Jan 5, 2021 09:08 PM
We Know Almost Nothing About Giant Viruses
https://www.theatlantic.com/science/arch...na/617555/
EXCERPTS: Giant viruses, a group discovered only in 2003, are mysteriously large and complex, seemingly between bacteria and the tiny, simple viruses of classical biology. Scientists still don’t know much about what giant viruses do, other than kill amoebas and algae. Leave it to viruses, however, to keep surprising us: Giant viruses don’t just kill their hosts. In some cases, according to a recent study, they can keep their hosts alive and become part of them.
[...] a strange pattern. The viral genes in the algae samples had been subtly altered, as if they were being passed down from generation to generation as part of the algae genome. Giant viruses weren’t simply infecting and killing algae, it seemed; sometimes, they were integrating their DNA into the living algal cell’s DNA. Moniruzzaman and his co-authors ultimately found evidence of giant viruses integrating into 24 of the 65 genomes of green algae they studied. ... All of this suggests that giant viruses play an important role in driving the evolution of their host species -- not just by preying on the weak but also by supplying new genes.
[...] All of this suggests that giant viruses play an important role in driving the evolution of their host species-not just by preying on the weak but also by supplying new genes. [...] What’s unusual about the giant-virus integrations is how big they are. Giant viruses are physically bigger than conventional viruses, and their genomes are substantially longer and more complex. The largest giant virus has a genome of a whopping 2.5 million base pairs. (In comparison, the genome of the coronavirus that causes COVID-19 is only about one-80th as long.)
[...] Much remains unknown about giant viruses as a group. On the basis of the few pieces of the giant-virus puzzle already put together, Suttle estimates that scientists have cataloged only “a small fraction of a percent” of the diversity out there. “So almost nothing,” he adds. Moniruzzaman is now looking for more examples of DNA integration across a broad swath of single-celled organisms, such as fungi and protists, that also might be infected by giant viruses... (MORE - details)
How Much Did Grandmothers Influence Human Evolution?
https://www.smithsonianmag.com/science-n...180976665/
EXCERPT: . . . These observations, which Hawkes and collaborators began in the 1980s, have helped fuel the Grandmother Hypothesis, the idea that grandmothers step in to feed young children and perform other motherly duties so that mothers can focus their own energy and resources on having more children at shorter intervals. The result is that a grandmother enables the birth of more descendants, leaving more copies of her genes in subsequent generations. In prehistoric times, the theory goes, grandmothering led to the spread of genes corresponding to slower aging in women relative to their predecessors, which increased expected lifespans in general.
Combining those observations with models of variation in life history in other organisms, from mice to elephants, Hawkes and colleagues have become convinced that human grandmothers have played a central role in the life history of Homo sapiens. They argue that grandmothers are a driving force behind the increased longevity of our species compared to other primates.
Longevity is also highly correlated with brain size across the mammalian kingdom-the bigger the brain, the longer the lifespan-and the best predictor of brain size is the duration of brain development. “If you’re going to make a bigger brain, it takes longer to make it,” explains Barbara Finlay, professor emerita of psychology at Cornell University, who has collaborated with Hawkes.
Through a combination of anthropological fieldwork, mathematical modeling and comparative primatology, Hawkes and collaborators make the case that a prehistoric division of labor-in which grandmothers take on responsibilities for nourishing grandchildren while mothers pop out more babies-has led to the long lives and big brains we have today. “All of these pieces start to be connected to this puzzle of us, coming back to this life history shift to this increasing longevity, with older females subsidizing the fertility of younger ones,” Hawkes says.
It’s heartwarming to think of grandmothers as evolutionary heroines, especially in the face of an alternative narrative: that postmenopausal women merely represent evolution’s failure to sustain fertility throughout a woman’s entire life. But to skeptics, the Grandmother Hypothesis remains a “just so” story, a tidy narrative that can’t truly be proven or disproven, which is the burden of science. Nonetheless, the Grandmother Hypothesis hints at broader mysteries and controversies about the human lifespan, women’s bodies and to what extent health declines as a result of menopause... (MORE - details)
Could We Populate Another Planet With Genetically Modified Organisms?
https://gizmodo.com/could-we-populate-an...1845955932
INTRO: Earlier this year, a research team made waves by suggesting that we should disseminate Earth’s microbes on Mars in a preemptive effort to foster a climate hospitable to human life. To the “anti-contamination” school of celestial thought, this was heresy; to the most others, this was an obscure theoretical squabble over an issue they’d never heard about. Still, given that our descendants may well spend their most productive years on Mars, it’s worth trying to grasp these early, pre-colonial debates before they assume life-or-death urgency. To that end, for this week’s Giz Asks we’ve posed a two-parter to a number of relevant experts. First: Could we populate another planet with genetically modified organisms? Second: Should we?
Kathryn Denning. [...] We probably could; we probably shouldn’t. But first, it’s worth asking: who’s “we”? Discussion of space and the future often involves a rhetorical “we” that encompasses “all humanity” or “our species.” But it’s time to think differently about space. There is no big “we” here...
[...] John Rummel ... We probably could modify an Earth organism, or suite of organisms, to live in such places for some limited period of time, but I couldn’t guarantee you could “populate” one of those places with GMOs. Unless you were tremendously lucky, the Earth organisms might eat all of the minerals in reach, and then stage a massive die-off that would be tremendously yucky and pointless. And if you were that lucky, there might be native organisms that would just eat your GMO additions and yield a polite “burp” of methane and leave it at that. Right now we don’t know enough to do something useful with GMOs at any alien place (and only a few on Earth)...
[...] Dirk Schulze-Makuch I don’t think we’re there yet, in two senses. We don’t know the environmental conditions of other planets well enough, and we don’t know how to optimally tune the genetic code of an organism to thrive in that extraterrestrial environment. The only planet where I see this as a possibility in the near future is Mars, which we know best of all the planets and moons in our Solar System. But even if we can do it, I don’t think we should. It would be a very human-centric approach...
[...] Nathaniel Szewczyk. Indeed we could. ... it is also fairly easy to send GMO microscopic life forms to other planets. Whether we should is the more difficult question. ... If this is done to allow human habitation of another planet, then potentially all of humanity gains -- whereas those aspects of planetary science that want/need to study a “natural” planet lose out. If this is done to allow for the commercial/financial gain of a few, does that outweigh the loss to science?
[...] Betul Kacar. ... If the candidate planet is in our solar system, such as Mars…perhaps. It becomes a question of: For how much, or how long, are you willing to provide technological assistance to create a habitable volume elsewhere? The engineered organisms will most likely be severely restricted in the range of places they can inhabit. So far as we know, no amount of genetic engineering will enable terrestrial organisms to survive under freezing temperature and extreme soil oxidation conditions, such as those found in the Martian environment... (MORE - details)
https://www.theatlantic.com/science/arch...na/617555/
EXCERPTS: Giant viruses, a group discovered only in 2003, are mysteriously large and complex, seemingly between bacteria and the tiny, simple viruses of classical biology. Scientists still don’t know much about what giant viruses do, other than kill amoebas and algae. Leave it to viruses, however, to keep surprising us: Giant viruses don’t just kill their hosts. In some cases, according to a recent study, they can keep their hosts alive and become part of them.
[...] a strange pattern. The viral genes in the algae samples had been subtly altered, as if they were being passed down from generation to generation as part of the algae genome. Giant viruses weren’t simply infecting and killing algae, it seemed; sometimes, they were integrating their DNA into the living algal cell’s DNA. Moniruzzaman and his co-authors ultimately found evidence of giant viruses integrating into 24 of the 65 genomes of green algae they studied. ... All of this suggests that giant viruses play an important role in driving the evolution of their host species -- not just by preying on the weak but also by supplying new genes.
[...] All of this suggests that giant viruses play an important role in driving the evolution of their host species-not just by preying on the weak but also by supplying new genes. [...] What’s unusual about the giant-virus integrations is how big they are. Giant viruses are physically bigger than conventional viruses, and their genomes are substantially longer and more complex. The largest giant virus has a genome of a whopping 2.5 million base pairs. (In comparison, the genome of the coronavirus that causes COVID-19 is only about one-80th as long.)
[...] Much remains unknown about giant viruses as a group. On the basis of the few pieces of the giant-virus puzzle already put together, Suttle estimates that scientists have cataloged only “a small fraction of a percent” of the diversity out there. “So almost nothing,” he adds. Moniruzzaman is now looking for more examples of DNA integration across a broad swath of single-celled organisms, such as fungi and protists, that also might be infected by giant viruses... (MORE - details)
How Much Did Grandmothers Influence Human Evolution?
https://www.smithsonianmag.com/science-n...180976665/
EXCERPT: . . . These observations, which Hawkes and collaborators began in the 1980s, have helped fuel the Grandmother Hypothesis, the idea that grandmothers step in to feed young children and perform other motherly duties so that mothers can focus their own energy and resources on having more children at shorter intervals. The result is that a grandmother enables the birth of more descendants, leaving more copies of her genes in subsequent generations. In prehistoric times, the theory goes, grandmothering led to the spread of genes corresponding to slower aging in women relative to their predecessors, which increased expected lifespans in general.
Combining those observations with models of variation in life history in other organisms, from mice to elephants, Hawkes and colleagues have become convinced that human grandmothers have played a central role in the life history of Homo sapiens. They argue that grandmothers are a driving force behind the increased longevity of our species compared to other primates.
Longevity is also highly correlated with brain size across the mammalian kingdom-the bigger the brain, the longer the lifespan-and the best predictor of brain size is the duration of brain development. “If you’re going to make a bigger brain, it takes longer to make it,” explains Barbara Finlay, professor emerita of psychology at Cornell University, who has collaborated with Hawkes.
Through a combination of anthropological fieldwork, mathematical modeling and comparative primatology, Hawkes and collaborators make the case that a prehistoric division of labor-in which grandmothers take on responsibilities for nourishing grandchildren while mothers pop out more babies-has led to the long lives and big brains we have today. “All of these pieces start to be connected to this puzzle of us, coming back to this life history shift to this increasing longevity, with older females subsidizing the fertility of younger ones,” Hawkes says.
It’s heartwarming to think of grandmothers as evolutionary heroines, especially in the face of an alternative narrative: that postmenopausal women merely represent evolution’s failure to sustain fertility throughout a woman’s entire life. But to skeptics, the Grandmother Hypothesis remains a “just so” story, a tidy narrative that can’t truly be proven or disproven, which is the burden of science. Nonetheless, the Grandmother Hypothesis hints at broader mysteries and controversies about the human lifespan, women’s bodies and to what extent health declines as a result of menopause... (MORE - details)
Could We Populate Another Planet With Genetically Modified Organisms?
https://gizmodo.com/could-we-populate-an...1845955932
INTRO: Earlier this year, a research team made waves by suggesting that we should disseminate Earth’s microbes on Mars in a preemptive effort to foster a climate hospitable to human life. To the “anti-contamination” school of celestial thought, this was heresy; to the most others, this was an obscure theoretical squabble over an issue they’d never heard about. Still, given that our descendants may well spend their most productive years on Mars, it’s worth trying to grasp these early, pre-colonial debates before they assume life-or-death urgency. To that end, for this week’s Giz Asks we’ve posed a two-parter to a number of relevant experts. First: Could we populate another planet with genetically modified organisms? Second: Should we?
Kathryn Denning. [...] We probably could; we probably shouldn’t. But first, it’s worth asking: who’s “we”? Discussion of space and the future often involves a rhetorical “we” that encompasses “all humanity” or “our species.” But it’s time to think differently about space. There is no big “we” here...
[...] John Rummel ... We probably could modify an Earth organism, or suite of organisms, to live in such places for some limited period of time, but I couldn’t guarantee you could “populate” one of those places with GMOs. Unless you were tremendously lucky, the Earth organisms might eat all of the minerals in reach, and then stage a massive die-off that would be tremendously yucky and pointless. And if you were that lucky, there might be native organisms that would just eat your GMO additions and yield a polite “burp” of methane and leave it at that. Right now we don’t know enough to do something useful with GMOs at any alien place (and only a few on Earth)...
[...] Dirk Schulze-Makuch I don’t think we’re there yet, in two senses. We don’t know the environmental conditions of other planets well enough, and we don’t know how to optimally tune the genetic code of an organism to thrive in that extraterrestrial environment. The only planet where I see this as a possibility in the near future is Mars, which we know best of all the planets and moons in our Solar System. But even if we can do it, I don’t think we should. It would be a very human-centric approach...
[...] Nathaniel Szewczyk. Indeed we could. ... it is also fairly easy to send GMO microscopic life forms to other planets. Whether we should is the more difficult question. ... If this is done to allow human habitation of another planet, then potentially all of humanity gains -- whereas those aspects of planetary science that want/need to study a “natural” planet lose out. If this is done to allow for the commercial/financial gain of a few, does that outweigh the loss to science?
[...] Betul Kacar. ... If the candidate planet is in our solar system, such as Mars…perhaps. It becomes a question of: For how much, or how long, are you willing to provide technological assistance to create a habitable volume elsewhere? The engineered organisms will most likely be severely restricted in the range of places they can inhabit. So far as we know, no amount of genetic engineering will enable terrestrial organisms to survive under freezing temperature and extreme soil oxidation conditions, such as those found in the Martian environment... (MORE - details)