An Elegant Defense: The Extraordinary New Science of the Immune System: A Tale in Four Lives

by Matt Richtel

The Black Plague, in the fourteenth century, killed 30 percent or more of Europe’s population. Black or bubonic plague is caused by one of the deadliest pathogens known to man, Yersinia pestis, a flea-borne bacterium named for the man who discovered it in 1894, Alexandre Yersin.

Black or bubonic plague is caused by one of the deadliest pathogens known to man, Yersinia pestis, a flea-borne bacterium named for the man who discovered it in 1894, Alexandre Yersin.

About 8 percent of our genetic material was formed from retroviruses. That means we’ve mingled with these viruses and they’ve become part of us, to the point that they can be not only helpful but essential. An example is the placenta, which may have evolved from a retrovirus in such a way that it helped enable the transmission and sharing of material between mother and child.

salmonella bacterium, for instance, swallowed with food, might use this propulsive tail to burst through the lining of the gut and into the body. It is built to invade.

Approximately 60 million people died in World War II: 15 million on the battlefield, while civilian casualties made up the lion’s share of the deaths, according to the National WWII Museum. That was about 3 percent of the 1940 global population.

A small subset of the mice were observed to spontaneously contract leukemia—whether or not they were irradiated. Scientists noted that this spontaneous occurrence of cancer originated in a small, leaflike organ called the thymus.