Despite what you read on the web, having Rh negative
blood does not protect you from HIV infection.

A dangerous rumor has been spreading across the web that people with Rh negative blood are resistant or even immune to getting AIDS. They’re not. This is the “everyone is an expert” ethos of the web at its worst.

I was clued into this rumor through my Ask a Geneticist website. A few months ago I started to get a few questions about whether or not having Rh negative blood protects people from getting infected by HIV, the virus that causes AIDS. I get occasional, random questions like these which I answer and then don’t give a second thought.

But then I started to get more of these questions. And then I got one where someone asked me if being Rh negative was the same as having a CCR5 delta-32 mutation. That woke me up.

Having two copies of the delta-32 version of the CCR5 gene does give some protection from HIV infection. But it has nothing to do with being Rh negative.

Being Rh negative has to do with red blood cells and CCR5 delta-32 with white blood cells. Not only that, but CCR5 and RhD are separate genes on separate chromosomes. (The RhD gene is the gene involved in being Rh negative.)

Clearly the questioner had put two and two together and came up with the answer that CCR5 delta-32 and being Rh negative were the same thing. Which is not the case. I decided to set out and try to find out where this rumor was coming from.

As I talk about here in a previous post about Rh negative blood, I traced it down to a couple of things. One was the supposed mystique associated with being Rh negative. The other had to do with a misunderstanding or misinterpretation of four separate bits of science.

This rumor probably isn’t that big a deal yet. It isn’t like the polio vaccine one in Nigeria that has caused a resurgence of polio there. Or the one about vaccines in general being risky which is at least part of the reason for the whooping cough epidemic here in California.

But if the rumor that being Rh negative protects you from AIDS does take off, then people will get AIDS who otherwise might not have. Rh negative people who do risky things are as likely to get AIDS s anyone else. This is why I wanted to find out what was behind the rumor and try to nip it in the bud.

Hopefully the few people who read what I have written will trust me. I have no axe to grind here and really only care about the truth. Which, unfortunately, is not what a lot of people think about most scientists.

Scientists, along with many other experts, used to be seen as impartial. This is no longer true. In fact, the “everyone has to be an expert” idea probably springs from this general mistrust of authority.

If you don’t trust scientists, then you are going to try to interpret the science yourself. That is hard enough that you may come to the wrong conclusions.

So one answer might be to try to find or create a reliable source of science information. Some place where the scientists involved have no vested interest in the answer.

This used to be universities and the government but that ended long ago. We obviously need something else.

Maybe someone with way too much money like Google needs to set up a foundation where scientists can squash these rumors before they spread. The foundation would have to be independent and receive no outside funding and the scientists would have to work for no one else. This might be enough to give most of the public the confidence they need to trust the answers that come out of the foundation.

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Trying to use DNA to prove the Starchild is half alien.

Let’s say you found a bone and you thought it came from an alien. How could you possibly prove such a thing?

This isn’t something I had given, well, any thought to before but I recently got some questions at Ask a Geneticist about this sort of thing. Which got me to thinking about what it would take to convince me that a bone came from Outer Space.

I guess if you found an intact skeleton that was wildly different from anything on Earth I’d have to take the idea that it came from an alien life form seriously. If you found a skeleton of one of the aliens from Independence Day, for example, that would have to give me pause. (And odds are that aliens would be way weirder than this.)

Another possibility is if you found a bone in some layer where it shouldn’t be. For example, if you found some complicated skeleton in a Pre-Cambrian layer and if you could rule out the many possible trivial explanations, then I might have to believe the skeleton came from elsewhere.

The one thing you almost certainly could not do in these cases is any sort of DNA study. DNA has proven to be a wonderful molecule on which to base life here on Earth but there’s no reason to think that an alien life form would need it.

In fact, if we found alien life that was based on DNA, then that might lend some support for some sort of panspermia model for life on Earth. In other words, life started elsewhere and was seeded here on Earth (and possibly lots of other places too).

What you need for life is something that can make copies of itself almost perfectly*, is stable, and can carry a message. There are probably many different chemicals that fit this bill.

Unfortunately, without knowing something about this alternative genetic material, we probably could not make any sense of it even if it was hiding in some alien bone. Maybe we’d find some sort of chemical that was similar to DNA in that it had lots of repeating units. But we wouldn’t be able to read it. And we’d be hard pressed to figure out how it works without something living to put it into.

Of course, this assumes that whatever molecule stores the alien’s information is stable enough to be found. If the bone was very old, the molecule would have to be much more stable than DNA.

Scientists have gotten very good of late at reading the DNA of long dead creatures. They’ve even managed to piece together all of the DNA of a Neanderthal who lived tens of thousands of years ago. But they can do this because they know how DNA works and can exploit that knowledge to make lots of DNA from the scraps left behind.

Without knowing how the alien storage molecule works, we couldn’t make more of it. Which means there needs to be a whole lot there for us to even get started on understanding it.

What all of this comes down to is that in most cases it would be impossible to use any sort of genetic analysis to prove something was of alien origin. Except for a few rare cases, you’d need to rely on where the bone was found or what the intact skeleton looked like or if it was clutching some bit of advanced technology. The best proof would probably be meeting one in person…

*The almost is key here. You need for there to be some error rate so that evolution and natural selection can happen.

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A scanning electron microscope image of an invisibility cloak recently fabricated by Valentine et al. at UC Berkeley. The inset at lower right shows a close-up of the triangular cloak and the corresponding bump that the experiment worked to conceal. Reprinted by permission from Macmillan Publishers Ltd: Nature Materials 8, 568 – 571, copyright 2009.

While invisibility has been largely the stuff of fiction and allegory, that may only be true a short while longer. Two papers published by groups at UC Berkeley and Cornell have recently demonstrated that objects can now be rendered invisible at wavelengths nearly (but still not quite!) short enough to fool human eyes. The technique has come to be known as optical cloaking.

How does it work? Essentially, cloaking makes an object appear invisible by wrapping the object in a metamaterial designed to bend light. Such bending is common in everyday life, seen for example when you look though a glass of water. The genius of a metamaterial is that it has been carefully crafted to bend light exactly to where it would have gone in the absence of the cloaked object. As a result, both object and cloak are rendered invisible.

In 2006, the first physical version of this concept was demonstrated at Duke in the form of a microwave invisibility cloak. It was not without limitations. Imagine a magic rug that, when wrapped around a standing person, makes the person invisible to only one color, and unfortunately not even a color you can see with bare eyes. You would need something like a radar detector to see how invisible they were. Nevertheless, it was stunning demonstration of the cloaking principle.

The push since this first demonstration has been to extend the properties of this to ever shorter wavelengths, and the Berkeley and Cornell groups (respectively headed by Xiang Zhang and Michal Lipson) have succeeded in doing that with a newly designed "carpet cloak." The new design works quite literally by sweeping an object under a rug. An irregular bump on an otherwise flat conductor is covered with the carpet cloak. Then, when light bounces off both cloak and conductor, the cloak rearranges rays of light to make it appear as if the entire surface were flat.

The cloaks of both groups are at best capable of concealing an object no bigger than a speck of dust, but they make up for it in other areas. The demonstrated cloaks may now hide objects from wavelengths as short as 1,400-1,800 nm. (The microwave cloak above is optimal at about 3.5 cm.) Cut that number down to 700 nm and you truly begin to render objects invisible to human eyes.

The prospect of such technology dazzles the imagination. Could we use such a cloak to hide spy planes? Ugly buildings? UFO landing sites? Jason Valentine, the lead author of the Berkeley group, said that more realistically the new technology could be used to refine defects in expensive electronics. However, because of the mathematical parallels between metamaterials and general relativity, some have even proposed that the new technology be used to test deep space theories related to things such as a black hole's event horizon.

Maybe Alien vs. Harry Potter isn't quite such an awful movie idea after all.

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