ريتشارد دوكنز's Blog, page 747
June 1, 2015
Do Hunter-Gatherers Smoke Cannabis To Protect Against Worms?
Photo credit:
Jan Havlicek/shutterstock
Smoking a joint might make some feel good, but is that the only reason that people first started smoking cannabis, or did humans start puffing the green herb because it also had medicinal properties? A recent study, published in the American Journal of Human Biology, researchered whether smoking marijuana bestowed isolated hunter-gatherer tribes with health benefits.
Bonobo Study Reveals Our Ancestors Likely Had Less Body Fat and More Muscle Mass
Photo credit:
Edwin Butter/shutterstock.com
The structure of the human body has been shaped by natural selection for nearly five million years. But fossils only include teeth and bones; they lack the muscle, skin, fat, and organs that make up 85 percent of the body. To understand how our body proportions got this way, researchers dissected over a dozen bonobos. Compared to our closest living ape relatives, we have more body fat, and much of our muscle mass was redistributed to our legs.
Newly Discovered Marsupial Will Literally Have Sex Until It Disintegrates
Photo credit:
An Antechinus by Alan Couch / Flickr (CC BY 2.0)
Researchers have discovered two new species of a rare marsupial called the antechinus, and there may still be more species out there. However, they might not be around for much longer. Their destructive sexual habits, alongside deforestation, make them very vulnerable to being wiped out.
Misconception Monday: Viruses Are Not Omnipotent, Part 1
Back in the day, whenOutdoor flu ward, 1918, Walter Reed Hospital
I was the kind of scientist who worked in a lab, I spent seven years deciphering the genetic sequence of the 1918 influenza virus at the Armed Forces Institute of Pathology (AFIP) in Washington D.C. The pandemic caused by this virus, which erupted in three distinct waves beginning in the late summer of 1918 and ending in the spring of 1919, killed somewhere between 20 and 50 million people worldwide. Never before or since has an influenza virus killed so many, nor returned in so many waves so quickly. Could it happen again? Could the outbreaks of avian influenza (subtype H5N2) currently devastating chicken farms in the Midwest lead to 1918-scale disaster?
I don’t think so, and let me tell you why.
It was fear that influenza could cause another devastating pan
Jeff and I, way back when...
demic that drove Jeff Taubenberger and me, and our colleagues at the AFIP, to attempt to isolate viral genetic material of the virus. Our sources were lung biopsies stored in the AFIP’s repository, and later the frozen lungs of an Inuit woman who died of the flu and was buried in permafrost in Brevig Mission, Alaska in the fall of 1918. At the time, it wasn’t known whether it was even possible to isolate and sequence RNA from such old samples; it had never been done.
But the goal—answering questions like, “Where did the virus come from?” and “Why was it was so lethal?”—was so important, we felt we had to try. Long story short: we succeeded. Unfortunately, sequencing the virus’s genes did not provide complete answers to our simple questions about the 1918 pandemic. In fact, the answers remain elusive nearly 10 years later. But that doesn’t mean that we didn’t learn anything. Our work, and that of many other scientists who study influenza, has shed a lot of light on this exceptionally cosmopolitan virus.
I offer this background so that when I tell you that I (and most experts) don’t think this chicken flu (officially called Highly Pathogenic Avian Influenza subtype H5N2, or HPAIH5) will cause a human pandemic, you’ll understand that I’m not completely unqualified to offer such assurances. Viruses, viral evolution, and the factors underlying transmissibilit
Should you be afraid of this chicken?
y and lethality are complicated, but they’re not utterly lawless. And that’s why I get so frustrated when some scientists suggest that because viruses have high mutation rates, they’re basically omnipotent—capable of changing their host range, their mode of transmission and their lethality, seemingly at will. Such claims have been made about not only about bird flu but also about Ebola recently, and I suspect you’ll see this claim emerge (pun intended) in other discussions of newly detected infectious agents. (I wrote about the fears that Ebola would go airborne here).
Now I’m not going to say that viruses can never mutate in ways that enable them to switch hosts, or that result in increased virulence (ability to cause more severe disease). But I will say that it’s far from a given. In fact, it’s pretty unlikely. Viruses—although generally not classified as living things—do share an important characteristic with all living things: they cannot change their characteristics willy-nilly. Viruses cannot evolve on demand, and they’re very specialized, so random mutations are unlikely to be successful, and therefore to spread.
Think about what viruses do—invade cells of another organism and co-opt the cellular machinery to make copies of themselves. This takes considerable precision and specialization. The virus must attach to the cell surface, penetrate th
Typical virus life cycle
e cell wall or membrane, find its way to a place in the cell where it can unpack its genome, subvert the cell’s own DNA, RNA, and protein-making apparati to make all the various viral components, package the various components up again in the right order and proportions, get all the “baby” viruses to the cell’s surface, and then out of the cell where they can go off in search of more host cells. Phew! And all of this while evading or at least delaying the host’s immune response long enough to accomplish the whole replication cycle.
It’s sort of amazing that viruses work at all. In my view, the fact that they do what they do, given their tiny size and relatively simple structures, is impressive and fascinating. Like all other biological systems, the interaction between host and virus is both complex and highly specific. A long evolutionary battle has honed each virus’s individual strategy—and this evolutionarily fine-tuned specificity is precisely why chicken-adapted flu strains are highly unlikely to jump to humans, something I’ll talk more about in Part 2.
Answer Monday
Last week we looked at a pretty old, pretty big fossil. I suppose if you think on the dinosaur scale it wasn’t that big. But I’m more of a microbiologist, so bear with me—to me, any organism you have to measure in meters is huge. Readers had lots of ideas about what this creature might be, but only one person came close. That's because pinpoint identification of this critter continues to elude even the experts. Let's take a closer look:
The best I can tell you about this particular specimen is that it’s a Phyllocarid, but as all the Phyllocarid fanatics out there know, this hardly narrows things down.
Some firmer information. This particular fossil is rare both for its size and its composition. The organism was a pretty big Phyllocarid, and its degree of soft tissue preservation is unusual. Typically with Phyllocarids from this period, you only see the big hard shell at the front: not the long, trailing, relatively soft body. This specimen was found alongside many other currently unidentified fossils; a rich view into the sea of a time we can’t yet fully describe.
All mystery aside, what’s important to note is that this organism was a crustacean, and frankly, it looks like it was probably delicious. Picture a meter-long, prehistoric shrimp! Definitely the kind of organism we wish was still around today.
The winner this week? A reader who goes by the handle "gazzang". Congratulations, and thanks for playing! If you have a fossil you want to share, send your pictures to me at schoerning@ncse.com. And if you need another fossil fix, check out the UIowa Palentology Repository, who we thank for this week's fossil!
World must confront jihadism’s roots in Islamic doctrine, says author
by JP O’ Malley
When Sam Harris speaks his mind people tend to listen, regardless of whether they agree with him or not. Take his controversial appearance last October on the prime time HBO television show, “Real Time with Bill Maher.”
Harris began a conversation that night by claiming Western liberals have failed abysmally when it comes to challenging theocracy in the Muslim world.
“Liberals will criticize Christians,” announced Harris to the studio audience. “But when you want to talk about homosexuals and free thinkers in the Muslim world, liberals have failed us. We have been sold this meme of Islamophobia, where every criticism about the doctrine of Islam somehow gets conflated with bigotry of Muslims as people. And intellectually, that is just ridiculous,” concluded Harris that night.
Actor Ben Affleck, also a guest on the program, weighed in. His voice tight with anger, he called Harris’s ideas “gross” and “racist.” The clip now has over 2 million hits on YouTube.
Read the full article by clicking the name of the source located below.
May 31, 2015
Letter from Brazil, Part 3
by Richard Dawkins
Back in São Paulo airport, 24 hours on
Well, vus don’t come much more déjà than this. Back in the airport, waiting for exactly the same plane displaced by 24 hours, having spent the day, at American Airlines’ expense, in an airport hotel almost entirely populated by air crews of many different airlines, clad in a wonderful variety of liveries.
I admit to being overcome with emotion in the face of human kindness. Thank you, Brazilian employees of American Airlines. I was a bit tetchy with you last night when you wouldn’t let me on the plane. But you were obviously right. And this evening, when I arrived, such kindness, such care. As soon as I approached the American Airlines check-in desk I was pounced on by two women, who had obviously been briefed to look out for me (how did they recognise me, I don’t for a moment wonder). One of them VIPd me through security – and this really mattered because I had surrendered the all important immigration/emigration document last night and would have had trouble with the passport authorities. At every stage, the American Airlines women have been kind and solicitous, apparently alerted to what happened last night by some internal grapevine . Thank you for your humanity.
Rogue Antimatter Found in Thunderclouds
By Davide Castelvecchi
When Joseph Dwyer’s aeroplane took a wrong turn into a thundercloud, the mistake paid off: the atmospheric physicist flew not only through a frightening storm but also into an unexpected—and mysterious—haze of antimatter.
Although powerful storms have been known to produce positrons—the antimatter versions of electrons—the antimatter observed by Dwyer and his team cannot be explained by any known processes, they say. “This was so strange that we sat on this observation for several years,” says Dwyer, who is at the University of New Hampshire in Durham.
The flight took place six years ago, but the team is only now reporting the result (J. R. Dwyer et al. J. Plasma Phys.; in the press). “The observation is a puzzle,” says Michael Briggs, a physicist at the NASA Marshall Space Flight Center in Huntsville, Alabama, who was not involved in the report.
A key feature of antimatter is that when a particle of it makes contact with its ordinary-matter counterpart, both are instantly transformed into other particles in a process known as annihilation. This makes antimatter exceedingly rare. However, it has long been known that positrons are produced by the decay of radioactive atoms and by astrophysical phenomena, such as cosmic rays plunging into the atmosphere from outer space. In the past decade, research by Dwyer and others has shown that storms also produce positrons, as well as highly energetic photons, or γ-rays.
Read the full article by clicking the name of the source located below.
Southern Baptist leader endorses secularist campaign
By Bob Allen
A Southern Baptist seminary president has added his blessing to a campaign advocating for atheists.
Danny Akin, president of Southeastern Baptist Theological Seminary in Wake Forest, N.C., affirmed Openly Secular, a campaign fighting discrimination against people based upon their non-belief, in a two-minute video message posted online.
“You are probably wondering immediately: why would I be doing a video at the site of Openly Secular?” Akin said in the video. “The reason is that though we do disagree about some very important issues, we also agree about some important things as well.”
“For example, we do believe, together, that no one should be coerced when it comes to their particular religious beliefs,” Akin continued. “Whether they are religious or not religious, they should have the freedom to express what they believe and they should be able to do so without hatred, without discrimination. They should not be put down because they happen to disagree with another person in terms of what they believe.
Read the full article by clicking the name of the source located below.
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