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JEHOVAH Continues to school his would be correctors

 Is the Panda’s Thumb Suboptimal?

Stephen Dilley

In a classic argument, Stephen Jay Gould claimed that the panda’s thumb was suboptimal and, thus, counted as evidence in favor of evolution over special creation. In the contemporary era, this argument has become something of an icon as well as a broader symbol of the apparent problem of suboptimality in nature.1 If nature is the product of an intelligent designer, why are some biological phenomena so poorly made? In a recent peer-reviewed essay in the journal Religions, I revisited Gould’s argument as a way into this question and others like it.2 In a series of five posts here, of which this is the first, I will analyze the subject in some detail.

Here is the abstract of my article for Religions:

The panda’s thumb argument, championed by the late Stephen Jay Gould, stands as one of the most famous polemics for common ancestry. In this essay, I analyze Gould’s argument in several steps. First, I attempt to reconstruct the argument in both deductive and likelihood formulations. I contend that both versions of the argument rest on a theological claim — roughly, that God would not (likely) create or allow a suboptimal panda’s thumb. I then argue that a wide range of people are not rationally obligated to accept this theological claim. Next, I give special attention to the likelihood formulation’s emphasis on a contrastive argument for evolution over special creation. I contend that a great number of people are not rationally obligated to accept this formulation either. I next consider and reply to an objection that Gould never intended the panda argument as an apologetic for evolution (and an attack on special creation) but rather as a critique of adaptationism. Finally, I argue that the panda argument conflicts with Gould’s broader views about the human mind and the relationship between theology and science. I also note along the way that the shortcomings of the panda argument apply to a number of other arguments for evolutionary theory. To be sure, I do not criticize evolution itself or the comprehensive grounds for it. Instead, my primary aims are to analyze the panda argument and suggest that caution is in order about similar arguments as well.

Let’s first consider the crucial empirical question of whether the panda’s thumb is indeed suboptimal. Is it “clumsy” and “highly inefficient,” as Gould claims it to be? Or does it perform its function just fine? In subsequent posts, I will analyze more philosophical questions and topics: Is the panda argument a problem for intelligent design scientists? And is the panda argument a problem for evolutionists? 

Clumsy, Clumsy, Clumsy

As to the question of suboptimality, the answer centers on the thumb’s function. Gould thinks it does its job in a mediocre way. He notes that Darwin thought much the same about orchids. Gould explains:

The panda’s thumb provides an elegant zoological counterpart to Darwin’s orchids. An engineer’s best solution is debarred by history. The panda’s thumb is committed to another role, too specialized for a different function to become an opposable, manipulating digit. So the panda must use parts on hand and settle for an enlarged wrist bone and a somewhat clumsy, but quite workable solution. The sesamoid thumb wins no prize in an engineer’s derby.3

He also explains:

The panda’s “thumb” demonstrates evolution because it is clumsy and built from an odd part, the radial sesamoid bone of the wrist. The true thumb had been so shaped in its ancestral role as the running and clawing digit of a carnivore that it could not be modified into an opposable grasper for bamboo in a vegetarian descendant.4

At the heart of Gould’s argument is the claim that the panda’s thumb is “clumsy” or, as he says elsewhere, “highly inefficient.”5

Gould explains that suboptimality favors evolution whereas “ideal design” favors special creation.

[I]deal design is a lousy argument for evolution, for it mimics the postulated action of an omnipotent creator. Odd arrangements and funny solutions are the proof of evolution — paths that a sensible God would never tread but that a natural process, constrained by history, follows perforce.6

The basic argument is that “[o]dd arrangements and funny solutions” point to evolution whereas “ideal design” points to a “sensible God.” Given that the panda’s thumb “wins no prize in an engineer’s derby,” it supports evolution rather than divine design.

The Empirical Evidence

Yet the scientific data say otherwise. As I explain in the article:

Oddly, Gould does not give strong reasons to accept this claim [that the panda’s thumb is suboptimal]; nowhere in his writings does he provide a detailed empirical study that demonstrates the suboptimality of the panda’s thumb. The major research that Gould relies upon, Dwight Davis’s study, used a dead panda for its conclusions about comparative morphology; it did not examine how effective living pandas are at stripping bamboo leaves. Biologist John Gittleman notes that the analyses of both Davis and Gould arose “despite any real information on how the giant panda lives in nature.”7

Two major studies gave high praise to the function and efficiency of the panda’s thumb:

The first major study of living pandas — focusing specifically on their adaptation to bamboo — was conducted by George Schaller’s team, which published its results in The Giant Pandas of Wolong. They observed that pandas “efficiently bring food to the mouth with their forepaws” and “handle bamboo stems with great precision by holding them as if with forceps in the hairless groove connecting the pad of the first digit and pseudothumb.”8

Schaller and his team reported:

When watching a panda eat leaves, stem or new shoots we were always impressed by its dexterity. Forepaws and mouth work together with great precision, with great economy of motion, as the food is grasped, plucked, peeled, stripped, bitten and otherwise prepared for being swallowed. Actions are fluid and rapid…9

Similarly, in 1999, a team of Japanese scientists conducted perhaps the most sophisticated analysis of the panda’s thumb to date. They used “computed topography, magnetic resonance imaging, and live observation to analyze the structure and function of the panda’s thumb.” They reported that the thumb 

and its accessories enable the panda to “manipulate objects with great dexterity.” In fact, the “way in which the giant panda, Ailuropoda melanoleuca, uses the radial sesamoid bone — its ‘pseudo-thumb’ — for grasping makes it one of the most extraordinary manipulation systems in mammalian evolution.” They conclude that “the hand of the giant panda has a much more refined grasping mechanism than has been suggested in previous morphological models,” including Davis’s model.10

Turning the Tables

Gould’s claim is mistaken. The panda’s thumb is not suboptimal. The best studies we have conclude that the thumb is anything but “clumsy” or “highly inefficient.” Instead, they describe it as having “great precision,” “great economy of motion,” and “great dexterity.” It may even rank as “one of the most extraordinary manipulation systems” among mammals. That is quite an accolade.

Indeed, one might rather regard the thumb as positive evidence for intelligent design. A system of such precision, efficiency, economy, and dexterity is a spectacle of a high order. That sounds very much like the kind of sophistication that only engineers produce. 

On this score, recall the way Gould himself framed the panda argument: “[o]dd arrangements and funny solutions” point to evolution whereas “ideal design” points to a “sensible God.”11 So, by this logic, the panda’s thumb appears to count as stronger evidence in favor of design. Perhaps it’s time to champion the panda’s thumb not as an icon for evolution but for intelligent design

Notes

See Dilley, “God, Gould, and the Panda’s Thumb,” p. 1.

Stephen Dilley. 2023. “God, Gould, and the Panda’s Thumb.” Religions 14: 1006. https://doi.org/ 10.3390/rel14081006.

Stephen Jay Gould. 1980. The Panda’s Thumb. New York: W.W. Norton, p. 24.

Gould, The Panda’s Thumb, p. 29, original emphasis.

Stephen Jay Gould. 1986. “Evolution and the Triumph of Homology, Or Why History Matters.” American Scientist 74: 60-69, esp. p. 63.

Gould, The Panda’s Thumb, p. 20-21.

Dilley, “God, Gould, and the Panda’s Thumb,” p. 11. For the Gittleman quote, see John L. Gittleman. 1985. “Review of The Giant Pandas of Wolong.” The Quarterly Review of Biology 60: 524. 

Dilley, “God, Gould, and the Panda’s Thumb,” p. 11. For the Schaller quote, see George B. Schaller, Hu Jinchu, Pan Wenshi, and Zhu Jing. 1985. The Giant Pandas of Wolong. Chicago: University of Chicago Press, p. 4, 215.

Schaller et al., The Giant Pandas of Wolong, p. 58.

Dilley, “God, Gould, and the Panda’s Thumb,” p. 11. See also Hideki Endo, Daishiro Yamagiwa, Yoshihiro Hayashi, Hiroshi Koie, Yoshiki Yamaya, and Junpei Kimura. 1999. “Role of the Giant Panda’s ‘Pseudo-thumb’.” Nature 397: 309-10.

Gould, The Panda’s Thumb, p. 20-21.