20 April 2011

The Intellectual History of the Court Jester Hypothesis in Evolution

Where did the term "the Court Jester Hypothesis" in evolutionary theory come from?

The "Court Jester hypothesis" terminology is a reaction and intended counterpart to the Red Queen hypothesis in evolutionary theory.

The Red Queen hypothesis is a term coined by Leigh Van Valen in 1973 in a reference to the Lewis Carroll book "Through the Looking Glass," and refers in evolution theory to the arms race of evolutionary developments and counter-developments that cause co-evolving species to mutually drive each other to adapt.  There is dispute over how strongly evolution at the scale of speciation is driven by these competition between species, and how much it is driven instead by abiotic factors like meteor strikes and climate change.  But, there has been an artful metaphor to capture this distinction until recently.  As recently as 1985, the main alternative to the Red Queen hypothesis was called the "stability hypothesis" (coined by Stenseth and Maynard Smith in 1984).

These days, however, a number of researchers in evolution (such as Anthony Barnowsky, M.J. Benton, Thomas Ezard, Sergey Gravilets, and the team of J.B.C. Jackson and Douglas Erwin) have started to advance the term "Court Jester hypothesis" to describe the view that evolution at a macro scale is driven by abiotic factors more than the biotic competition called the Red Queen hypothesis.

The first reference that I can find in the literature to the "Court Jester" hypothesis, a term specifically coined in reference to the Red Queen hypothesis is in Anthony D. Barnosky, "Does evolution dance to the Red Queen or the Court Jester?", 3 Annual Meeting of the Society of Vertebrate Paleontology USA (1999). In a 2001 paper on the subject ("Distinguishing The Effects Of The Red Queen And Court Jester On Miocene Mammal Evolution In The Northern Rocky Mountains"), Barnosky uses the term without citation, suggesting that he is the one who coined it. Westfall and Millar attribute the term to him (citing the 2001 paper) in a paper of their own from 2004.  Benton also credits Barnosky with coining the phrase in a 2010 paper on the origins of biodiversity on land.

The Court Jester hypothesis builds upon the punctuated equalibrium theory of Gould (1972) by providing a primary mechanism for it. Table 1 in the 2001 paper by Barnosky appropriates for the Court Jester side of the debate the Stability hypothesis, Vrba's Habitat Theory (1992), Vrba's Turn-over pulse hypothesis (1985), Vrba's Traffic light hypothesis and Relay Model (1995), Gould's Tiers of Time (1985), Brett and Baird's Coordinated Statis (1995), and Graham and Lundelius' Coevolutionary Disequalibrium (184) theories. Give the profoundly not catchy quality of these earlier theories, it isn't hard to understand why the term "the Court Jester hypothesis" has had more staying power in the literature.

The 2001 paper, alas, does not spell out the metaphor underlying the "Court Jester" terminology and the 1999 presentation that apparently introduced the metaphor isn't easily available on line in full text. In the 2001 paper Barnosky states that the debate is over:

[W]hether this march of morphology and species compositions through time, so well documented not only for mammals but throughout the fossil record, is more strongly influenced by interactions among species (Red Queen hypotheses), or by random perturbations to the physical environment such as climate change, tectonic events, or even bolide impacts that change the ground rules for the biota (Court Jester hypotheses). . . . A class of alternative ideas, here termed Court Jester hypotheses, share the basic tenet that changes in the physical environment rather than biotic interactions themselves are the initiators of major changes in organisms and ecosystems. Some of the more prominent ideas are listed in Table 1. Court Jester hypotheses imply that events random in respect to the biota occasionally change the rules on the biotic playing field. Accelerated biotic response (relative to background rates) is the result.

Despite the fact that the Court Jester metaphor is coined in reference to the Red Queen hypothesis, the Jester reference, metaphorically, is not a direct reference to Through The Looking Glass, the Lewis Carroll book from which the Red Queen metaphor is derived, or the other Lewis Carroll book about Alice, Alice in Wonderland. There is no Court Jester in either book.

The best metaphorical sense I can find for the term is that it plays on the notion of both a Queen and a Jester being part of a royal court, and that is uses the term, "Court Jester" in the sense of its meaning in the Tarot, where the Court Jester is the symbol of death triumphing over all:

In Tarot, "The Fool" is the first card of the Major Arcana. The tarot depiction of the Fool includes a man (or less often, a woman) juggling unconcernedly or otherwise distracted, with a dog (sometimes cat) at his heels. The fool is in the act of unknowingly walking off the edge of a cliff, precipice or other high place. Another Tarot character is Death. In the Middle Ages, Death is often shown in Jester's garb because "The last laugh is reserved for death." Also, Death humbles everyone just as jesters make fun of everyone regardless of standing.
Alternately, the Court Jester terminology may be a metaphorical reference to the Joker card in a deck of cards that can upset the settled order, or alternatively a reference to the related notion that a Court Jester is a disinterested player that has no stake or interests in the impact of his actions on any of the competing parties (since this theory posits a natural, abiotic cause). As Wikipedia explains:

The position of the Joker playing card, as a wild card which has no fixed place in the hierarchy of King, Queen, Knave, etc. might be a remnant of the position of the court jester. This lack of any place in the hierarchy meant Kings could trust the counsel of the jesters, as they had no vested interest in any region, estate or church.
Barnowsky acknowledges in the 2001 paper that the Court Jester hypothesis is not necessary inconsistent with the Red Queen hypothesis: "Indeed, as Ned Johnson remarked (after listening to a lecture expressing these ideas), ‘‘Maybe it is time for the Court Jester to marry the Red Queen.’’ That is, perhaps the dichotomy between the two hypotheses is really a dichotomy of scale, and that as we look for ways to travel across biological levels, we will find ways to resolve the dichotomies."

Footnote: Other Notable Evolutionary Theory Names

Not wanting to miss out on the fun, Bradshaw and Brook in 2009 dubbed a similar notion the "Chronus hypothesis" in opposition to the existing Gaia hypothesis, coined by James Lovelock in 1965 (personifying the collective biosphere of Earth as a single being named after the Greek "mother earth"), which more or less corresponds to the "stability hypothesis" of macroevolution, as it sees the Earth's ecosystem as fundamentally stable, while also acknowledging the similar previously advanced "Media hypothesis" of Peter Ward which argues that life itself carries a self-destructive seed within it that sooner or later manifests catastrophically. The Chronus hypothesis article lays out those metaphors:

Cronus (Κρόνος) was the patricidal (or patri-emasculating) youngest son of Gaia, the Earth mother. Cronus was also the leader of the first generation of Titans, the giant descendants of Gaia and Uranus, the sky father. Cronus was incited by his mother to kill Uranus for perceived crimes against Gaia's other descendants, and Cronus himself was overthrown by his own son, Zeus, and banished to Hades (Atsma 2009). Given the tumultuous and competitive life-and-death history of Cronus, we believe this metaphor better captures the processes of inter-species competition and mutualisms that our population analogy of speciation and extinction embodies. Under the Gaia model, self-regulation works to avoid extinction because it is akin to the loss of a body part (function is reduced), whereas under Cronus, extinction is part of the process of natural selection (providing restoration of function through subsequent diversification). . . .

[T]he sorceress Medea (Μήδεια) was the granddaughter of Helios the sun god and wife to Jason of the Argonauts who later killed her own sons as revenge for Jason's unfaithfulness (Atsma 2009). Instead of the self-regulating super-organism Gaia, Ward describes the Earth's mass extinctions as Medean events – large biodiversity loss driven by life itself (Ward 2009a). Arguing that the Gaia hypothesis cannot account for large shifts in the Earth's temperature over geological time, Medea describes how the massive flux of atmospheric carbon dioxide and methane by the processes of plant, microbial and animal respiration was the very cause of such volatile conditions which lead to (at least some) mass extinctions (Ward 2009a,b). In essence, the Medean perspective describes a self-destructive, or anti-order component where life "seeks" to destroy itself, and it can do so on a massive scale due to amplifying feedbacks under certain circumstances (Ward 2009a,b). Modern human society might eventually merit the Medean soubriquet.
(This post was originally a comment at Razib's blog who alerted me to the existence of the term.)

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