Toxoplasmosis and Humans

Toxoplasmosis is caused by a one celled parasite called Toxoplasma gondii. Generally it wasn’t considered a big deal in humans except in certain circumstances. It could be deadly to fetuses and to people with impaired immune systems.

However, recent research is saying perhaps we should be paying more attention to it. In the US about 11% of people in the US are infected but in some countries the infection rate can be as high as 90%. Typically countries with poor sanitation.

I Will Put a Spell on You

In the 1990s it was discovered that Toxoplasma affected the brains of rats and mice in an interesting way. Infected rodents became less afraid of cats or cat odors and in some cases even seemed to like them. Bad for the mice and rats but good for the Toxoplasma since it needs to go through the cats intestines and come out in its feces as part of its life cycle.

The Toxoplasma seemed to actually rewire the fear center of the rodents’ brains. Since Toxoplasma can also infect primates, mammals and birds, some researchers began wondering about what impact it might have in those groups.

Most of this information is from an article in the New York Times Science section but in another article a few years back, some researchers were looking into a scary possibility in humans. They seemed to be finding that people infected with Toxoplasma had a higher incidence of suicide. I haven’t seen anything more about that.

Recently some scientists wondered about primates and how to test it. Of course, people aren’t worried about getting eaten by house cats. But leopards are a natural predator of chimpanzees. In fact big cats probably ate a fair number of humans as well based on the chew or gnaw marks on bones of human ancestors found in archeological sites.

At a research center in Gabon there was a group of 33 chimpanzees, 9 of which had Toxoplasma. The scientists got urine from leopards, tigers, lions and humans. They then at different times and locations dropped some of the urine onto the fence of the chimpanzees enclosure.

The results are not conclusive but still fascinating. The uninfected chimps tended to avoid the leopard urine and would investigate and smell the other three which are not natural predators of chimpanzees.

On the other hand, the infected chimps tended to go sniff the leopard urine and show little interest in the other three.

The researchers now think that Toxoplasma’s first relationship was with primates and large cats and that since house cats only evolved in the last couple of thousand years, that Toxoplasma found a new vector with house cats and rodents. Crafty little critter for a one celled organism.

Pigs Rout Native Americans

You have probably never read this in history books but pigs and earthworms helped Europeans defeat the Native Americans. (Horses and cows too.) Malaria and other diseases helped quite a bit as well, but that is another story. (This came from reading the book 1493 which the prior post was also about.)

The first English settlers who came to Jamestown came from a land of neatly tended farms. When they came to the Chesapeake and other areas along the East Coast they saw wilderness. It was actually anything but.

Manicured Forests

First, a lot of the land was more densely settled than in England or other parts of Europe. The forests were managed and had been for centuries by regular fires being set to reduce the underbrush. This made hunting and travel much easier. Early Englishmen said the forests looked like English parks. Later the forests became overgrown with underbrush / understory growth as the Europeans disrupted Native American life.

Earthworms to the Attack

There was also a good thick layer of leaf litter. This becomes important because as that decayed it fertilized the trees and other plants. However, when earthworms were introduced by the Europeans, (almost certainly it wasn’t planned, it just happened) they had a dramatic effect. They are apparently very efficient at eating through leaf litter and leaving their droppings. So the layer of leaf liter was quickly reduced and the soils were no longer as rich for the trees or the food crops.

Varying Farming Practices

The Native American “fields” didn’t look like what the Europeans knew and therefore didn’t appreciate them. This was because the fields weren’t monocultures. They consisted of maize, beans and squash growing together.

The beans would grow up the maize and the squash would spread along the ground and protect the roots.

There was also a lot of marsh lands and a plant (called hopniss?) that grew in abundance there had edible tubers. They didn’t taste as good as the Native Americans’ other foods but it was available when those were least abundant and kept the Indians from starving in bad times.

The Europeans looked to alter the landscape to fit their way of life and changed the landscape so there were fewer marshes. Therefore less of the hopniss.

Pigs on a Flanking Attack

But the coup de grace were the farm animals. Many got loose and went wild, especially the pigs. All of them would wander through the Native American fields of maize, beans and squash and either eat them or damage them. The pigs did this but even worse, it turns out that pigs love hopniss (or whatever the plant’s name was) and decimated the areas that the Native Americans had depended on.

Because of these changes, the land could no longer support as many people. Many had also died from European diseases. So many Native Americans pulled up root and headed west without being directly forced to do so.

Indians and Slavery

Perhaps I should say Native Americans and Slavery. In any case, I am reading a book called 1493 which is fascinating. It explores how the movement of people around the world has spread animals, plants, microbes and disease around the world and had a great impact on history and who gained power.

It seems most people on Earth had slavery at some point in their history. The Native Americans practiced it before any Europeans showed up on their shores. There was an interesting split in how it was practiced in the Eastern United States. This is from memory without referencing the book, so minor details might be off.

Slaves in Northern Tribes

The tribes around the Chesapeake Bay and north, Algonquin speaking Indians and others tended to deal with slaves in three ways. Slaves usually came about by capturing people from another tribe that they had battled with. They were either killed to make a point, kept for a while and traded back for tribe members that had been captured by the other tribe or integrated into the tribe that captured them.

Slaves in Southern Tribes

The tribes in the Southeastern United States had a different tradition. When they captured someone from another tribe it tended to be for life and they were treated more harshly.

Guns for Slaves

Apparently the tribes in the South had been disrupted even before Europeans showed up and there was conflict among several major groups. When the Europeans showed up, the Native Americans were interested in their guns, their knives and other metal goods as well as other goods.

The Europeans were looking for labor for the plantations they were setting up. So they traded guns and pots and other items for Native American slaves.

Arms Race

The Native Americans then embarked on an arms race. They didn’t want to be outgunned, so they kept capturing and selling slaves to get more guns so they wouldn’t be outgunned and end up as slaves.

There was the problem that the Native Americans knew the terrain far better than the Europeans and often escaped or in some cases rebelled and killed the Europeans.

There were other reasons as well that the book went into, but it is interesting to note that the geographical divide between the Algonquin Indians in the north and the other tribes in the south is almost exactly the divide of states that banned slavery and the states that embraced slavery.