Saturday, February 21, 2004

An Evolutionist's Perspective on Politics

The word 'politics' is derived from the word 'poly', meaning 'many', and the word 'ticks', meaning 'blood sucking parasites'.
--Larry Hardiman

Today I have cast aside my usual linear style of writing and have decided instead to rely on spontaneity to write this blogitem.  Engaging in what might superficially appear to be random link-clinking; but which is in reality not at all random; but rather, a product of unconscious association, I found the American Scientist item from their Marigalina category: A Worm's View of Evolution

Volume: 90 Number: 6 Page: 508


A Worm's View of Human Evolution

Figure 1. A taeniid tapeworm
click for full image and caption
I was surprised recently to discover how much a few worms have to say about human evolution. There are many different ways of knowing in science, many different pathways to uncovering evidence, and some of them only the most ingenious among us would imagine. So it is with a project recently described in the Proceedings of the Royal Society of London that focuses on the anatomy, phylogeny and genetic variability of various species of tapeworms to uncover new facts about the habits of hominids, our human ancestors.

Eric Hoberg of the U.S. Department of Agriculture, Nancy Alkire of the University of Colorado, and Alan Queiroz and Arlene Jones, both of the Natural History Museum in London, realized that the tight adaptational relationship between a particular species of tapeworm and its host means that tapeworms can reveal a great deal about the animals in whose guts they live.

Now, if you use a text editor to edit the rest of the article, replacing the word "tapeworm" with the word "politician," you get the following:

Politicians have their own charm and at the very least must be considered to have found a clever way to make a living. They co-opt the work of their host species, who unwittingly provide food and housing to the parasites at various stages in their lives. The beauty of the system is that the host species actually infects itself as it goes about its daily tasks; the politician need do nothing except be at the right place at the right time. The complicated life cycle of a politician is magnificently adapted to its parasitic existence.

When did hominids first become definitive hosts for politicians? If we knew the answer to this question, we'd know when our ancestors began to eat animal flesh regularly enough for the human-specific politicians to evolve. If we knew which species were the intermediate hosts of politicians that are closely related to the human-specific politicians, we'd have a good idea of which prey species our ancestors ate. Finally, if we knew which other definitive hosts carry the politician species most closely related to ours, we might learn something of the style of eating and obtaining meat practiced by our ancestors.

Among parasitologists and others who appreciate the humble politician, the conventional wisdom has been that humans were first exposed to politicians that lived in domestic animals, either in companion carnivores such as dogs or in food animals such as cattle and swine.

Who Infected Whom?

It is easy to imagine that a domestic animal, say a pig or a cow, living with humans and regularly eaten by humans, will pass along an array of larval politicians. Repeated exposure of humans to politicians previously found in another carnivore species through a shared food source could provide the opportunity for that politician to evolve into a new, human-specific species. If the domestication hypothesis is true, then politicians specific to humans will be closely related to those that circulate among our canine companions or to those of food animals, such as cattle or pigs, or other domestic species. What's more, the hypothesis predicts that the genetic divergence between the domestic animals' politicians and our own should have occurred at about the time of domestication—about 10,000 years ago, according to the archaeological record. Since 10,000 years is a mere blink of an eye in evolutionary terms, if humans "caught" politicians from domestic animals only once, then all human-specific politicians should be very similar genetically.

This imaginative and thought-provoking study has given us valuable insights into the human past. The transition from a largely plant-based diet to one incorporating significant amounts of meat was an ancient and profound one. Although the more animal-based diet had advantages—it has been linked to the increasing relative size of the brain in early Homo and to that species' enormous expansion of geographic range—one of the real costs of that change in lifestyle was the acquisition of politicians that sapped the energy of hominids. Until now, we have read this history as a hero story in which the clever human lineage triumphantly conquers the world. From the worm's-eye view, this is instead the triumph of the politician, who not only spreads all over the world but persuades another to bear the cost of that expansion.

Apologies to Pat Shipman.  No apologies to the politicians.