s hotter interior to its surface, where heat can radiate outward. These changes initially force the heart to beat faster to keep blood pressure steady. Over time, the body adapts by expanding blood volume, reducing the heart rate.

Studies have found that the hypothalamus, a brain region that acts like
a thermostat, becomes more sensitive to temperature and acts more
quickly to trigger sweating and blood-vessel widening. In addition,
cells in the blood (and probably elsewhere in the body) produce more heat shock proteins, which help protect cells from heat-related damage.

While researchers are still figuring out precisely how these
physiological adaptations work, some scientists believe they are at
least partly the reason why people in climates that are hot year-round tend to suffer less from heat.

Residents of countries including Kuwait, India and Thailand, for example, show signs of being well-adapted to relatively high average daily temperatures.

To compare the heat tolerance of people from different places,
scientists calculated the minimum mortality temperature (temperature at
which there is danger of heat death) for two groups. One group were the
residents of Mecca, Saudi Arabia. The other group were the international
visitors who visit Mecca for Hajj. They looked at patterns of natural
deaths for both populations during the five-day Hajj period over eight
years from 2006 to 2014. They found a minimum mortality temperature of
26° for Meccans and 23.5° for pilgrims. This is the minimum temperature;
they found that, above 38°, mortality for Meccans shot up drastically.

In general, such differences at the population level could be due to
many factors, including access to air conditioning, outdoor conditions
and possibly even genetic factors. But physiological acclimation
probably also plays a role.

What about the original experiment of immersing yourself in hot water
that we begn this report with? 
After repeatedly immersing themselves for seven days, both older adults
and younger adults started to sweat and vasodilate earlier upon heat exposure. They also experienced a 0.4° lower body temperature, on average, than they did at the beginning of the experiment. The scientists also observed a five-beats-per-minute lower heart rate, on average, in both groups by the end of the protocol, they reported in May in the Journal of Physiology.

The upshot of the study “is that even if we’re older, our body still has the ability to adapt to heat.”

. How ‘singing’ mice belt out their tiny tunes

Disney’s Cinderella is not the only place you can hear mice “sing.” Some real-world rodents also serenade each other.
They are known as Alston’s singing mice. Found in the forests of Mexico and Central America, they truly live up to their name. Both males and females communicate with trains of high-pitched notes. Remarkably, their songs are more complex than those of any other rodent. Making music this way may be unique in the animal kingdom.

In just a 10-second song, an Alston’s singing mouse belts out around 100
individual breaths and notes. The melody attracts mates and warns rival
males to stay away, says Samantha Smith of the University of Lausanne,
Switzerland. The song’s speed and length make it far more “extreme” than other rodents’ calls, she adds.

Smith is part of a team that wanted to know how the vocal systems of
Alston’s singing mice evolved to create melodies. They started by
dissecting the voice boxes of deceased animals. This “voice box” is a part of their bodies that helps mice (and us) breathe, swallow and make sound.

The researchers hooked each voice box to a tube. Then, they pointed a microphone and camera toward its top. “A voice box is basically just a tube with a valve in it that can open and close,” explains Smith. To see how the voice box moved and produced sound, the team blew air through the tube.

Sometimes, the voice box produced sounds that ranged in the mouse’s natural pitch. But this happened only when a pouch on the inside of the voice box was inflated. When the researchers blocked this balloon with bits of wax or small metal balls, the voice box went silent. Cutting the sac had the same effect. The air sac, it seemed, is key to making the songs.

Other rodents have air sacs, but they don’t appear to use them to sing.

Working with voice boxes this small is not an easy task. But learning
more about how rodents produce sound is exciting because they’re such a diverse group with such fascinating social, behavioral and ecological adaptions.

It’s not yet clear how the sac generates its whistle. The sound could come from air vibrating at the sac’s entrance.
Another possibility is a bit like how flutes and organ pipes work. A sharp cartilage rim at the sac’s entrance may be deflecting air, producing the tone.

Inflatable sacs in airways have evolved multiple times. Primates, birds, reptiles, frogs and other animals have them. But in those cases, air sacs alter or amplify sound produced elsewhere in the respiratory tract. (That’s the system of organs that are involved in breathing.) The songs of the singing mice, on the other hand, are made by the sacs themselves.

“Our study expands our understanding of the ways in which [air sacs] can
shape vocal communication,” Smith says. Studying different features of
rodent air sacs may help reveal how these songs first evolved.

Source: www.dailygalaxy.com; 
https://www.thebrighterside.news;
www.sciencenews.org;
https://www.snexplores.org