Book Review: Dark Banquet

This was one of the niftiest books I'd read in awhile. I picked it up in the gift shop at Hot Springs National Park back in September. The author starts off by talking about vampire bats -- the subject of his original Ph.D. research -- but gets into describing a variety of predators and parasites that live on blood. Did you know leeches used to be one of the preferred treatments for hemorrhoids? Physicians would put little silk leashes on the wee beasties to make sure they didn't wander too far afield while fulfilling their therapeutic mission.

The popularity of leeches for treating a wide range of human ailments almost drove one species of leech (Hirudo medicinalis) into extinction in the 18th and 19th centuries. The demand was so great that more leeches were being harvested than the natural reproduction rate could sustain. Fortunately for the leeches, medical practices changed and leeching stopped being viewed as a cure-all for every ailment. Leeches never totally vanished from medicine and are still being used today, but their application is much more specialized.

Interesting though the leeches were, the best part of the book is probably the section on vampire bats. Vampire bats pose all sorts of challenges for researchers. Among other things, they can be remarkably fastidious -- it's hard to keep some species alive in captivity. There's apparently more involved in bat care than just wandering down to the local slaughterhouse and requesting buckets of fresh blood. You also need a flock of donor chickens that the bats can sample occasionally -- maybe there is something to that staple of vampire fiction, the life source or life energies? Characters in vampire novels are always complaining that, yes, it is possible to survive for awhile on bags of blood pilfered from the Red Cross, but it's not enough -- every so often a vampire needs to get its blood from a real live victim.

One thing that surprised me was learning just how tiny the typical vampire bat is. Seeing a drawing of the preferred position of one species while feeding on chickens roosting in a tree makes it pretty clear that the image perpetuated in horror films -- the huge flapping monstrous bats that look like they could suck an ox dry in record time -- is well removed from reality. Vampire bats are tiny. Of course, if you get dozens of the critters all wanting to feed on just one or two animals, the host animal is going to be in trouble pretty quickly. Farmers in Trinidad lose chickens fairly often to vampire bats -- one bat may not take enough blood for the bird to notice, but multiple bats can cause anemia severe enough to kill a hen quickly.

Illustrations in the book are nicely done and do a great job of complementing the text. As science books go, this one was a joy to read and one I'd highly recommend to anyone who has an interest in biology or the natural world.

On a lighter note

Book review: Why Evolution is True

This is one of those great science books that the people who need to read it the most will never touch.  It is, as the dust jacket blurbs promise, a succinct and thorough evaluation of evolutionary theory written in terms a nonscientist can easily understand.  The author, Jerry A. Coyne, summarizes the Charles Darwin's 19th century work in early development of evolutionary theory, lays out the theory's key ideas -- evolution, gradualism, speciation, common ancestry, natural selection, and the recognition that processes other than natural selection can cause evolutionary change -- and then explicates in detail each of those concepts.  The book explains evolution clearly, concisely, and stacks up so much supporting evidence it's guaranteed to make a creationist's head explode.

Coyne begins with the basics:  what is a theory in science?  One of the mantras of the creationists is that evolutionary theory is "just a theory."  Saying that labels the speaker immediately as someone who lacks a basic understanding of science and how science works.  Of course evolutionary theory is just a theory, just as gravitational theory is just a theory; so what?  In science a theory is a possible explanation or collection of related explanations used in an attempt to understand a fact or phenomenon.  Evolution is a fact; the evidence is all around that organisms evolved and continue to evolve; evolutionary theory explains evolution. 

But more than explain a phenomenon, a scientific theory has other properties:  it has to be testable, or potentially falsifible.  In the case of evolutionary theory, when we're surrounded by ongoing, continuous evidence of it happening (pandemic influenza A(H1N1) 2009 being the most recent example to spring to mind), what would falsify it?  Finding fossils known to be from organisms that lived in one distinct geologic era embedded in rock side by side with organisms from another could do it.  An obvious example would be fossilized mammals, which first appeared about 250 million years ago, embedded in geologic strata from a much earlier time period, like the Silurian (over 400 million years ago).  This is one reason some creationists will go to extraordinary lengths to try to prove that humans co-existed with brontosaurs (they apparently think The Flintstones was reality tv). 

Another way to disprove a theory is to use it to make predictions -- and if the predictions don't come true, then the theory may be fatally flawed.  Unfortunately for the doubters, evolutionary theory to date has proved remarkably accurate in its predictions.  A criticism of evolutionary theory used to be that various transitional forms did not exist, e.g., if, as scientists claimed, creatures like whales evolved from land mammals then there should be fossilized whales with legs.  I know a few folks who were quite proud of making that argument 20 or 30 years ago.  Bad news for them:  paleontologists have found a veritable plethora of legged whales, the transitional forms between land mammals and marine.  Evolutionary theory predicted not only that such forms would be found, but in what geologic era.   

In short, Coyne's book explains evolutionary theory and provides numerous examples to support it. The book is extremely readable and loaded with interesting tidbits from the history of science and the natural sciences.  Unfortunately, as Coyne himself admits, even though one would think so much compelling evidence would help to change a few minds, it probably won't.