Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures

Some ancient eukaryote swallowed a photosynthesizing bacteria and became a sunlight gathering alga. Millions of years later one of these algae was devoured by a second eukaryote. This new host gutted the alga, casting away its nucleus and its mitochondria, keeping only the chloroplast. That thief of a thief was the ancestor or Plasmodium and Toxoplasma. And this Russian-doll sequence of events explains why you can cure malaria with an antibiotic that kills bacteria: because Plasmodium has a former bacterium inside it doing some vital business.

From Lankaster to Lorenz, scientists have gotten it wrong. Parasites are complex, highly adapted creatures that are at the heart of the story of life. If there hadn't been such high walls dividing scientists who study life - the zoologists, the immunologists, the mathematical biologists, the ecologists - parasites might have been recognized sooner as not disgusting, or at least not merely disgusting. If parasites were so feeble, so lazy, how was it that they could manage to live inside every free-living species and infect billions of people? How could they change with time so that medicines that could once treat them became useless? How could parasites defy vaccines, which could corral brutal killers like smallpox and polio?

parasites make up the majority of species on Earth. According to one estimate, parasites may outnumber free-living species four to one. In other words, the study of life is, for the most part, parasitology. The book in your

It is we who are the parasites, and Earth the host

When Europeans colonized Africa, they helped trigger giant epidemics by forcing people to stay and work in tsetse-infested places. In 1906, Winston Churchill, who was the colonial undersecretary at the time, told the House of Commons that one sleeping sickness epidemic had reduced the population of Uganda from 6.5 million to 2.5 million.