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Grandmas may be key to species survival, says new study

New research on killer whales may shine a light on the evolutionary power of menopause.

Grandmas may be key to species survival, says new study
Photo Credit: Dan Antoche-Albisor / Getty Images
  • New research on killer whales suggests that post-menopausal grandmothers play a powerful role in the survival of generations that follow them.
  • "The Grandmother Hypothesis," theorizes that by surviving long past menopause, a woman improves the survival and reproduction of her children's children and, thus, her own genes.
  • Not only do grandma whales help raise and share their own food with their grandoffspring, they bequeath decades of foraging wisdom onto the next generation, guiding them to the best feeding spots.

The phenomena of menopause is a conundrum that has long baffled evolutionary biologists. But new research on killer whales suggests that this is because grandmothers play a powerful role in the survival of subsequent generations.

The Grandmother Hypothesis

Around age 50, a woman's ovaries stop producing eggs, officially liberating her from her reproductive responsibilities and biological functions: Menstruation, pregnancy, lactation, repeat. Though many primates die out after this point, humans live on decades after menopause. From an evolutionary perspective, this suggests that women are essential to the survival of our species beyond their direct ability to bear children.

Enter "The Grandmother Hypothesis," which has theorized that by surviving long past menopause, a woman improves the survival and reproduction of her children's children. This way, she ensures the continuation of her own genes into the next generation. In the past, skeptics dismissed the hypothesis, arguing it's always more genetically beneficial for a female to have her own children, rather than throwing in the towel half-way through and using her time and energy to help raise her children's children.

But a new paper published in PNAS last month tested and significantly backed the powerful benefits of having post-reproductive grandmothers in killer whales communities.

New research on “postmenopausal” whales

Credit: CC0 Public Domain

Like humans, female whales live decades past their reproductive potential. And, like humans, they can continue to have babies after they become grandmothers. In a new study, researchers sought to find out if post-reproductive grandmother whales helped their offspring better than grandmothers that were still reproducing. Of course, to get the genetic "fitness" benefits, grandmothers and their offspring need to be able to interact. In killer whale communities, offspring do not leave their mothers once they reach reproductive age. This results in a close-knit matrilineal family structure in which a grandma whale groups with her offspring.

To do the test, the researchers collected data on two groups of killer whales. One group in the coastal waters of Washington State and the other in British Columbia, Canada. Genealogical whale relationships were inferred from long-term observations of social organization, and mothers were identified by their repeated association with young calves. The researchers recorded whale births and deaths, and also controlled for the important environmental factor of salmon abundance.

What the researchers discovered was that not only did grandmothers significantly increase the survival of their grandoffspring, but grandmothers were even more beneficial to their grandcalves when they were no longer reproducing.

Why grandmother whales are vital resources

The study found that if a whale lost its grandmother, its survival rate took a sharp dip within the two years of her death. This was true even of whales who were up to 20 years old. When salmon abundance was lower, the role of the grandmother whale was found to be more significant, suggesting that the grandma whale's accumulation of ecological knowledge was a vital resource for the survival of whale families.

After all, whales are gregarious creatures. Young killer whales need guidance in finding food after they have been weaned. Not only do grandma whales help raise and share their own food with their grandoffspring, they bequeath decades of foraging wisdom onto the next generation, guiding them to the best feeding spots. The researchers noted that as salmon populations continue to decline due to ecological threats, whale grandmothers may become increasingly important.

This beneficial effect was enhanced when the grandmother whale was no longer reproducing. It makes sense, as she wouldn't be using her time, energy, and resources being pregnant, lactating, or ensuring her new children survives. This corroborates previous studies that found that menopause might be beneficial because it means that competition for resources is thinned out between generations of females. This could be why in humans, women on average tend to stop reproducing almost right around the time when their offspring start.

The power of grandmas

Grandmother's birthday, by Arturo Ricci

Credit: Wikimedia Commons

The authors claim that their findings help explain why killer whales have evolved the longest post-reproductive life span of all nonhuman animals: Natural selection has decided that post-reproductive grandmas are extremely valuable resources. Perhaps this is why humans have a longer post-reproductive life span than other primates. The study offers an enchanting example of nature's symmetry, and proves the value of all phases of feminine family roles in the evolution and continuation of the human race.

Ultimately, this study proves what many of us intuitively knew: Grandma is a badass. It's grandmothers, and the generations of matriarchs before them, we can thank for our existence.

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Quantum particles timed as they tunnel through a solid

A clever new study definitively measures how long it takes for quantum particles to pass through a barrier.

Image source: carlos castilla/Shutterstock
  • Quantum particles can tunnel through seemingly impassable barriers, popping up on the other side.
  • Quantum tunneling is not a new discovery, but there's a lot that's unknown about it.
  • By super-cooling rubidium particles, researchers use their spinning as a magnetic timer.

When it comes to weird behavior, there's nothing quite like the quantum world. On top of that world-class head scratcher entanglement, there's also quantum tunneling — the mysterious process in which particles somehow find their way through what should be impenetrable barriers.

Exactly why or even how quantum tunneling happens is unknown: Do particles just pop over to the other side instantaneously in the same way entangled particles interact? Or do they progressively tunnel through? Previous research has been conflicting.

That quantum tunneling occurs has not been a matter of debate since it was discovered in the 1920s. When IBM famously wrote their name on a nickel substrate using 35 xenon atoms, they used a scanning tunneling microscope to see what they were doing. And tunnel diodes are fast-switching semiconductors that derive their negative resistance from quantum tunneling.

Nonetheless, "Quantum tunneling is one of the most puzzling of quantum phenomena," says Aephraim Steinberg of the Quantum Information Science Program at Canadian Institute for Advanced Research in Toronto to Live Science. Speaking with Scientific American he explains, "It's as though the particle dug a tunnel under the hill and appeared on the other."

Steinberg is a co-author of a study just published in the journal Nature that presents a series of clever experiments that allowed researchers to measure the amount of time it takes tunneling particles to find their way through a barrier. "And it is fantastic that we're now able to actually study it in this way."

Frozen rubidium atoms

Image source: Viktoriia Debopre/Shutterstock/Big Think

One of the difficulties in ascertaining the time it takes for tunneling to occur is knowing precisely when it's begun and when it's finished. The authors of the new study solved this by devising a system based on particles' precession.

Subatomic particles all have magnetic qualities, and they spin, or "precess," like a top when they encounter an external magnetic field. With this in mind, the authors of the study decided to construct a barrier with a magnetic field, causing any particles passing through it to precess as they did so. They wouldn't precess before entering the field or after, so by observing and timing the duration of the particles' precession, the researchers could definitively identify the length of time it took them to tunnel through the barrier.

To construct their barrier, the scientists cooled about 8,000 rubidium atoms to a billionth of a degree above absolute zero. In this state, they form a Bose-Einstein condensate, AKA the fifth-known form of matter. When in this state, atoms slow down and can be clumped together rather than flying around independently at high speeds. (We've written before about a Bose-Einstein experiment in space.)

Using a laser, the researchers pusehd about 2,000 rubidium atoms together in a barrier about 1.3 micrometers thick, endowing it with a pseudo-magnetic field. Compared to a single rubidium atom, this is a very thick wall, comparable to a half a mile deep if you yourself were a foot thick.

With the wall prepared, a second laser nudged individual rubidium atoms toward it. Most of the atoms simply bounced off the barrier, but about 3% of them went right through as hoped. Precise measurement of their precession produced the result: It took them 0.61 milliseconds to get through.

Reactions to the study

Scientists not involved in the research find its results compelling.

"This is a beautiful experiment," according to Igor Litvinyuk of Griffith University in Australia. "Just to do it is a heroic effort." Drew Alton of Augustana University, in South Dakota tells Live Science, "The experiment is a breathtaking technical achievement."

What makes the researchers' results so exceptional is their unambiguity. Says Chad Orzel at Union College in New York, "Their experiment is ingeniously constructed to make it difficult to interpret as anything other than what they say." He calls the research, "one of the best examples you'll see of a thought experiment made real." Litvinyuk agrees: "I see no holes in this."

As for the researchers themselves, enhancements to their experimental apparatus are underway to help them learn more. "We're working on a new measurement where we make the barrier thicker," Steinberg said. In addition, there's also the interesting question of whether or not that 0.61-millisecond trip occurs at a steady rate: "It will be very interesting to see if the atoms' speed is constant or not."

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Image by serato on Shutterstock
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