March 2005

'The Evolution Explosion' by Stephen R. Palumbi

This months choice for book of the month is "The Evolution Explosion: How Humans Cause Rapid Evolutionary Change" by Stephen R. Palumbi. Palumbi is a biology professor at Harvard University, and is involved in teaching evolution, marine biology, and molecular ecology. With this kind of background, he seems primed to take on the discussion of evolution, and this book doesn't disappoint the reader. The overall treatment of the writing seems to be as if Palumbi was giving a classroom lecture; he even admits to using the same concepts with his students in class. In a way, this is a good thing, because he has a story to tell, but he needs to lay an accurate foundation for the plot. This is a fairly quick read, though, and can probably be enjoyed over a nice weekend of reading.

From the Mountains to the Sea

This chapter is pretty much an introduction for the book. Palumbi opens up with a short tale about an experience with a colleague in Hawaii, and sets up the premise for the book. Most of the rapid change in evolution mentioned in this book concerns diseases, be it HIV/AIDS or tuberculosis.

Right Before Your Eyes

It's hard to imagine that evolution is something that we can observe in our own lifetimes, given the notion that it's generally said to require long periods of time. What's even harder to imagine is that anyone can ignore that evolution happens in the first place. This chapter gets into the history of evolution, starting with Darwin. Darwin suggested that evolution happens through natural selection, and implied this happened over a long period of time. Naturally, the assumptions people made about evolution is that would take more time than can be studied, so while they accepted that it could happen, they didn't expect to see it within their lifetime. The notion of rapid evolution, evolution that happens in a relatively short amount of time, isn't a new concept to Palumbi, however. Studies regarding bacteria, guppies, and a number of other organisms show us that evolution can happen in a short amount of time, and lead to drastic changes.

The Engine of Evolution

Palumbi opens up this chapter with an analogy about cookies brought by parents to school social functions. He uses this as a tool to describe variation, and notes that homemade cookes, with more variation and not being prepackaged showing variation, are always chosen first. This illustrates an engine of evolution: natural selection. This chapter is pretty much a primer on how natural selection works, and Palumbi gives numerous examples to illustrate the lesson.

Temporary Miracles: The Evolution of Antibiotic Resistance

Probably the most recognizable human-influenced evolution is in the use of antibiotics. When they were first discovered, antibiotics were thought to be the end of diseases around the world. Doctors would prescribe things like penicillin to treat just about any infectious non-viral disease (and maybe some viral diseases as well, despite that antibiotics would have no effect). Little did they know that the process of evolution would drive many organisms into developing resistance to antibiotics, however. In this chapter, Palumbie describes and details various antibiotics, and how resistance to them has occured. It is because evolution with regards to resistance to antibiotics happens so fast, that nowadays, doctors use antibiotics as little as possible, to prevent resistant strains.

The Evolution of HIV

If you were to ask people living today what they thought the most serious disease that affects the world is, most would probably respond with HIV/AIDS. Palumbi singles out HIV in this chapter because of a few reasons, and they all deal with evolution. HIV, by its very nature, as Palumbi points out, isn't very good at making copies of itself. This means that there are many varieites of HIV possible. This high rate of variability is one of the reasons that HIV is so hard to fight, as well. Most astonishing (at least to me) is when Palumbi points out that even within a single person there can be different varieties of HIV. This chapter provides some interesting, and disturbing, information about one of the great epidemics of our time.

Poisoning Insects and What They Can Do About It

Palumbi moves from the microscopic the macroscopic in this chapter. Another very visible way to see how humans impact evolution is in pesticide resistance among insects. This chapter talks about how the use of pesticides has driven the evolution of resistant strains of insects around the world. This has a very real consequence, as insects damaging crops and commodities can potentially affect the entire population.

Biotechnology and the Chemical Plow

Farmers use more than just pesticides to keep their crops growing. Another, probably more popular practice among farmers, involves the use of herbicides. These chemical compounds do what the name implies: they kill plants. It seems a little strange to use something that kills plants to help plants grow, but herbicides are widely used, and often better to use than pesticides. In this chapter, Palumbi relates the story of how pest weeds, such as jointed goatgrass (Aegilops cylindrica), which, like many insects, have evolved resistance to herbicides, and threaten crops grown by farmers to help feed the world.

Evolution All at Sea

Overfishing (and overlobstering...) have played a dramatic role in the evolution of sea creatures. We harvest the biggest, largest, longest fish we can. We have raised some of them to grow fast, many times before they reach reproductive age. Legislators place limitations on which types of fish and marine life one can keep when they're caught, and which ones you'd have to release. What we do when we use this selective process is create an artificial mechanism that drives evolution. As a result, really big catches have declined, large lobsters are a rarity, and the small fry we've generated by this artificial selection are slipping, literally, through fishermen's nets. Palumbi discusses the topic of selection by humans and their role in the evolution of marine creatures in this chapter, and discusses salmon, lobsters, and other marine organisms we now consider as delicacies.

Are Humans Still Evolving?

As Palumbi asks in the title of this chapter, are humans still evolving? Many people accept that, at least on some level, evolution occurs, but fail to acknowledge or recognize that humans are included in the sphere of life on Earth, and are affected by the same general kinds of pressures that other organisms do. In other words, humans, indeedm are evolving, despite those that believe otherwise. In this chapter, Palumbi discusses several diseases, such as cholera, that should be wiped out by natural selection, but still persist, even in modernizzed countries. Palumbi contends and supports that some diseases, while potentially harmful, can sometimes be more beneficial than some other diseases. A specific example he uses in this chapter is the relationship between cystic fibrosis (CF) and cholera. CF, a terrible and often devastating disease, affects the lungs, guts, and pancreas of the human body. One of the early symptoms of CF is salty sweat, because it causes excessive loss of salt through sweat. Cholera, a type of bacteria, produces a toxin which causes cells, and eventually people, to dehydrate. CF can play a role in keeping cholera at bay, and this is a suggestion of why CF still persists in humans, because it helps fight off the effects of cholera.

The Ecology and Evolution of Aloha

This final chapter examines the role of cultural change in the evolution of human society. Palumbi makes a comparison between looking at hundreds of generations of flies to note the evolutionary change that might have occured, and the number of generations humans have had since the first written alphabet, and how far our culture has come since then. This analog is used to illustrate that humans are evolving not just physically, but socially as well. While this may or may not fit a biological definition for evolution, the change our society has had over time has had a dramatic effect on both humans, and the rest of the world we live in, and depend on. If we truly are the stewards of the planet, will this realization change our role in the evolution of other organisms?

Summary

Palumbi does an excellent job of putting evolution into perspective in this book. Instead of taking the general route that some authors use in discussing evolution, he uses humans as a driving factor in evolution. Because of this, he has created a unique book that illustrates just how much we impact the world we live in. This is a great book, a quick weekend read, and something most people interested in evolution should enjoy.