What Will Eat You?

QuestionWhat is a “food web?” 

Joel Cohen: A food web is a description of which species living in a place eat which other species. You can think of it like a roadmap with one-way streets. It shows you, if there's an arrow from A to B, it means the energy flows from A to B, or in other words, B eats A, okay? So it's usually drawn with a bunch of circles, you put the name of a species in the circle and then you draw an arrow showing which way the food is flowing. Okay? That's what a food web is. 

Now, we have just been talking about a food web. We've been talking about the food web in which people eat ducks, geese, swine, cattle, okay? And, what most people don't realize is, the things that eat us are the infectious diseases, like the viruses and the bacteria and the worms and the other parasites, much more important than the lions and the tigers. 

And what I've been studying is how the animals we eat put us at risk of being eaten by the infectious agents that eat those animals. So when we eat the duck, it puts us at risk of being eaten by the virus that eats the duck, the H5N1. But let me give you some other examples, okay? The monkeys that live in the forests of west Africa, have long been infected by a virus called the simian influenza—sorry, simian immunodeficiency virus. Okay? SIV. We now believe that people went hunting for those monkeys and either got the blood in their hands or ate them without cooking them fully, and the simian immunodeficiency virus infected the people who were dealing with the blood from those animals and evolved very slightly, because we can compare the genes, and gave us the human immunodeficiency virus, HIV. So by going into a new habitat, eating the monkeys and getting their blood, the things that were eating the monkeys turned to eating us. That's the current understanding of the origin of HIV. It was going after food in the forest. 

Another, okay, do you follow that? We've talked about avian influenza, that's from the expansion into new habitats. Another example is swine flu and trichinosis. We eat the pigs, the worms of trichinosis, if they're not cooked to death and we eat uncooked ham or pork, they start infecting the people. The influenza that swine have infects the people who live with the swine. A last example, mad cow disease. Mad cow disease is a prion that causes bovine spongiform encephalitis, BES. If you eat the flesh of a cow that has been eaten by one of those prions, it will eat you, and then you get Jackob Creutzfeldt disease. 

And, so there's a World Health Organization for animals, did you know that? Probably not.  It's World Organization for Animal Health, it's called, and they have a long list of what are called zoonotic diseases. And a zoonotic disease is a disease that regularly infects vertebrates and will also infect people if they are exposed to it. And many, many, many of those zoonotic diseases are diseases that arise because we raise domestic animals for meat. So there's a connection with the meat and our health that's very close. 

Humans exist in a "food web," wherein we enjoy our familiar menu of plants, vegetables, animals and their by-products, etc; but what’s out there itching to get ahold of us…and how can we stop it?

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Scientists study tattooed corpses, find pigment in lymph nodes

It turns out, that tattoo ink can travel throughout your body and settle in lymph nodes.

17th August 1973: An American tattoo artist working on a client's shoulder. (Photo by F. Roy Kemp/BIPs/Getty Images)
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In the slightly macabre experiment to find out where tattoo ink travels to in the body, French and German researchers recently used synchrotron X-ray fluorescence in four "inked" human cadavers — as well as one without. The results of their 2017 study? Some of the tattoo ink apparently settled in lymph nodes.


Image from the study.

As the authors explain in the study — they hail from Ludwig Maximilian University of Munich, the European Synchrotron Radiation Facility, and the German Federal Institute for Risk Assessment — it would have been unethical to test this on live animals since those creatures would not be able to give permission to be tattooed.

Because of the prevalence of tattoos these days, the researchers wanted to find out if the ink could be harmful in some way.

"The increasing prevalence of tattoos provoked safety concerns with respect to particle distribution and effects inside the human body," they write.

It works like this: Since lymph nodes filter lymph, which is the fluid that carries white blood cells throughout the body in an effort to fight infections that are encountered, that is where some of the ink particles collect.

Image by authors of the study.

Titanium dioxide appears to be the thing that travels. It's a white tattoo ink pigment that's mixed with other colors all the time to control shades.

The study's authors will keep working on this in the meantime.

“In future experiments we will also look into the pigment and heavy metal burden of other, more distant internal organs and tissues in order to track any possible bio-distribution of tattoo ink ingredients throughout the body. The outcome of these investigations not only will be helpful in the assessment of the health risks associated with tattooing but also in the judgment of other exposures such as, e.g., the entrance of TiO2 nanoparticles present in cosmetics at the site of damaged skin."

Why are so many objects in space shaped like discs?

It's one of the most consistent patterns in the unviverse. What causes it?

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  • Spinning discs are everywhere – just look at our solar system, the rings of Saturn, and all the spiral galaxies in the universe.
  • Spinning discs are the result of two things: The force of gravity and a phenomenon in physics called the conservation of angular momentum.
  • Gravity brings matter together; the closer the matter gets, the more it accelerates – much like an ice skater who spins faster and faster the closer their arms get to their body. Then, this spinning cloud collapses due to up and down and diagonal collisions that cancel each other out until the only motion they have in common is the spin – and voila: A flat disc.