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For Further Reading

Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life.

Reference for: Chapter 12, The Foundations of Evolutionary Theory

Haldane, J. B. S. 1932. The Causes of Evolution. Longman: UK.

Reference for: Chapter 12, The Foundations of Evolutionary Theory


*Long, John A. 1995. The Rise of Fishes: 500 Million Years of Evolution. John Hopkins University Press: MD

This lavish overview of the evolution of fishes is not the most detailed but its illustrations and photographs give a rich sense of the evidence on which our understanding of fish evolution is based. It makes a highly readable reference for students and a terrific desk reference for instructors called upon to teach aspects of fish evolution.

Reference for: Chapter 12, Spotlight 12.1

*Raup, David. 1991. Extinction: Bad Genes or Bad Luck? W.W. Norton: NY

This “little” book summarizes the evidence for five major extinctions in the geologic records and their causes. It’s a highly readable and engaging account that will quickly bring the reader up to date on this fascinating topic.

Reference for: Chapter 12, The Foundations of Evolutionary Theory


*Stott, Rebecca. 2003. Darwin and the Barnacle: The Story of One Tiny Creature and History’s Most Spectacular Scientific Breakthrough. Norton: NY

This book brings to the forefront Darwin’s painstaking and highly important work on barnacles. It might be argued that Darwin formulated his ideas about evolution and natural selection from studying barnacles. Although this is a “storybook”, in the sense that it weaves a narrative about Darwin’s barnacle work, it does illuminate this important and little known work in an engaging and instructive manner.

Reference for: Chapter 12, The Foundations of Evolutionary Theory

*Carroll, Sean B. 2006. The Making of the Fittest: DNA and the Ultimate Forensic Record of Evolution. W. W. Norton: NY

The evolutionary record is contained in the DNA of organisms. It is a history that we can finally begin to read.



*Coyne, Jerry A., and H. Allen Orr. 2004. Speciation. Sinauer Associates: MA.

Coyne and Orr have written a textbook covering all aspects of speciation, emphasizing modern research on this topic.


*Ellis, Richard. 2001. Aquagenesis: The Origin and Evolution of Life in the Sea. Viking Penguin Books: NY

Ellis is a masterful storyteller and illustrator. There are better books on this subject but if you like Ellis way of weaving facts, this book should please you.


*Fortey, Richard. 1997. Life: A Natural History of the First Four Billion Years of Life on Earth. Vintage Books: NY

Fortey narrates the history of life on Earth, citing his own work and the research of other scientists to piece together the puzzles of how life evolved.


*Fortey, Richard. 2000. Trilobite! Eyewitness to Evolution. Alfred A. Knopf: NY

All you ever wanted to know about trilobites in an engaging, delightful prose.

*Gould, Stephen Jay. 1989. Wonderful Life: The Burgess Shale and the Nature of History. W. W. Norton: NY

Stephen Jay Gould delights some and irritates others but he always manages to inspire thoughtful reflection on a topic. In this book, he discusses in great detail the Burgess Shale and how it paints a picture of the “progression” of evolution unlike what is commonly perceived. Gould sees evolution not only as “survival of the fittest” but also as “survival of the lucky.”

*Gould, Stephen Jay. 2001. The Book of Life: An Illustrated History of the Evolution of Life on Earth. W.W. Norton: IA

*Gould, Stephen Jay. 2002. The Structure of Evolutionary Theory. Belknap Press of Harvard University Press: MA

This immense volume details Gould’s provocative and often controversial views on the evolution of life on Earth. To his credit, Gould is typically entertaining, and this book reads like a good novel. Unfortunately, you have to read a lot of it if you are generally unfamiliar with his ideas or the nuances of evolution. Nonetheless, it’s an essential reference for a biologist’s library.

*Hull, David L. 2001. Science and Selection: Essays on Biological Evolution and the Philosophy of Science. Cambridge University Press: UK

Hull’s essays educate and entertain and get the reader to thinking more deeply about science and its effects on humanity. His essays on evolution are a big help to those who need a refresher or those who require greater ammunition in the verbal wars with antievolutionists.

*Johnson, Kirk R., and Richard K. Stucky. 1995. Prehistoric Journey: A History of Life on Earth. Roberts Rinehart Publishers: CO.

Based on dioramas at the Denver Museum of Natural History, this delightfully illustrated book traces the history of life from microbes to mammals, with an emphasis on dinosaurs. Its brevity notwithstanding, this book does a great job of providing the fossil evidence on which the scientific interpretation of the history of life is based.

*Kirschner, Marc W. and John C. Gerhart. 2005. The Plausibility of Life: Resolving Darwin’s Dilemma. Yale University Press: CT

Kirscner and Gerhart tackle the origins of new species and evolutionary complexity.

*Knoll, Andrew. 2003. Life on a Young Planet: The First Three Billion Years of Evolution on Earth. Princeton University Press: NJ

This is an outstanding book on the evolution of Earth and its biota. Knoll is one of the pioneers in the field of geobiology and his up-to-date scientific account of the field makes this an excellent reference and an entertaining read. Knoll exposes the controversies and examines the evidence that surrounding them. Most narratives don’t make good reference books but Knoll’s is an exception. If you are trying to choose between “histories of life on Earth”, pick this one.

*Larson, Edward J. 2004. Evolution: The Remarkable History of a Scientific Theory. Modern Library: NY

This book sketches the development of evolutionary theory. It’s primarily written for general audiences and so loses some of the detail required for students and instructors.

*Margulis, Lynn, and Dorion Sagan. 1986. Microcosmos: Four Billion Years of Microbial Evolution. Simon and Schuster: NY.

A provocative hypothesis about the interdependency of higher organisms and bacteria.

*Margulis, Lynn. 1998. The Symbiotic Planet: A New Look at Evolution. Weidenfeld & Nicolson: UK

Margulis is not one to shy away from controversy. Her endosymbiotic hypothesis was met with great skepticism originally but is now widely accepted. In this book, she applies her principles of symbiosis to the full range of life and its communities, including Earth.

*Margulis, Lynn, and Michael F. Dolan. 2002. Early Life: Evolution of the PreCambrian Earth, 2nd Edition. Jones and Bartlett: MA

*Mayr, Ernst. 1982. The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Belknap Press of Harvard University Press: MA

Professor Sean thinks this is one of the most important books ever written. It defends the place of biology in science and retells the history of evolutionary thinking from pre- to neo-Darwinism. At more than 900 pages, it’s an intimidating volume, but Mayr’s prose and his way of explaining concepts makes this book a delight to read. You will only want to read several pages of it at a time as Mayr provokes deep reverie with every page. But you will have a more comprehensive and deeper understanding of evolution upon reading this book than is possible with just about any other book.

*Mayr, Ernst. 2001. What Evolution Is. Basic Books: NY

Any book by Ernst Mayr is worth reading, according to Professor Sean. This book provides a solid foundation for different aspects of evolution and evolutionary processes.

*Weiner, Jonathan. 1994. The Beak of the Finch. Vintage Books: NY

This Pulitzer Prize-winning book has become a textbook for learning about evolution.

*Zimmer, Carl. 1998. At the Water’s Edge: Fish With Fingers, Whales With Legs, and How Life Came Ashore but Then Went Back to Sea. Simon and Schuster: NY

An excellent narrative on macroevolution.

*Zimmer, Carl. 2001. Evolution: The Triumph of an Idea. HarperCollins: NY

This is the companion book to the Evolution video series by PBS.

*Moorehead, Alan. 1969. Darwin and the Beagle. Harper & Row: NY

This “old” book is notable for its abundant photos, illustrations and drawings, many of which are full page and stunning, and for its highly readable and intimate account of Charles Darwin’s voyage aboard HMS Beagle. It’s not as dense with information as other books on Darwin but it captures the spirit of his curiosity and scientific reasoning.

Reference for: Chapter 12, The Foundations of Evolutionary Theory

The Endless Voyage: Building Blocks, Water World and Survivors (written by W. S. Chamberlin) (Episodes 18, 19 and 21). 2002 (VHS and DVD). Intelecom.

Professor Sean appeared in several of the episodes of this series and helped develop learning activities to support it. While some episodes are better than others, The Endless Voyage provides one of the most complete and up-to-date series on oceanography available

: : Encyclopedia of the Sea : :
Chapter Two Image

Cetacean Sexual Behaviors by Sean Chamberlin

Many of the behaviors we have already discussed serve reproductive functions in cetaceans. In this section, we focus on specific behaviors related to courtship and mating. Most of these behaviors involve advertisement communication although tonic communication (“Will you mate with me? Yes I will.”), environmental communication (“I am over here.”) and perhaps even deceptive communication (“I am the most virile.”) may also support these behaviors.

The most popular and best known courting behavior arguably occurs among humpback whales, who engage in an extraordinary acoustic display in which males sing to females. The legendary songs of male humpbacks have graced the soundtrack of many a Hollywood movie ever since Roger Payne and colleagues recorded and published an album called Songs of the Humpback Whale in 1970 (CRM Records). Fixed patterns of sound repeated over time define songs in humpbacks and other animals, especially birds. Whereas the songs of birds may last for seconds with pauses, the songs of humpbacks may last for minutes and continue uninterrupted for hours (stopping to breathe, of course). Payne and McVay (1971) defined the characteristics of humpback songs that researchers still use today. Based on recorded sounds played back at normal speed, they defined a unit as the shortest continuous sound discernible to the human ear (roughly equivalent to a note); a phrase as a series of units (roughly equivalent to a line); a theme as a sequence of similar phrases roughly equivalent to a verse); a song as a combination of several themes (equivalent to a human song made up of a versus, chorus and bridge); and a song session as the repetition of a song with pauses no longer than a minute (roughly equivalent to a concert, albeit one in which only a single song is played!). An individual song may vary in length from 5-30 minutes and may include from three to nine themes. A typical song includes repetition of one theme for several cycles, a switch to another theme and then another and another until all the themes are sung and the song is completed. Then, without interruption, the song is started again and sung in exactly the same manner and order of themes as before “as if on a continuous tape” (Darling 2002). Song sessions may last for hours although the whale may breathe once per song during a particular theme or during a silent interval of the song.

In general, humpback whales sing only during the breeding season, although songs have been occasionally recorded on feeding grounds and during migration. Though most males stay in the same location, some (the very talented ones!) have been observed singing and swimming. During singing, a male humpback will suspend its body head down in about 50-100 feet of water and remain there, surfacing only to breathe. The exact depth at which a humpback sings may be a function of environmental variables—such as seawater temperature or depth of the thermocline—that affect the transmission of sound. Presumably, a humpback whale could adjust its depth to maximize the propagation of sound or to target sound to a particular depth or location, although this hypothesis has not been tested. Alternatively, scattering and “degradation” of different sound frequencies as a result of the environmental could provide sufficient information for a listening whale to determine distance from the vocalizing whale. Different frequencies of sound may serve different purposes as the vocal range in these animals is considerable (Mercado and Frazer 1999).

Within a particular humpback population, such as the Hawaiian population, all males will sing essentially the same song—the same themes in the same order—with only slight variations (Tyack 2000; Darling 2002). Populations in other localities, such as Japan, Mexico and Australia, sing similar albeit distinctive songs, while the songs of Atlantic Ocean populations differ substantially. Scientists hypothesize that intermingling of populations during migration from their breeding to their feeding grounds provides an opportunity for cultural transmission of songs, i.e. it allows their songs to be shared. The most dramatic example of song sharing was observed in two Australian populations, the east coast Pacific population and the west coast Indian Ocean population, whose songs differed considerably prior to 1996. Recordings of these populations between 1995 and 1998 revealed gradual introduction of the Indian Ocean song into the Pacific population in 1996, apparently as a result of the immigration of a few individuals from the Indian Ocean population. By 1998, the Indian Ocean song had completely replaced the original song of the Pacific Ocean population. This extreme example of “cultural revolution” appears unprecedented in the animal kingdom (Noad et al., 2000).

Less dramatic variations in songs are apparent over time—from month to month—and between seasons—from year to year—in any given population of humpback whales. Typically, these variations evolve as exclusion of an old theme or inclusion of a new one. In the Hawaiian Island population, a theme that was popular prior to March 1977 ended in that month and year and has not been heard since. Units of songs or themes may be combined in songs or new elements may be introduced such that by the end of the breeding season (and the end of the song-making season), the song has been changed and incorporated into the repertoire of the entire population. In the parlance of Led Zeppelin, the song remains the same. Despite gradual variations, the songs sung by humpbacks within a particular population remain nearly identical.

At any one time, dozens of humpback males may be singing simultaneously. However, singing individuals are usually separated by several kilometers. If another male joins a singing male, the singing may stop and the two may interact with non-contact agonistic behaviors that include breaching, the leaping of a whale above the surface of the water. Following this interlude, the usually go their separate ways but one or both may start singing again. Alternatively, if a group of whales passes nearby that includes a female, the male may stop singing and join the group. This observation has led some researchers to speculate that singing attracts females but this interpretation has not been universally supported.

A wide number of observations support different aspects of the function of singing in humpback whales. Unfortunately, the one activity that might help to distinguish competing hypotheses—the act of a male humpback mating with a female—has yet to be observed. Singing may serve as a form of advertisement to attract potential mates (Winn and Winn 1978), it may serve as a form of male-male competition to signal size and status (Tyack 2002), it may operate as a floating lek, a kind of breeding-only territory (Clapham 1996) and/or it may serve to space males with enough distance between them so that females can distinguish between individuals. Some researchers suggest it may have multiple functions given that vocalizations may serve many purposes in other cetaceans. Complicating the interpretation is the apparent similarity in songs of males from the same population and the adoption of song variations over time within a population. These observations do not appear to be consistent with an advertisement display aimed at demonstrating “status” or “prowess” whether interpreted by potential mates or male adversaries. Thus, the song of the humpback whale, introduced to popular audiences more than three decades ago, remains a mystery whose function has yet to be ascertained.

Given the apparent enormous investment of time and resources in courtship and selection of mates by male and female cetaceans, you might expect a high degree of fidelity between partners. However, monogamy—the pairing of a male and female within a single breeding season—has never been observed in cetaceans. In fact, it appears that most cetaceans do not mate for life and find new partners year to year. Cetaceans may exhibit what is known as polygamous behavior—mating with multiple individuals but maintain some relationship with those individuals—or promiscuous behavior—mating randomly with multiple partners with whom no permanent relationship is maintained. Considerable evidence for foreplay exists in cetaceans, including buzzing of the genital region, inserting the snout into the genital and touching, stroking, rubbing various parts of the body. Copulation in hetero- and homosexual contexts in immature and mature adults indicates that sex in cetaceans serves functions other than reproduction, such as alliance formation and sex education. The highly sexual nature of at least some species of cetaceans suggests that sex plays a social role, similar to that observed in humans.

The variety of sexual behaviors observed in cetaceans complicates interpretations of the type or types of mating systems. The most commonly defined types of polygamous behavior involve one male mating with multiple females—termed polygyny—or one female mating with multiple males—termed polyandry. However, some species of dolphins may exhibit polygynandry, the multiple mating of both males and females. A study of the testis size, dorsal shape and geographic distribution of 1,678 male spinner dolphins in the eastern Pacific (Stenella longirostris) revealed regional differences that suggest differences in mating systems” the larger-testis whitebelly form likely uses a polgynandrous system while the smaller testis eastern form adopts a polygynous system. Thus, even within a species, different mating systems may be used. Some researchers have suggested that the penis length and testis size are indicative of sperm competition, whereby the sperm of one male dilutes or displaces the sperm of another male. Right, bowhead and gray whales exhibit penis lengths and testis sizes that are large compared to their body size and weight. Observations of multiple matings of right whale males with a single female appear to support this hypothesis (e.g. Whitehead and Mann 2000). While volume of sperm and timing of copulation may be important factors in sperm competition, control of fertilization through estrus—the release of the egg—may also be important. All toothed whales are polyestrous, meaning they may release more than one egg per reproductive cycle. The ability to produce multiple eggs in a reproductive cycle may provide females with greater control over the father of their offspring and may act to reduce infanticide by disguising the identity of the father. Infanticide in primates appears to be aimed at eliminating the competition after the fact. The death of an offspring essentially renders to zero the reproductive success of its father. However, if the father of the offspring is unknown or uncertain—if multiple males mate with a female such that any one of them could be a possible father—then infanticide is less likely to occur because males would not want to risk destroying their own offspring. How and when terrestrial analogues of animal behavior can be applied to cetacean behavior remains in the early stages of scientific progress. The few examples discussed here demonstrate the complexity of cetacean sexual behavior and the difficulty of studying these animals. Nonetheless, it is a rewarding field of research ripe with opportunity for dedicated inquiring minds.