A Taste for the Beautiful gives an excellent overview of cutting-edge research in the field of sexual selection, Darwin’s second great evolutionary theory after that of natural selection. This field is an important correction of Darwin’s initial views, which were not immediately capable of answering questions on the existence and even elaboration of features that proved both highly attractive form a sexual point of view, that is in view of reproduction, and ruthlessly harmful in terms of survival (the classic example being the peacock’s tail). New research in the discipline is no longer satisfied with solving the apparent paradox of this coexistence of incompatible characteristics or explaining the underlying mechanism of sexual attractiveness, which are now situated in the brain, the most important of our sexual organs, since beauty and attractiveness –the necessary conditions for successful mating and reproduction– are not “essential” or “inherent” properties of creatures, but properties acknowledged by specific and species-related brain functions and constituents. Although all the mysteries concerning beauty recognition are far from being deciphered, contemporary research has witnessed a dramatic shift. Instead of only trying to see how sexual brains evolve in order to become capable of noticing which kind of beauty properties offers the best possible guarantee for a numerous and healthy offspring, recent investigations are also interested in studying how features recognized as beautiful evolve in order to better match the recognizing properties of the brain itself.

Ryan phrases it this way: ”I have a unique perspective to offer on these issues as I have spent the past forty years studying the sexual behavior of a tiny, bumpy frog in Central America. This work has opened my eyes and mind to both the diversity of sexual behavior in the animal kingdom and a core unifying theory that I have developed called sensory exploitation. The key idea is simple: features of the female’s brain that find certain notes of the males’ mating call attractive existed long before those attractive notes evolved. Thus, females are the biological puppeteers, making the males sing exactly what their brains desire. Beauty is indeed in the brain of the beholder, and in most cases, that means the female’s brain (…). This simple idea contributed to a paradigm shift in the study of sexual selection, one in which the importance of the sexual brain as a driver of evolution finally was acknowledged.” (p. 3-4, emphasis by the author).

Ryan’s book gives a lively and very readable survey of this –his and others’– ongoing research. Yet readability and liveliness are not the only qualities of this work. First of all, Ryan is a very meticulous scientist, who tries to divide each question in as many subquestions as possible or necessary. For instance, when discussing sexual attractiveness –for this is how beauty must be encoded in the larger context or reproduction and survival– he makes sharp distinctions between: liking sex, wanting sex, making love, and actual reproduction, linking each type of sexual behavior with specific, sometimes contradictory types of beauty.

Second, he is also a very nuanced and cautious researcher. The perspective he adopts is always a multiple one and he is at great pains taking into account the conflicting outcomes of different types of beauty. To give just one example: in certain species, certain beauty features may attract the eye, ear or nose of the mate(s), but they may for exactly the same reasons also attract possible predators –and even sexually very successful creatures that become food for their enemies do not survive.

Third, Ryan is not a determinist thinker at all. Not only does he accept the limits of the general rules he establishes, always highlighting the existence of exceptions and inconsistencies that he never reduces to just exceptions or mere chance deviations. He is also very keen in admitting blank spaces and following a trial and error method. The frequent “sacrifice” of creatures whose brains are sliced up in order to measure the neurological traces of certain events or experiments is an almost ritual step during any observation and hypothesis cycle. Besides, Ryan is always extremely careful in crediting his colleagues, collaborators, and students of their often crucial contribution to the development of his own work (normally this is formally done in a book’s acknowledgments; here, however, it is tightly woven into the very fabric of the scientific discourse).

Inevitably, the most interesting aspect of A Taste for the Beautiful for nonspecialized readers are the systematic, yet never overemphasized references to human behavior. It would be incorrect to label these references as comparisons with the human species, for this would suppose a separation between man and animal that of course does not exist in this regard. Ryan moves from animal to man and vice versa with a great sense of humor (one has often the impression of assisting the lecture of an enthusiastic professor) and a sound understanding of good old rhetoric. But the bigger picture, that is the brain and the sensory exploitation paradigm is never out of sight, which brings the author to end his book with very interesting remarks on pornography, which he thinks could change our actual ideas and practices of sexuality the “same” way (inverted commas more than simply intended) certain animals he has studied have also modified their features in order to better match what is considered attractive by possible mates.