In musical terminology, tempo ("time" in Italian) is the speed or pace of a given piece. In classical music, tempo is typically indicated with an instruction at the start of a piece (often using conventional Italian terms) and is usually measured in beats per minute (or bpm). In modern classical compositions, a "metronome mark" in beats per minute may supplement or replace the normal tempo marking, while in modern genres like electronic dance music, tempo will typically simply be stated in bpm.
Tempo may be separated from articulation and meter, or these aspects may be indicated along with tempo, all contributing to the overall texture. While the ability to hold a steady tempo is a vital skill for a musical performer, tempo is changeable. Depending on the genre of a piece of music and the performers' interpretation, a piece may be played with slight tempo rubato or drastic accelerando. In ensembles, the tempo is often indicated by a conductor or by one of the instrumentalists, for instance the drummer.
While tempo is described or indicated in many different ways, including with a range of words (e.g., "Slowly", "Adagio" and so on), it is typically measured in beats per minute (bpm or BPM). For example, a tempo of 60 beats per minute signifies one beat per second, while a tempo of 120 beats per minute is twice as rapid, signifying one beat every 0.5 seconds. The note value of a beat will typically be that indicated by the denominator of the time signature. For instance, in 4
4 the beat will be a crotchet, or quarter note.
This measurement and indication of tempo became increasingly popular during the first half of the 19th century, after Johann Nepomuk Maelzel invented the metronome. Beethoven was one of the first composers to use the metronome; in the 1810s he published metronomic indications for the eight symphonies he had composed up to that time.
Instead of beats per minute, some 20th-century classical composers (e.g., Béla Bartók, Alberto Ginastera, and John Cage) specify the total playing time for a piece, from which the performer can derive tempo.
With the advent of modern electronics, bpm became an extremely precise measure. Music sequencers use the bpm system to denote tempo. In popular music genres such as electronic dance music, accurate knowledge of a tune's bpm is important to DJs for the purposes of beatmatching.
The speed of a piece of music can also be gauged according to measures per minute (mpm) or bars per minute, the number of measures of the piece performed in one minute. This measure is commonly used in ballroom dance music.
In different musical contexts, different instrumental musicians, singers, conductors, bandleaders, music directors or other individuals will select the tempo of a song or piece. In a popular music or traditional music group or band, the bandleader or lead singer may select the tempo. In popular and traditional music, whoever is setting the tempo often counts out one or two bars in tempo. In some songs or pieces in which a singer or solo instrumentalist begins the work with a solo introduction (prior to the start of the full group), the tempo they set will provide the tempo for the group. In an orchestra or concert band, the conductor normally sets the tempo. In a marching band, the drum major may set the tempo. In a sound recording, in some cases a record producer may set the tempo for a song (although this would be less likely with an experienced bandleader).
In classical music it is customary to describe the tempo of a piece by one or more words, most commonly in Italian, in addition to or instead of a metronome mark in beats per minute. Italian is typically used because it was the language of most composers during the time these descriptions became commonplace. Some well-known Italian tempo indications include "Allegro", "Andante" and "Presto".This practice developed during the 17th and 18th centuries, the baroque and classical periods. In the earlier Renaissance music, performers understood most music to flow at a tempo defined by the tactus (roughly the rate of the human heartbeat). The mensural time signature indicated which note value corresponded to the tactus.
In the Baroque period, pieces would typically be given an indication, which might be a tempo marking (e.g. Allegro), or the name of a dance (e.g. Allemande or Sarabande), the latter being an indication both of tempo and of metre. Any musician of the time was expected to know how to interpret these markings based on custom and experience. In some cases, however, these markings were simply omitted. For example, the first movement of Bach's Brandenburg Concerto No. 3 has no tempo or mood indication whatsoever. Despite the increasing number of explicit tempo markings, musicians still observe conventions, expecting a minuet to be at a fairly stately tempo, slower than a Viennese waltz; a perpetuum mobile quite fast, and so on. Genres imply tempos. Thus, Ludwig van Beethoven wrote "In tempo d'un Menuetto" over the first movement of his Piano Sonata Op. 54, though that movement is not a minuet.
Many tempo markings also indicate mood and expression. For example, presto and allegro both indicate a speedy execution (presto being faster), but allegro also connotes joy (from its original meaning in Italian). Presto, on the other hand, simply indicates speed. Additional Italian words also indicate tempo and mood. For example, the "agitato" in the Allegro agitato of the last movement of George Gershwin's piano concerto in F has both a tempo indication (undoubtedly faster than a usual Allegro) and a mood indication ("agitated").
Often a particular musical form or genre implies its own tempo, so composers need place no further explanation in the score. Popular music charts use terms such as bossa nova, ballad, and Latin rock in much the same way. Lead sheets and fake book music for jazz or popular music may use several terms, and may include a tempo term and a genre term, such as "slow blues", "medium shuffle" or "fast rock".
Here follows a list of common tempo markings. The beats per minute (bpm) values are very rough approximations for 4
These terms have also been used inconsistently through time and in different geographical areas. One striking example is that Allegretto hastened as a tempo from the 18th to the 19th century: originally it was just above Andante, instead of just below Allegro as it is now. As another example, a modern largo is slower than an adagio, but in the Baroque period it was faster.
From slowest to fastest:
Several composers have written markings in French, among them baroque composers François Couperin and Jean-Philippe Rameau as well as Claude Debussy, Olivier Messiaen, Maurice Ravel and Alexander Scriabin. Common tempo markings in French are:
Many composers have used German tempo markings. Typical German tempo markings are:
One of the first German composers to use tempo markings in his native language was Ludwig van Beethoven. The one using the most elaborate combined tempo and mood markings was probably Gustav Mahler. For example, the second movement of his Symphony No. 9 is marked Im Tempo eines gemächlichen Ländlers, etwas täppisch und sehr derb, indicating a slowish folk-dance-like movement, with some awkwardness and much vulgarity in the execution. Mahler would also sometimes combine German tempo markings with traditional Italian markings, as in the first movement of his sixth symphony, marked Allegro energico, ma non troppo. Heftig, aber markig (Energetically quick, but not too much. Violent, but vigorous).
English indications, for example quickly, have also been used, by Benjamin Britten and Percy Grainger, among many others. In jazz and popular music lead sheets and fake book charts, terms like "fast", "laid back", "steady rock", "medium", "medium-up", "ballad", "brisk", "brightly" "up", "slowly", and similar style indications may appear. In some lead sheets and fake books, both tempo and genre are indicated, e.g., "slow blues", "fast swing", or "medium Latin". The genre indications help rhythm section instrumentalists use the correct style. For example, if a song says "medium shuffle", the drummer plays a shuffle drum pattern; if it says "fast boogie-woogie", the piano player plays a boogie-woogie bassline.
Humourist Tom Lehrer uses facetious English tempo markings in his anthology Too Many Songs by Tom Lehrer. For example, "National Brotherhood Week" is to be played "fraternally"; "We Will All Go Together" is marked "eschatologically"; and "Masochism Tango" has the tempo "painstakingly".
Tempo is not necessarily fixed. Within a piece (or within a movement of a longer work), a composer may indicate a complete change of tempo, often by using a double bar and introducing a new tempo indication, often with a new time signature and/or key signature.
It is also possible to indicate a more or less gradual change in tempo, for instance with an accelerando (speeding up) or ritardando (rit., slowing down) marking. Indeed, some compositions chiefly comprise accelerando passages, for instance Monti's Csárdás, or the Russian Civil War song Echelon Song.
Composers may use expressive marks to adjust the tempo:
While the base tempo indication (such as Allegro) typically appears in large type above the staff, adjustments typically appear below the staff or, in the case of keyboard instruments, in the middle of the grand staff.
They generally designate a gradual change in tempo; for immediate tempo shifts, composers normally just provide the designation for the new tempo. (Note, however, that when Più mosso or Meno mosso appears in large type above the staff, it functions as a new tempo, and thus implies an immediate change.) Several terms, e.g., assai, molto, poco, subito, control how large and how gradual a change should be (see common qualifiers).
After a tempo change, a composer may return to a previous tempo in two ways:
These terms also indicate an immediate, not a gradual, tempo change. Although they are Italian, composers tend to employ them even if they have written their initial tempo marking in another language.
While many composers have retained traditional tempo markings, sometimes requiring greater precision than in any preceding period, others have begun to question basic assumptions of the classical tradition like the idea of a consistent, unified, repeatable tempo. Graphic scores show tempo and rhythm in a variety of ways. Polytemporal compositions deliberately utilise performers playing at marginally different speeds. John Cage's compositions approach tempo in diverse ways. For instance 4′33″ has a defined duration, but no actual notes, while As Slow as Possible has defined proportions but no defined duration, with one performance intended to last 639 years.
More extreme tempos are achievable at the same underlying tempo with very fast drum patterns, often expressed as drum rolls. Such compositions often exhibit a much slower underlying tempo, but may increase the tempo by adding additional percussive beats. Extreme metal subgenres such as speedcore and grindcore often strive to reach unusually fast tempo. The use of extreme tempo was very common in the fast bebop jazz from the 1940s and 1950s. A common jazz tune such as "Cherokee" was often performed at quarter note equal to or sometimes exceeding 368 bpm. Some of Charlie Parker's famous tunes ("Bebop", "Shaw Nuff") have been performed at 380 bpm plus.
In popular music genres such as disco, house music and electronic dance music, beatmatching is a technique that DJs use that involves speeding up or slowing down a record (or CDJ player, a speed-adjustable CD player for DJ use) to match the tempo of a previous or subsequent track, so both can be seamlessly mixed. Having beatmatched two songs, the DJ can either seamlessly cross fade from one song to another, or play both tracks simultaneously, creating a layered effect.
DJs often beatmatch the underlying tempos of recordings, rather than their strict bpm value suggested by the kick drum, particularly when dealing with high tempo tracks. A 240 bpm track, for example, matches the beat of a 120 bpm track without slowing down or speeding up, because both have an underlying tempo of 120 quarter notes per minute. Thus, some soul music (around 75–90 bpm) mixes well with a drum and bass beat (from 150–185 bpm). When speeding up or slowing down a record on a turntable, the pitch and tempo of a track are linked: spinning a disc 10% faster makes both pitch and tempo 10% higher. Software processing to change the pitch without changing the tempo, or vice versa, is called time-stretching or pitch-shifting. While it works fairly well for small adjustments (± 20%), the result can be noisy and unmusical for larger changes.
3.2 The tempi for each dance shall be: Waltz 28‒30 bars/min, Tango 31‒33 bars/min, Viennese Waltz 58‒60 bars/min, Slow Foxtrot 28‒30 bars/min, Quickstep 50‒52 bars/min; Samba 50‒52 bars/min, Cha-Cha-Cha 30‒32 bars/min, Rumba 25‒27 bars/min, Paso Doble 60‒62 bars/min, Jive 42‒44 bars/min.
Books on tempo in music:
Examples of musical scores:
Além do Tempo (English title: Time After Time) is a Brazilian telenovela that premiered on 13 July 2015 and ended 15 January 2016. It is created by Elizabeth Jhin. Written by Elizabeth
Jhin in conjunction with Eliane Garcia, Lílian Garcia, Duba Elia, Vinícius Vianna, Wagner de Assis and Renata Jhin; Além do Tempo is directed by Pedro Vasconcelos and Rogério Gomes. Starring Alinne Moraes, Rafael Cardoso, Paolla Oliveira, Ana Beatriz Nogueira, Emilio Dantas, Irene Ravache, Letícia Persiles and Júlia Lemmertz.Chill-out music
Chill-out (shortened as chill; also typeset as chillout or chill out) is a loosely defined form of popular music characterized by slow tempos and relaxed moods. The definition of "chill-out music" has evolved throughout the decades, and generally refers to anything that might be identified as a modern type of easy listening. Some of the genres associated with "chill" include downtempo, classical, dance, jazz, hip hop, world, pop, lounge, and ambient.
The term was originally conflated with "ambient house" and came from an area called "The White Room" at the Heaven nightclub in London in 1989. By playing ambient mixes from sources such as Brian Eno and Mike Oldfield, the room allowed dancers a place to "chill out" from the faster-paced music of the main dance floor. Ambient house became widely popular over the next decade before it declined due to market saturation. In the early 2000s, DJs in Ibiza's Café Del Mar began creating ambient house mixes that drew on jazz, classical, Hispanic, and New Age sources. The popularity of chill-out subsequently expanded to dedicated satellite radio channels, outdoor festivals, and thousands of compilation albums. "Chill-out" was also removed from its ambient origins and became its own distinct genre.
"Chillwave" was an ironic term coined in 2009 for music that could already be described with existing labels such as dream pop. Despite the facetious intent behind the term, chillwave was the subject of serious, analytical articles by mainstream newspapers, and became one of the first genres to acquire an identity online. As on-demand music streaming services grew in the 2010s, a form of downtempo tagged as "lo-fi hip hop" or "chillhop" became popular among YouTube users.Cyfluthrin
Cyfluthrin is a pyrethroid insecticide and common household pesticide. It is a complex organic compound and the commercial product is sold as a mixture of isomers. Like most pyrethroids, it is highly toxic to fish and invertebrates, but it is far less toxic to humans. It is generally supplied as a 10–25% liquid concentrate for commercial use and is diluted prior to spraying onto agricultural crops and outbuildings.DirecTV-5
DIRECTV-5 is a communications satellite launched from Baikonur Cosmodrome, Kazakhstan in May, 2002 to provide mainly Spanish language satellite television programs to DirecTV customers from the 119 degrees West longitudinal orbit. It was built by Space Systems/Loral, as part of its LS-1300 line. In May 2004, DIRECTV successfully launched DIRECTV 7S, their second high powered spot beam. DIRECTV 7S is located at the 119 degree orbital slot.
DirecTV-5 was originally known as Tempo 1, and was originally intended for satellite provider ASkyB, who later sold the satellites to PrimeStar in the process of going out of business. PrimeStar's other satellite, Tempo 2 (later DirecTV-6) was launched in 1997, while Tempo 1 was stored until the company and both satellites were purchased by DirecTV. DirecTV eventually launched the Tempo 1 satellite after years of delays as the DirecTV-5 satellite in 2002.Currently, DirecTV-5 is located at 109.8°W and provides channels for the Puerto Rico market.Downtempo
Downtempo (sometimes used synonymously with "trip hop") is a genre of electronic music similar to ambient music, but with a greater emphasis on beats and a less "earthy" sound than trip hop.Ford Tempo
The Ford Tempo and its twin, the Mercury Topaz, are compact cars that were produced by Ford for model years 1984 to 1994. They were downsized successors to the boxy Ford Fairmont and Mercury Zephyr twins. The Tempo and Topaz were part of a rejuvenation plan by Ford to offer more environmentally friendly, fuel efficient, and more modern styled models to compete with the European and Japanese imports. While the car sold well, its innovation and aerodynamic design paved the way for the even more groundbreaking Ford Taurus. The Tempo and Topaz were replaced for 1995 by the "world car" platform sold in North America as the Ford Contour and Mercury Mystique.
Although built on a different platform, the aerodynamic Ford Sierra was somewhat of a European counterpart to the Tempo. It replaced the boxy, rear-wheel-drive Ford Cortina while the Tempo did the same for the Fairmont in North America. The Sierra too was succeeded by Ford's world car platform in the form of the Ford Mondeo.Glossary of musical terminology
This is a list of musical terms that are likely to be encountered in printed scores, music reviews, and program notes. Most of the terms are Italian (see also Italian musical terms used in English), in accordance with the Italian origins of many European musical conventions. Sometimes, the special musical meanings of these phrases differ from the original or current Italian meanings. Most of the other terms are taken from French and German, indicated by "Fr." and "Ger.", respectively.
Unless specified, the terms are Italian or English. The list can never be complete: some terms are common, and others are used only occasionally, and new ones are coined from time to time. Some composers prefer terms from their own language rather than the standard terms listed here.Groove metal
Groove metal (also known as post-thrash or neo-thrash) is a subgenre of heavy metal music. Music journalists and fans have used groove metal to describe Pantera, Exhorder and Machine Head. At its core, groove metal takes the intensity and sonic qualities of thrash metal and plays them at mid-tempo, with most bands making only occasional forays into fast tempo.Hi-NRG
Hi-NRG (pronounced "high energy") is a genre of uptempo disco that originated in the United States during the late 1970s and early 1980s.
As a music genre, typified by a fast tempo, staccato hi-hat rhythms (and the four-on-the-floor pattern), reverberated "intense" vocals and "pulsating" octave basslines, it was particularly influential on the disco scene. Its earliest association was with Italo disco.Minuet
A minuet (; also spelled menuet) is a social dance of French origin for two people, usually in 34 time. The word was adapted from Italian minuetto and French menuet, possibly from the French menu meaning slender, small, referring to the very small steps, or from the early 17th-century popular group dances called branle à mener or amener.
The term also describes the musical form that accompanies the dance, which subsequently developed more fully, often with a longer musical form called the minuet and trio, and was much used as a movement in the early classical symphony.Nike, Inc.
Nike, Inc. () is an American multinational corporation that is engaged in the design, development, manufacturing, and worldwide marketing and sales of footwear, apparel, equipment, accessories, and services. The company is headquartered near Beaverton, Oregon, in the Portland metropolitan area. It is the world's largest supplier of athletic shoes and apparel and a major manufacturer of sports equipment, with revenue in excess of US$24.1 billion in its fiscal year 2012 (ending May 31, 2012). As of 2012, it employed more than 44,000 people worldwide. In 2014 the brand alone was valued at $19 billion, making it the most valuable brand among sports businesses. As of 2017, the Nike brand is valued at $29.6 billion. Nike ranked No. 89 in the 2018 Fortune 500 list of the largest United States corporations by total revenue.The company was founded on January 25, 1964, as Blue Ribbon Sports, by Bill Bowerman and Phil Knight, and officially became Nike, Inc. on May 30, 1971. The company takes its name from Nike, the Greek goddess of victory. Nike markets its products under its own brand, as well as Nike Golf, Nike Pro, Nike+, Air Jordan, Nike Blazers, Air Force 1, Nike Dunk, Air Max, Foamposite, Nike Skateboarding, Nike CR7, and subsidiaries including Brand Jordan, Hurley International and Converse. Nike also owned Bauer Hockey (later renamed Nike Bauer) from 1995 to 2008, and previously owned Cole Haan and Umbro. In addition to manufacturing sportswear and equipment, the company operates retail stores under the Niketown name. Nike sponsors many high-profile athletes and sports teams around the world, with the highly recognized trademarks of "Just Do It" and the Swoosh logo.Passa Tempo
Passa Tempo is a municipality in the state of Minas Gerais in the Southeast region of Brazil.Rhythm
Rhythm (from Greek ῥυθμός, rhythmos, "any regular recurring motion, symmetry" (Liddell and Scott 1996)) generally means a "movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions" (Anon. 1971, 2537). This general meaning of regular recurrence or pattern in time can apply to a wide variety of cyclical natural phenomena having a periodicity or frequency of anything from microseconds to several seconds (as with the riff in a rock music song); to several minutes or hours, or, at the most extreme, even over many years.
In the performance arts, rhythm is the timing of events on a human scale; of musical sounds and silences that occur over time, of the steps of a dance, or the meter of spoken language and poetry. In some performing arts, such as hip hop music, the rhythmic delivery of the lyrics is one of the most important elements of the style. Rhythm may also refer to visual presentation, as "timed movement through space" (Jirousek 1995) and a common language of pattern unites rhythm with geometry. In recent years, rhythm and meter have become an important area of research among music scholars. Recent work in these areas includes books by Maury Yeston (1976), Fred Lerdahl and Ray Jackendoff (Lerdahl and Jackendoff 1983), Jonathan Kramer, Christopher Hasty (1997), Godfried Toussaint (2005), William Rothstein (1989), Joel Lester (Lester 1986), and Guerino Mazzola.Tempo (Indonesian magazine)
Tempo is an Indonesian weekly magazine that covers news and politics. It was founded by Goenawan Mohamad and Yusril Djalinus and the first edition was published on 6 March 1971.Tempo (bridge)
In the card game of bridge, tempo refers to the timing advantage of being on lead, thus being first to initiate one's play strategy to develop tricks for one's side. Tempo also refers to the speed of play and more generally refers to the rhythm of play over several tricks.
According to the rules of the game, the right to select the first card to play (the opening lead) belongs to the defenders; afterwards, the right to lead belongs to the hand who has won the previous trick. Being on lead generally presents an advantage, as it presents an opportunity to choose a suit and card which will develop a trick for the leader's side. However, in endplay situations being on lead certainly does not present an advantage—quite the opposite.
The tempo can be used for many purposes:
Setting up tricks – for example, against notrump contracts, defenders will often lead the longest and strongest suit, to set up the tricks in that suit. Against trump contracts, lead of a short suit can set up a subsequent ruff before the declarer can draw trumps.
Pitching losers – for example, having x opposite AKQx, the declarer may discard cards from another suit on the honors, holding xxx opposite xxx if on lead; if the opponents were on lead, they can cash the tricks in the declarer's weak suit.
Taking tricks – the converse of pitching losers. Having the lead lets us take our tricks before the other side gets to pitch in the suit(s).
Trump promotion or coup en passant – if the other side had the lead, they could simply draw trumps; however, with our side on lead, an extra trump trick can be produced.
Killing entries – opponents can be forced to use entries in the wrong order.Tempo (chess)
In chess and other chess-like games, a tempo is a "turn" or single move. When a player achieves a desired result in one fewer move, the player is said to "gain a tempo"; conversely, when a player takes one more move than necessary, the player is said to "lose a tempo". Similarly, when a player forces their opponent to make moves not according to their initial plan, one is said to "gain tempo" because the opponent is wasting moves. A move that gains a tempo is often called "a move with tempo".
A simple example of losing a tempo may be moving a rook from the h1-square to h5 and from there to h8 in the first diagram; simply moving from h1 to h8 would have achieved the same result with a tempo to spare. However, such maneuvers do not always lose a tempo—the rook on h5 may make some threat which needs to be responded to. In this case, since both players have "lost" a tempo, the net result in terms of time is nil, but the change brought about in the position may favor one player more than the other.Tempo Networks
Tempo Networks is a pan-Caribbean television channel broadcasting the music and culture of the Caribbean. Programming includes music videos, news, dramas, and documentaries addressing all aspects of Caribbean life. Musical genres broadcast include Reggae, Soca, Dancehall, Ska, Calypso, Chutney, Chutney Soca, Reggaeton, and Punta rock. Although programming is largely in English, TEMPO seeks to bring together the English, Spanish, French, and Dutch cultures of the Caribbean into one united Caribbean.
It launched on November 30, 2005 under the ownership of MTV Networks and corporate parent Viacom. Since 2007, it has been owned by founder Frederick Morton, Jr., and is based in Newark, NJ.The station broadcasts on Cablevision in the New York Metropolitan Area (Channel 1105), and reaches over 3,500,000 viewers in the Caribbean. It streams live over the internet 24 hours a day.Tempo and Mode in Evolution
Tempo and Mode in Evolution (1944) was George Gaylord Simpson's seminal contribution to the evolutionary synthesis, which integrated the facts of paleontology with those of genetics and natural selection.
Simpson argued that the microevolution of population genetics was sufficient in itself to explain the patterns of macroevolution observed by paleontology. Simpson also highlighted the distinction between tempo and mode. "Tempo" encompasses "evolutionary rates … their acceleration and deceleration, the conditions of exceptionally slow or rapid evolutions, and phenomena suggestive of inertia and momentum," while "mode" embraces "the study of the way, manner, or pattern of evolution, a study in which tempo is a basic factor, but which embraces considerably more than tempo."
Simpson's Tempo and Mode attempted to draw out several distinct generalizations:
Evolution's tempo can impart information about its mode.
Multiple tempos can be found in the fossil record: horotelic (medium tempo), bradytelic (slow tempo), and tachytelic (rapid tempo).
The facts of paleontology are consistent with the genetical theory of natural selection. Moreover, theories such as orthogenesis, Lamarckism, mutation pressures, and macromutations either are false or play little to no role.
Most evolution—"nine-tenths"—occurs by the steady phyletic transformation of whole lineages (anagenesis). This contrasts with Ernst Mayr's interpretation of speciation by splitting, particularly allopatric and peripatric speciation.
The lack of evidence for evolutionary transitions in the fossil record is best accounted for, first, by the poorness of the geological record, and, second, as a consequence of quantum evolution (which is responsible for "the origin of taxonomic units of relatively high rank, such as families, orders, and classes"). Quantum evolution built upon Sewall Wright's theory of random genetic drift.Tempo and Mode earned Simpson the Daniel Giraud Elliot Medal from the National Academy of Sciences in 1944. Fifty years after its publication, the National Academy of Sciences commissioned a book entitled Tempo and Mode in Evolution: Genetics and Paleontology 50 Years After Simpson edited by Walter M. Fitch and Francisco J. Ayala. It includes contributions by Ayala, Stephen Jay Gould, and W. Ford Doolittle.