Archive for the ‘Science’ Category
Extremely interesting article and careful analysis. Quite insightful
Kevin Hartnett reports in Quanta:
It used to be that to find new forms of life, all you had to do was take a walk in the woods. Now it’s not so simple. The most conspicuous organisms have long since been cataloged and fixed on the tree of life, and the ones that remain undiscovered don’t give themselves up easily. You could spend all day by the same watering hole with the best scientific instruments and come up with nothing.
Maybe it’s not surprising, then, that when discoveries do occur, they sometimes come in torrents. Find a different way of looking, and novel forms of life appear everywhere.
A team of microbiologists based at the University of California, Berkeley, recently figured out one such new way of detecting life. At a stroke, their work expanded the number of known types — or phyla — of bacteria by nearly 50 percent, a dramatic change that indicates just how many forms of life on earth have escaped our notice so far.
“Some of the branches in the tree of life had been noted before,” said Chris Brown, a student in the lab of Jill Banfield and lead author of the paper. “With this study we were able to fill in many gaps.”
Life’s Finest Net
As an organizational tool, the tree of life has been around for a long time. Lamarck had his version. Darwin had another. The basic structure of the current tree goes back 40 years to the microbiologist Carl Woese, who divided life into three domains: eukaryotes, which include all plants and animals; bacteria; and archaea, single-celled microorganisms with their own distinct features. After a point, discovery came to hinge on finding new ways of searching.
“We used to think there were just plants and animals,” said Edward Rubin, director of the U.S. Department of Energy’s Joint Genome Institute. “Then we got microscopes, and got microbes. Then we got small levels of DNA sequencing.”
DNA sequencing is at the heart of this current study, though the researchers’ success also owes a debt to more basic technology. . .
I have great difficulty understanding why anyone would reject the theory of evolution since it so clearly explains so many things about organisms and lifeforms. The question of why we are mortal has a clear answer in evolutionary terms, well expressed by Suzanne Sandedin in this answer on Quora to the question “According to the theory of evolution, why do we die?”:
Excellent question. And before I explain the real answer, which is rather mind-bending, here are some previous arguments and why they are wrong.
Myth 1: We die to make room for younger generations.
Genes are selfish, and each individual body is a vehicle for a collection of genes. These genes are selected to favor the survival of copies of themselves. Since parents and offspring use the same resources, the death of a parent creates room ecologically for just one offspring. Each gene in the parent has a 50% chance of appearing in this offspring. But it has a 100% chance of appearing in the parent, because it’s already there. It’s never, then, in the evolutionary interests of a parent to die so an offspring can replace it.
Myth 2: We die because our cells/DNA get damaged with age.
This like saying bad drivers die because of blood loss. It’s a proximate mechanism of death, not the evolutionary cause of mortality.
Our somatic cells (the cells that are part of our body) do indeed suffer occasional mutations as they divide. These mutations can kill or damage cells, which is annoying but not generally a big problem as we can make more. However, the worst mutations do something much more dangerous: they help cells to survive and proliferate. That’s how you get cancer. Because this risk accumulates over time, cells are normally allowed only a limited number of divisions before they undergo cellular senescence, that is, they die. But the genes that cause cellular senescence can also stop working. So that’s one of the ways in which we get old: our somatic cell lineages get older, damaged and mutated, and some become cancerous.
However, the cell/DNA damage idea assumes that this isn’t something evolution can counteract. And that’s clearly false. Lifespan and cancer rates differ between species, and not in the ways you would expect if they were determined by cell/DNA damage. For instance, once you take into account body size and phylogeny, DNA repair doesn’t correlate with lifespan. Lifespan does, however, correlate with ecology: mammal species who typically lead risky lives die younger (even if you protect them from those risks). At one extreme, in the harsh Australian bush we find the male agile antechinus, who dies of stress at the end of a single breeding season. At the other extreme, the naked mole rat can live for three decades in its peaceful underground colonies.
This gets even more puzzling when you start to look at genomics. We have a whole suite of genes devoted to keeping our genome pristine. My favorite is a clever gene called P53 that acts as a “gatekeeper” for cell division. If the cell has too many mutations, P53 will halt division and activate repair mechanisms. If that doesn’t fix things, it will make the cell commit suicide. Mutations that break P53 are involved in about half of all human cancers. Now, here’s the rub: there’s a whole family of genes related to P53 in other mammals, and some work better than others. Naked mole rats, as it happens, have two particularly awesome versions that completely protect them against cancer.
We also know that it’s perfectly feasible for genetic modification to immortalize cell lineages, and that going through a haploid stage is not essential for maintaining cell viability. How do we know this? From the strange case of the 11,000 year old dog. The dog as an individual is long dead, but her cells survive today as an infectious cancer on other dogs’ genitalia. There’s also a quaking aspen in Utah whose roots are at least 80,000 years old.
The same applies to permanent organ damage. Some organs heal and regenerate, some don’t. Some species can regenerate organs that others can’t. A salamander can grow a whole new leg. There’s even a jellyfish that can reverse its development when it’s damaged. All in all, natural selection is clearly capable of creating creatures who can fix cellular and DNA damage and repair damaged organs.
So: evolution can fix these problems for us, and it doesn’t. What the heck, evolution, aren’t we friends?
Well, no, actually, evolution is not our friend. If anything, it’s our genes’ friend. And there’s a very good reason our genes don’t actually care about us. . .
Unfortunately, people in general do not listen to scientists because scientists have spent years—even decades—in study, learning about their specialties, so what do they know? /snark
Victoria Turk writes at Motherboard:
Autonomous weapons are the future’s Kalashnikovs, according to over 1,000 experts in artificial intelligence. Cheap, lethal, and guaranteed to end up in the wrong hands at some point, AI weapons are poised to be at the centre of the next global arms race.
That’s according to an open letter from the Future of Life Institute, an organisation dedicated to mitigating existential risks. It’s endorsed by thousands, including such household names (and outspoken prophets of AI doom) as Stephen Hawking andElon Musk.
“People have argued about autonomous weapons for years,” said Max Tegmark, an MIT professor and one of the FLI’s founders. “This is the AI experts who are building the technology who are speaking up and saying they don’t want anything to do with this.”
He likened the situation to physicists, biologists, and chemists speaking out against research in their fields being used to develop nuclear, biological, and chemical weapons.
Toby Walsh, a professor of AI at the University of South Wales in Australia who will present the letter at the International Joint Conference on Artificial Intelligence in Buenos Aires on Tuesday, said it was time that AI researchers made their stance clear.
“There have been some negotiations at the United Nations in Geneva looking towards some sort of ban on autonomous weapons,” he said. “In conversation with those people, it became to clear to us that it would help the discussions and diplomatic negotiations if they saw that there was general support from scientists and not just humanitarian organisations.”
The letter defines autonomous weapons as those that “select and engage targets without human intervention,” citing as an example “armed quadcopters that can search for and eliminate people meeting certain pre-defined criteria.” It doesn’t include military drones in current use, as a human still has to remotely “pull the trigger.”
Walsh and his many co-signatories are urging authorities to stop an “arms race” for AI-weapons before it really started. “It has been suggested that this potentially will be as big a transformation as the invention of gunpowder and the invention of nuclear weapons to the way we fight war,” Walsh said. . .
It’s happening, and whether we like it or not is irrelevant. But some are in for a big surprise.
A very pleasant little essay in the NY Times by Dave Taft:
Chicory’s flowers are as blue as the summer sky, their casual, untrained beauty heightened by the meager settings in which they grow. One of the best ways to see chicory in New York City is to simply take a drive. The plant seems happiest growing from road medians, cracks in curbs and mangy, un-mowed fields. It grows alongside other beautiful but outcast plants like Queen Anne’s lace, dandelion and soapwort, and it takes only a wet week or two in July to produce a burst of color that can challenge autumn’s leaves.
The brilliant color in such unlikely surroundings can turn the heads of observant urban naturalists, including John Updike: “Show me a piece of land that God forgot — /a strip between an unused sidewalk, say,/and a bulldozed lot, rich in broken glass — /and there, July on, will be chicory.”
Common chicory (Cichorium intybus) is a nonnative plant with a long history serving humans. It is probably best known for the bitter drink which is brewed from its dried and ground roots and is still enjoyed as a coffee substitute, or additive, in many parts of the country. (If you’ve ever been to Café du Monde in the French Quarter of New Orleans, you’re aware of how chicory can elevate a café au lait.) The young leaves are also prized for salads, particularly in Europe, where the plant is not the lowly weed we pass on the parkway, but a specialty crop.
Like any plant with a long history among humans, chicory also has an associated folklore. . .
Evolution produces interesting solutions. Michael Byrne reports at Motherboard:
It’s a shrewd but certainly dark adaptive strategy. The serpentine columbine, a pretty herbaceous plant endemic to California’s wet coastal regions, doesn’t defend against or attack its enemies directly. Instead, it sends out a chemical signal, which attracts random nearby bugs who then detour to the columbine to check things out but suddenly find themselves ensnared on the plant’s “sticky” surfaces—which are leaves and appendages coated with layers of hairlike barbs. These insect passerby, known to biologists as “tourists,” are trapped and eventually die,
The result is that the columbine winds up with a beneficial coating of death. This sheen of corpses is more properly referred to as carrion and it serves to attract carnivorous bugs and spiders, who then unwittingly protect the plant by attacking and-or repelling herbivores that would otherwise pose a threat to the columbine. This strategy, described in the current issue of Ecology, is the only indirect defensive mechanism of its type that’s so-far been observed, though the researchers behind the report note that it may be quite common.
The general idea is known as carrion provisioning. . .