On average, women live longer than men: About 90% of people reaching 110 years old or more are women. The current record holder is Jeanne Calment, who was 122 years old, when she died in 1997.
Now a new study shows, that even greater differences in lifespan are found in wild mammals. The average female wild mammal lives 18.6 % longer than her male counterpart. In humans the difference is “only” 7.8 %.
The study was conducted by researchers from University of Southern Denmark and University Lyon 1 in collaboration with several international teams. It is published in the Proceedings of the National Academy of Sciences of the United States (PNAS).
Moose, killer whale and sheep
– The greatest differences are found in animals like Common brushtail possum, lion, killer whale, moose, greater kudu and sheep, says Fernando Colchero, associate professor and an expert in biostatistics at Interdisciplinary Centre on Population Dynamics, University of Southern Denmark.
The researchers compiled demographic data for more than 130 wild mammal populations and were able to estimate the average longevity and the rate of increase in the risk of dying as a function of age for both sexes.
The analyzes led to unexpected results. Not only do females generally live longer than males in wild mammals, but the difference in longevity between the sexes, although very variable depending on the population, in the vast majority of cases exceeds the difference observed in human populations.
Lower risk of female mortality during adulthood
– For about half of the mammal populations studied, the increased risk of mortality with age is actually more pronounced in females than in males, Fernando Colchero explains.
These results show that the larger longevity of females than males is most likely due to other factors that affect individuals during their entire adult life.
To reach this conclusion, Colchero and his colleagues calculated the average age at death, as well as the rate at which mortality increases with age.
Is risky male behavior a cause?
There is a common belief that males engage in potentially dangerous sexual competitions and live riskier lives than females, and that this could account for their shorter lifespan.
Contrary to this idea, this study reveals that the intensity of sexual selection does not directly modulate the amplitude of the differences in longevity observed between the sexes.
The results rather suggest that complex interactions between the physiological characteristics specific to each sex and local environmental conditions are at play.
We see many variations in the species studied. For some species, the males actually have the longest lifespan. That said, there is a statistically clear trend and there are a number of plausible explanations, says Dalia Conde, associate professor and an expert in animal conservation, Department of Biology, University of Southern Denmark.
Why do the females live longer?
One explanation is that males often are larger and put more energy in sexual characters such as growing larger horns than females. This requires energy, and if the animals live in a harsh climate, the males may be more vulnerable to these extreme environmental conditions.
One example is bighorn sheep (Ovis canadensis), When these animals live in an environment where resources are consistently available, there are almost no differences in their lifespans. But when they live in harsher environments, where winters are more severe, the males live much shorter lives.
Another explanation is that males produce more androgens (male hormones) than females. Androgens modulate immune performance and when present at high levels, they can impair some aspects of the immune defense, making males more susceptible to infections and diseases.
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
Mercury-bound spacecraft buzzes Earth, beams back pictures – CityNews Edmonton
CAPE CANAVERAL, Fla. — A Mercury-bound spacecraft swooped past Earth on Friday, tweaking its round-about path to the solar system’s smallest and innermost planet.
Launched 1 1/2 years ago, Europe and Japan’s Bepi-Colombo spacecraft passed within 8,000 miles (12,700 kilometres) of Earth. The closest approach occurred over the South Atlantic, with telescopes in Chile catching a glimpse of the speeding spacecraft.
The gravity tug from Earth slowed Bepi-Colombo and put it on a course closer to the sun.
It was the first of nine planetary gravity assists — and the only one involving Earth — on the spacecraft’s seven-year journey to Mercury. The spacecraft — comprised of two scientific orbiters — should reach Mercury in 2025, after swinging twice past Venus and six times past Mercury itself. The next flyby will be at Venus in October.
Before leaving Earth’s vicinity, Bepi-Colombo beamed back black-and-white pictures of the home planet. The spacecraft holds three GoPro-type cameras.
“These selfies from space are humbling, showing our planet, the common home that we share, in one of the most troubling and uncertain periods many of us have gone through,” Gunther Hasinger, the European Space Agency’s science director, said via Twitter.
The space agency’s control centre in Germany had fewer staff than usual for Friday’s operation because of the coronavirus pandemic. The ground controllers sat far apart as they monitored the flyby. Data from the flyby will be used to calibrate Bepi-Colombo’s science instruments.
Scientists hope to learn more about the origin and composition of Mercury, once the European and Japanese orbiters separate and begin their own circling of the scorched planet.
Mercury is the least explored of our solar system’s four rocky planets. It’s just a little bigger than our moon and circles the sun in just 88 days.
The spacecraft is named after Italian mathematician and engineer Giuseppe “Bepi” Colombo, who devised the use of planetary flybys for Mercury encounters. He died in 1984.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
Marcia Dunn, The Associated Press
50 years after Apollo 13, we can now see the moon as the astronauts did – Space.com
This Saturday (April 11) will mark 50 years since NASA’s Apollo 13 mission launched on an unexpectedly tumultuous journey around the moon. Now, a modern lunar orbiter has reconstructed what the Apollo 13 astronauts would have seen of the lunar surface.
Famously described as a “successful failure,” Apollo 13 did not go as planned: An oxygen tank exploded 56 hours into the mission. Thankfully, some fast-thinking teamwork between the astronauts and mission control back on Earth salvaged the mission and, after a trip around the moon, the astronauts safely returned to Earth.
So, while the crew didn’t land on the moon as planned, they did travel around it and, thanks to modern technology, we can now see what they saw on this journey.
A photo of the lunar surface taken by the Apollo 13 astronauts on their trip around the moon.
Soon after sunrise, the Apollo 13 crew snapped this incredible shot of the moon.
A snapshot of the Tsiolkovskiy crater, taken by the Apollo 13 crew with a telephoto lens.
Researchers used data from NASA’s Lunar Reconnaissance Orbiter mission to recreate what the Apollo 13 crew saw as they flew around the far side of the moon. In the video, you can see craters and other lunar features emerge from the darkness. You can imagine yourself as any of the crewmembers — commander Jim Lovell, command module pilot Jack Swigert or lunar module pilot Fred Haise — looking down and watching the lunar surface pass by as the spacecraft flew overhead.
In addition to the Lunar Reconnaissance Orbiter data, the researchers also consulted the Apollo 13 flight plan and, despite the major change in plans with the mission, were able to use the position and speed at the craft’s closest point to the Moon which was listed in the Apollo 13 Mission Report. Taken together, those details allowed them to determine factors including the position and speed of the spacecraft at its closest point to the moon, which helped clarify the vehicle’s trajectory.
To create this virtual trip around the moon, this team was also informed by photos taken by the Apollo 13 crew during this trip around the moon. You can see some of the captivating original images above, but you can also find every Apollo 13 photo ever online in the Apollo Image Atlas.
Shine on, shine on – Skywatching – Castanet.net
The moon is unusual. There are bigger moons in the Solar System, some with under-ice oceans and at least one with a thick atmosphere.
However, all those other moons orbit giant planets.
Our moon is so large compared with the Earth that sometimes the pair get described as a double planet.
This suggests that something happened that differs from what went on in the young Solar System, when the planets formed.
The standard picture is the collapse of a cloud of gas and dust into a rotating disc. The core forms a star, the Sun, the disc forms smaller discs that collapse into planets, and the left over material forms moons, all far smaller than the planet.
There is a limit to how small one of these collapsing discs can be because the body in the centre has to have enough gravity to hold it together, and with lots of bodies forming nearby, all their conflicting gravitational attractions cause small discs to dissipate.
The moon is too big to be a by-product of the Earth’s disc and too small to have a disc of its own. So, where did it come from?
One suggestion was that the young Earth was spinning too quickly to hold itself together and spun off the moon.
The theory that seems to best fit the bill as we see things at present is that soon after the Earth formed it was hit by an object around the size of Mars. The resulting chaotic debris then collapsed to form the Earth and moon.
The “pre-Earth” was a fully formed planet when it was hit. Heavy elements such as iron and nickel had settled down into the centre, forming the core, and the material surrounding it, volcanic rocks such as basalt formed a mantle.
This stuff was semi-molten, as it is today, with a cooler, solidifying surface of basalt rocks, rather like the floor of our oceans today. The impact was unlikely to have been dead centre, because the debris cloud would have been thrown off so fast it would never fall back to form only one or two bodies.
An off-centre impact would have removed a large lump of the pre-Earth’s mantle and a bit of core. This agrees with the geological information and the rock samples brought back from the moon by the Apollo astronauts.
The moon ‘s rocks are very much like the basaltic rocks making up the Earth’s ocean floor and mantle. The main difference is that the rocks the astronauts managed to grab were from the moon ‘s surface, and have been exposed to billions of years of vacuum and hot and cold, and as a result are extremely dry.
After things settled down again, we had a young Earth that rotated faster than it does today, and the moon orbited much closer. The two worlds pulled up huge tides in each other, and the rapid rotation of the Earth pulled the tidal bulge a bit ahead of the moon.
The gravitational pull of the bulge pulled at the Moon, speeding it up, and perversely, the way orbits work is that trying to speed an object up makes its orbit move further away and makes it move slower.
Try swinging a ball around your head on the end of a couple of metres of elastic. Once you have it moving in a nice circle, try to speed it up. It will move away and slow down. This is definitely a “do outdoors and use eye protection experiment.” Believe me, I’ve done it.
While the pull of the tidal bulge accelerated the moon, it slowed the Earth’s rotation, so that today our day is 24 hours long. This tidal process has not finished.
The moon is still receding from us, and our days are still lengthening.
One consequence of this is that one day there will no longer be any total eclipses of the Sun.
That our moon is at the right distance from us to exactly cover the Sun is probably unique in our galaxy, and this lucky coincidence won’t last forever.
- Venus shines brightly in the west after sunset
- Left to right, Mars, Saturn and Jupiter lie close together low in the southeast before dawn
- The moon will reach Last Quarter on the 14th.
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