Doubting Altruism: New research casts a skeptical eye on the evolution of genuine altruism

originally posted on eSkeptic , Wednesday, January 28th, 2009

by Kenneth W. Krause

As we soar into an inspiring new era of genomics, genetic manipulation, and, potentially, the directed evolution of our own species, naturalists urge us to remain partially grounded — to keep digging for long-buried evidence of key pre-historical developments. In so doing, however, the world’s leading anthropologists and primatologists have immersed themselves in a now-roiling debate over the origins of human morality in general and altruism in particular.

Some say that altruism — sometimes referred to as “other-regarding preferences” or “unsolicited prosociality” — is nothing more than a veneer, a cultural innovation humans alone have achieved in order to collectively restrain each individual’s natural proclivity to serve only herself, her close genetic relatives, and those who have demonstrated an adequate inclination to reciprocate to her eventual benefit. For these folks, no act can be characterized as wholly unselfish.

Others argue that altruism is more primitive than culture and, in fact, considerably more ancient than the human species itself. Other-regarding preferences, they say, are deeply innate, predating even the phylogenetic split that occurred six million years ago among the common ancestors of chimps and bonobos on the one hand and all species of hominid on the other. According to this camp’s credo, selflessness is as natural as appetite.

One line of experiments has confronted the issue directly, inquiring whether non-human primates will seize opportunities to assist others. In 2005, for example, UCLA anthropologist Joan Silk and others chose 18 chimpanzees (Pan troglodytes) as the subjects of two such experiments, conducted in Louisiana and Texas.¹ Chimps are among the primates most likely to exhibit unsolicited prosocial behavior, they reasoned, because in the wild they regularly hunt, patrol, and mate-guard cooperatively.

In each study, subject chimps were allowed to deliver food to other chimps, or “conspecifics,” at no cost to themselves. The test apparatuses provided each confined subject with two options — the 1/0 choice where it could acquire food only for itself, and the 1/1 choice where it could obtain food for both itself and its separately caged partner. As an essential control, acting chimps were given the same options with no partners present (Figure 1).

Figure 1. A test apparatus providing a subject with two options: acquire food only for itself (1/0), or obtain food for both itself and its separately caged partner (1/1).

Silk’s team predicted that if chimps are truly altruistic they should choose the 1/1 option more often than the 1/0 option when a conspecific is there to benefit. But that wasn’t the case. In Louisiana, not one of the seven subjects chose the 1/1 option significantly more often when partnered. In Texas, the remaining 11 actors went with both the 1/1 and the 1/0 option an average of only 48 percent of the time when another chimp was present.

“The absence of other-regarding preferences in chimpanzees,” the authors inferred, “may indicate that such preferences are a derived property of the human species tied to sophisticated capacities for cultural learning, theory of mind, perspective taking and moral judgment.” Nevertheless, Silk’s team remained open to the prospect that altruism might be detected among primates that, in some crucial ways, were even more cooperative than chimps. We will consider that possibility later.

Altruism’s Alter-Ego

A closely related line of experiments has tackled the same issue from a different direction, asking instead whether primates display a rudimentary sense of fairness in some form of “inequity aversion” (IA). If an animal reacts negatively to its own relative overcompensation, we say it has demonstrated some sensitivity to “advantageous inequity.” If it merely responds to a conspecific’s superior gain, on the other hand, the animal has shown aversion only to “disadvantageous inequity.”

The former inclination probably evolved after (and, morally speaking, is emphatically more advanced than) the latter because an animal sensitive to its own advantage can demonstrate not only an egocentric expectation of how it should be treated, but also a communal expectation of how all members of its species should be treated. In either case, if test subjects attempt to restore equity by sacrificing their own gains — even if only to simultaneously and unceremoniously deny superior gains to their luckier partners — according to many (but not all) researchers, they have nonetheless acted altruistically.

In 2003, Emory University primatologists Sarah Brosnan and Frans de Waal developed token exchange experiments where tufted capuchin monkeys (Cebus apella) were measured for their reactions to situations in which their partners received greater food rewards.² In the end, shortchanged subjects proved less likely to complete exchanges for identical tokens, and withdrew even more frequently when their partners received prizes for no tokens at all. These now-classic results have been widely interpreted as formidable evidence of disadvantageous IA in primates.

Two years later, Brosnan, de Waal, and Hillary Schiff released the outcomes of a similar study of adult chimpanzees.³ In order to distinguish the effects of social alignment, the team chose four animals that had lived continuously in pairs and 16 others that had been housed together at the Yerkes National Primate Research Center in Atlanta, Georgia for either 30 years or eight years prior to testing. As in the 2003 experiment, subjects were given tokens — in this case, rather useless and nondescript chunks of white PVC pipe — which they had been trained to return for either cucumber slices (the low-value reward) or grapes (the high-value reward).

During the inequity test, examiners initially allowed the partner chimps to exchange for a juicy, delicious grape — while eager subjects observed, of course — and then offered the subjects a relatively dry and no doubt disappointing cucumber slice. The examiners diligently recorded the subjects’ reactions, noting whether they had accepted or rejected their prizes. Brosnan discovered first that, when the tables were turned, subjects did not react negatively when given a superior reward and, thus, were likely not averse to advantageous inequity. Whether such a finding actually distinguished chimpanzees from humans in any meaningful way, the authors noted, was questionable.

Second, according to Brosnan, the results confirmed that disadvantageous IA was “present and robust” among chimpanzees, although to significantly different degrees depending on each subject’s social history. Chimps that had lived in pairs or in relatively novel groups reacted most intensely, while animals from older, more tightly-integrated groups appeared more accepting of inequity — all of which could be entirely consistent with human predilections to either “make waves” or “go with the flow,” depending primarily on their social milieu. Tolerance of inequity, Brosnan suggested, may be more a function of group size and intimacy than either moral choice or any isolated cognitive factor. So by the end of 2005, very little if anything had been truly settled. The experiments would continue and become ever more creative and exacting, but the already muddied anthropological waters would grow more cluttered and murkier still.

High Expectations

In 2006, three teams from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany published studies that in one way or another challenged these landmark outcomes from Yerkes. Julian Brauer’s group tested for IA among chimps, bonobos, gorillas, and orangutans — 30 individual great apes in all — and produced a pattern of food rejection that was opposite to that reported by Brosnan.⁴ In other words, instead of snubbing more food after seeing their partners receive tastier treats, Brauer’s apes actually rejected less food.

All the same, the authors did not infer that apes were necessarily insensitive to unfairness. In fact, at one point they questioned whether food refusal was a fair test of IA to begin with. Inequity-wary apes, after all, might decide to accept lower-quality spoils simply in an effort to offset the higher-quality gifts bestowed upon their partners. Citing a then-recently published study questioning chimpanzee altruism, however, Brauer’s team finally betrayed a clear inclination to attribute their results to the so-called “food expectation hypothesis,” which asserts that the mere act of witnessing a conspecific’s receipt of superior food will create an anticipation of acquiring the same food for oneself. Such an expectation might explain why Brauer’s chimps begged more vigorously and why many of her apes generally remained at their testing stations much longer after having witnessed partner overcompensation.

The study Brauer cited had been conducted by a second German team led by Keith Jensen.⁵ The key problem with Brosnan’s examination, according to Jensen, was that subject chimps were never allowed to convey their mind-sets by actually correcting unequal outcomes. Silk’s group had devised a somewhat more effective experiment in this respect, the authors commended, but even they had failed to test for anything more than selfishness (the 1/0 option) or mutualism (the 1/1 option). In Jensen’s experiments, by comparison, 11 chimps participated in three separate studies collectively designed to reveal expressed tendencies toward altruism and spite as well.

In study one, each subject was allowed to pull one of two tables toward itself. The first table contained bananas accessible to both the subject and its partner; the second table held fruit accessible only to the subject. Either way, subjects received the same reward. But because Jensen’s chimps predominantly chose the mutually accessible table in both the test (partner present) and control (partner absent) conditions, the results were inconclusive as to selfishness and mutualism. Nevertheless, Jensen vied, this initial phase of the experiment did show that his chimps were not averse to disadvantageous inequity, at least with regard to relative effort expended.

Studies two and three tested for spite and altruism. In neither case could any subject receive a reward for pulling any table closer to itself or its partner. In experiment two, acting chimps could have conveyed an other-regarding preference by pulling tables accessible only to partners, or passive spite by doing nothing at all more frequently in the test condition than in the control condition. But they did neither.

In experiment three, the scheme was altered slightly such that, in order to deny food to their partners, subjects needed to actively draw those partners’ trays away. But, once again, the Leipzig chimps were as likely to do nothing in one condition as in the other, thus failing to demonstrate active spite as well. The authors noted, however, that two of their six chimps did express potential signs of altruism. But these animals also tended to beg or harass their partners following delivery of the fruit, thus raising the possibility that they intended to only benefit themselves.

Food for Thought

Felix Warneken and Michael Tomasello, also from the Planck Institute, decided to examine the issue through an entirely different type of experiment. If altruism exists among our primate cousins, they judged, it might more readily be elicited with something less critical to individual survival than food. So Warneken and Tomasello tested both human children (24 18-month-old infants) and three young chimpanzees (34, 54, and 54 months old) for their willingness to help human caretakers (quite familiar to the chimps) with some task absent of any possible expectation of reward.⁶

As predicted, the children assisted experimenters more often and in a greater variety of tasks than the chimps. Nonetheless, each of Warneken’s chimps reliably helped a reaching human obtain apparently desired objects. Although young humans clearly cooperate to degrees found in no other species, the authors concluded, “our nearest primate relatives show some skills and motivations in this direction as well.”

By the summer of 2007, Warneken had assembled another team and published the results of similar “instrumental helping” experiments calculated to address several important and yet unanswered questions — in particular, whether 36 semi-free ranging chimps would spontaneously help unfamiliar humans and genetically unrelated conspecifics in addition to their caretakers, and whether they would do so at some significant cost to themselves.⁷

Again, as expected, infant children helped more quickly. But the chimps performed just as reliably regardless of their partners’ familiarity or species, even when they had to expend a little extra effort to do so. “The roots of human altruism may go deeper than previously thought,” Warneken ultimately concluded, “reaching as far back as the last common ancestor of humans and chimpanzees.”

Later that year, however, Keith Jensen’s team cast a skeptical eye on Warneken’s conclusions in two well-focused examinations of potential IA among chimps. The first pair of experiments probed 11 animals’ capacities for spite — altruism’s evil twin, if you will.⁸ Jensen reasoned that Chimps might be characterized as altruistic, at least in a punitive sense, if they choose to act out against conspecifics due to an abstract sense of fairness. In the first study, caged subjects were allowed to pull ropes to collapse food-laden tables drawn away by humans toward different enclosures that either contained other chimps (test condition) or were empty (control condition). In the end, the chimps appeared to be indifferent. Actors were just as likely to collapse the platforms when they approached empty cages as when they neared hungry conspecifics.

In the second study, subjects were exposed to three conditions. In conditions one and two, much as before, human experimenters pulled the tables away from subject animals and toward partners or empty cages. In the last condition, however, it was the partner chimps that were allowed to drag the tables away from subjects. Between the first two conditions there was no real disparity, indicating again that subjects didn’t really care whether their partners benefited inequitably. Between the first two and the third conditions, on the other hand, subjects were significantly more likely to drop the tables when other chimps, as opposed to humans, began drawing them away. From these combined results, Jensen concluded that although chimps are certainly vengeful, “[s]pitefulness may thus be a peculiarly human phenomenon.”

Ultimatums (and more Expectations)

Hailing it as the “benchmark test for examining sensitivity to fairness and other-regarding preferences,” Jensen then unleashed his 11 subjects on a chimp-friendly version of the celebrated ultimatum game.⁹ Proposer animals were permitted to make one of two possible offers to their receiving partners, potentially retaining either 100, 80, 50, or 20 percent of the spoils for themselves in each trial. If the receiver accepted the offer, each party got what it wanted. But if the receiver rejected the offer — having noted what the proposer intended to keep for itself — neither animal received any reward.

Presumably out of some concern for fairness, humans proposers tend to make equitable offers of 40 to 50 percent or, as receivers, to reject offers of 20 percent or less, thus confounding the economic model of rational self-interest (so-called Homo economicus). This was not how the Leipzig chimps reacted, however. Proposers chose not to make fair offers and receivers opted to accept all nonzero offers without hesitation or perceptible sign of irritation. While the authors cautioned that these outcomes “may be in part be a reflection of the fact that active food sharing is rare among the species,” they were clearly inclined to attribute such behaviors to the chimps’ absent sense of justice.

Figure 2. A monkey returns a token to the experimenter while using her left paw to steady the human hand. Her partner looks on. In this “hidden-reward exchange” the monkey does not see the reward she is to receive before successful exchange. (Redrawn from an illustration done from a video still by Gwen Bragg and Frans de Waal.¹⁰)

In late 2007, Megan van Wolkenten, working with Brosnan and de Waal, finally published a narrowly tailored response to Brauer and others addressing the alleged preeminence of food expectation over IA.10 They used the now-familiar token exchange experiment — this time enhanced with an additional condition where food rewards were shown to subjects well prior to exchange — on 13 capuchin monkeys (Figure 2). But, contrary to the predictions of various expectation hypotheses, behavioral changes did not depend on either greed or frustration. Rates of refusal among subjects, in fact, increased not when higher-value grapes were merely visible, but only when they were actually bestowed upon partners.

Importantly, van Wolkenten’s subjects also made significantly fewer exchanges when forced to expend more effort for the same lower-value cucumbers received by partners. As the food value increased, however, effort became secondary, indicating that capuchins are willing to reprove inequity only when the cost of doing so is slight. This appreciable yet limited brand of IA, the authors proposed, “likely evolved in conjunction with cooperative enterprises,” and “may characterize a great variety of social animals.”

More Monkey Business

By the end of 2007, then, the combined body of research had established mixed results at best, especially with regard to the great apes. Recalling Joan Silk’s suggestion that true altruism might be discovered among primates even more social than chimpanzees, Swiss anthropologist Judith Burkhart’s team decided to test 26 common marmoset monkeys (Callithrix jacchus) in two studies — one for related, one for unrelated pairs — involving hungry partners and subject-operated food trays (Figure 3).¹¹

Figure 3. The donor has the choice between two trays representing the payoff distributions (0,1) (upper tray with a cricket in the left food bowl) or (0,0) (lower tray). If the donor pulls the tray with the (0,1) payoff distribution, it results in a payoff to the recipient but none to itself. ¹¹

The experimenters provided each actor with a 0/0 option and a 0/1 option only, thus eliminating all potential for subject rewards. Because marmosets are cooperative breeding New-World monkeys, Burkhart predicted that if any primate should display an unsolicited prosocial tendency capable of overcoming any penchant for envy, it would be this species, despite their theory of mind deficit and general cognitive shortcomings.

Burkhart was right. Kin or no kin, marmoset subjects — fully schooled with the test apparatus and, thus, aware of the experiments’ consequences — pulled the 0/1 tray more often when their partners were present in adjacent cages than in the control condition when their partners were absent. Remarkably, the disparity widened significantly when female “helpers” — which, despite this distinction, tend not to carry other monkeys’ infants in the wild — were eliminated from the analysis. Because humans and New-World monkeys are the only primates that behave as cooperative caretakers, Burkhart proposed, strong altruism may have evolved within such groups independently, and not necessarily among the ancestors common to chimps, bonobos, and humans.

More Food for Thought

The thick, swirling waters of controversy have spilled largely unabated into 2008. Working with Brosnan, Silk, and others, American evolutionary psychologist Jennifer Vonk published a detailed study of low-cost, conspecific-directed altruism among 18 chimpanzees at the University of Louisianna’s Cognitive Evolution Group laboratory.¹² In two separate experiments involving two different apparatuses and two distinct groups of chimps, actors were given the options to trigger rewards for themselves alone, for their partners alone, or for both themselves and their partners.

The team chose these three options in order to address important criticisms of previous experiments involving food. Because her chimps were allowed to act prosocially only after having fed themselves, Vonk argued, this method avoided the possibility that subject animals might be distracted from an otherwise spirited altruistic tendency by the potent and ever-present need to feed.

If chimps are really other-regarding, the authors reasoned, subjects should deliver rewards to partner enclosures at some point during the experiment, but more often in the partner-present test condition than in the partner-absent control condition. By contrast, if chimps are indifferent to the welfare of others, actors should minimize their personal costs by obtaining rewards only for themselves. Ultimately, the presence of awaiting partners in other enclosures had no significant effect on subjects in either experiment. At first, actors consistently released both rewards. But delivery rates to other cages always decreased as subjects learned that such efforts would not benefit them.

Notably, one of the 11 chimps tested in the second experiment did choose to act prosocially, but these results could not be replicated. “[W]hile chimpanzees’ behavior is consistent with standard evolutionary models based on kinship and reciprocity,” Vonk insisted, “human cooperation and prosociality may require an emerging class of evolutionary models, rooted in the coevolutionary interaction of genes and culture.”

Agreeing to Disagree

Despite these equivocal results, some scientists still see altruism as a considerably more ancient impulse, born of the intense parental and, thus, empathic instinct. Frans de Waal, as one prominent example, appears to be thoroughly convinced that some skeptics of primate altruism have their arguments backwards — at least in one crucial respect. “[E]mpathy evolved in animals as the main proximate mechanism for [individually] directed altruism,” he explained in a recent review, and it is empathy — not self-interest — that “causes altruism to be dispensed in accordance with predictions from kin selection and reciprocal altruism theory.”¹³ Although gene propagation and benefit exchange may be the evolutionary or ultimate cause of altruism, only a spontaneous emotional response to another being’s situation can possibly trigger or proximately cause an altruistic impetus.

In his latest study of non-cooperatively breeding monkeys, de Waal discovered that brown capuchins will predominantly choose the 1/1 mutual option over the 1/0 selfish option, depending on the subjects’ familiarity with their partners.¹⁴ Although his monkeys’ other-regarding tendencies clearly turned on social closeness, de Waal nevertheless concluded that because kinship was critical and because his subjects had no means of predicting return favors, only empathy could explain this study’s results.

When I asked him about the persisting debate, de Waal proposed that the scientific community has become polarized between evolutionary biologists on the one side and, on the other, a discrete group of economists and anthropologists that “has invested heavily in the idea of strong reciprocity,” which absolutely demands discontinuity between humans and all other animals. As for the results obtained by Silk and others, de Waal offered, experiments such as these involving repeated trials and frequent rewards are vulnerable to “side-biases” that can skew outcomes.

Sarah Brosnan, a former student of de Waal’s and now Assistant Professor of Psychology at Georgia State University, remains ambivalent. Her subjective though surely copious experience with both apes and monkeys informs her that at least some of these animals do seem altruistic. Even so, she told me, “there is not too much evidence for this outside some of Frans’ and Felix Warneken’s work.” But cooperation in all species, she emphasized, “is much more likely to be based on emotion and relationships than on cognitive calculations.”

Both de Waal and colleague Keith Jensen are doubtful that even chimpanzees possess the cognitive capacities requisite for delayed reciprocation. But for Jensen, the added conclusion that chimps must be altruists simply doesn’t follow. “De Waal’s use of the term ‘empathy’ is somewhat contentious,” he told me, “and the evidence he provides for empathy is [anecdotal and] not very robust.”¹⁵ More evidence is needed, he admitted, but, like Jennifer Vonk, his “working hypothesis” is that other-regarding preferences emerged at some point during human evolution only.

Even so, both Brosnan and Jensen conceded that the distinction between food exchange and instrumental helping is a potentially crucial one. Indeed, Jensen and Felix Warneken are now collaborating on a new project to determine whether food rewards might interfere with genuine other-regarding preferences. Although “food exchange is not a bad test for altruism,” Warneken reminded me, it explores “only one type of potentially altruistic behavior.” In the more sensitive context of instrumental tasks, he added, chimpanzees have repeatedly demonstrated solid helping tendencies.

When I asked Warneken about Vonk’s latest attempt to neutralize the nutritional imperative, he warned that Vonk’s chimps might not have fully understood how the apparatuses worked during that experiment’s altruism phase. “The pattern of results,” he argued, “still suggests that the subjects had a tendency to try to obtain the reward for themselves.” Plugging Jensen’s 2006 study as the most convincing presentation to date of limited prosociality among chimps, Warneken recommended that future researchers follow that team’s lead, at least with respect to designing an apparatus that animals might comprehend more intuitively.

Where to Go from Here

Everyone agrees that more work needs to be done, and that no research could be more germane to achieving a competent grasp of who we are as a species and where we might be headed. If altruism is in fact deeply innate to humanity’s collective being, we may have to rethink a number of things, including some of our most established political and economic assumptions.¹⁶ Jensen summed it up pretty well when I invited him to characterize his work’s significance:

This research is interesting to the question of what makes humans special, if, indeed, they are. Most research in the past has focused on “cold cognition” such as abstract reasoning, language and tool use. Social motivations and emotions — “hot cognition” — are just as important, and may even be central to the emergence of human ultrasociality. Holding a lens up to ourselves after focusing it on other species will help us see ourselves more clearly.

So it looks like we’ll be hearing a great deal more from these and other esteemed authorities during the coming years. Sadly, however, the indispensable subjects of these investigations seem to be living on borrowed time, the African great apes especially. If scientists can ever clear the dim, shadowy depths of altruistic origins, they’ll have to act quickly before our own dark natures drive our ancestral cousins into extinction.

References

1. Silk, J. B., Brosnan, S. F., Vonk, J., Henrich, J., Povinelli, D. J., Richardson, A. S., Lambeth, S. P., Mascaro, J. & Shapiro, S. J. 2005. “Chimpanzees Are Indifferent to the Welfare of Unrelated Group Members.“ Nature, 437, 1357–1359.
2. Brosnan, S. F. & de Waal, F. B. M. 2003. “Monkeys Reject Unequal Pay.” Nature, 425, 297–299.
3. Brosnan, S. F., Schiff, H. C. & de Waal, F. B. M. 2005. “Tolerance for Inequity May Increase With Social Closeness In Chimpanzees.” Proc. R. Soc. B, 272, 253–258.
4. Brauer, J., Call, J. & Tomasello, M. 2006. “Are Apes Really Inequity Averse?” Proc. R. Soc. B, 273, 3123–3128.
5. Jensen, K., Hare, B., Call, J. & Tomasello, M. 2006. “What’s in it for me? Self-regard Precludes Altruism and Spite In Chimpanzees.” Proc. R. Soc. B, 273, 1013–1021.
6. Warneken, F. & Tomasello, M. 2006. “Altruistic Helping In Human Infants and Young Chimpanzees.” Science, 311, 1301–1303.
7. Warneken, F., Hare, B., Melis, A. P., Hanus, D. & Tomasello, M. 2007. “ Spontaneous Altruism By Chimpanzees and Young Children.” PloS Biology, 5(7), e184.
8. Jensen, K., Call, J. & Tomasello, M. 2007. “Chimpanzees Are Vengeful But Not Spiteful.” Proc. Natl. Acad. Sci., USA, 104, 13046–13050.
9. Jensen, K., Call, J. & Tomasello, M. 2007. “Chimpanzees are Rational Maximizers In an Ultimatum Game.” Science, 318, 107–109.
10. van Wolkenten, M., Brosnan, S. F. & de Waal, F. B. M. 2007. “Inequity Responses of Monkeys Modified by Effort.” Proc. Natl. Acad. Sci., USA, 104, 18854–18859.
11. Burkhart, J. M., Fehr, E., Efferson, C. & van Schaik, C. P. 2007. “ Other-Regarding Preferences In a Non-Human Primate: Common Marmosets Provision Food Altruistically.” Proc. Natl. Acad. Sci., 104, 19762–19766.
12. Vonk, J., Brosnan, S. F., Silk, J. B., Henrich, J., Richardson, A., Lambeth, S., Schapiro, S. & Povinelli, D. J. 2008. “Chimpanzees Do Not Take Advantage of Very Low Cost Opportunities to Deliver Food to Unrelated Group Members.” Animal Behavior, 75, 1757–1770.
13. de Waal, F. B. M. 2008. “Putting the Altruism Back Into Altruism: The Evolution of Empathy.” Annu. Rev. Psychol., 59, 279–300.
14. de Waal, F. B. M., Leimgruber, K. & Greenberg, A. R. 2008. “Giving Is Self-rewarding for Monkeys.” Proc. Natl. Acad. Sci., USA. 105, 13685–13689.
15. See also, Silk, J. B. 2007. “Empathy, Sympathy, and Prosocial Preferences In Primates.’ In: The Oxford Handbook of Evolutionary Psychology. (Ed. by R. I. M. Dunbar & L. Barrett), pp. 115–126. Oxford: Oxford University Press (“ Current claims for the existence of empathy, sympathy, moral sentiments, and other-regarding preferences in other primates rest on an insecure empirical foundation.”).
16. See, e.g., Bowles, S. 2008. “Policies Designed for Self-interested Citizens May Undermine ‘the Moral Sentiments’: Evidence from Economic Experiments.” Science, 320, 1605–1609 (“Economists, psychologists, and others … are well on their way to constructing an economic psychology of the interplay of self-regarding and other-regarding motivation that may eventually enlighten mechanism design and public policy.”).

Contributed by  R. Chavid

Nothing in Biology Makes Sense Except in the Light of Evolution

By Theodosius Dobzhansky, “Nothing in biology makes sense except in the light of evolution.” The American Biology Teacher, March 1973

“As recently as 1966, sheik Abd el Aziz bin Baz asked the king of Saudi Arabia to suppress a heresy that was spreading in his land. Wrote the sheik:

The Holy Koran, the Prophet’s teachings, the majority of Islamic scientists, and the actual facts all prove that the sun is running in its orbit… and that the earth is fixed and stable, spread out by God for his mankind…. Anyone who professed otherwise would utter a charge of falsehood toward God, the Koran, and the Prophet.

The good sheik evidently holds the Copernican theory to be a “mere theory,” not a “fact.” In this he is technically correct. A theory can be verified by a mass of facts, but it becomes a proven theory, not a fact. The sheik was perhaps unaware that the Space Age had begun before he asked the king to suppress the Copernican heresy. The sphericity of the earth has been seen by astronauts, and even by many earth-bound people on their television screens. Perhaps the sheik could retort that those who venture beyond the confines of God’s earth suffer hallucinations, and that the earth is really flat.

Parts of the Copernican world model, such as the contention that the earth rotates around the sun, and not vice versa, have not been verified by direct observations even to the extent the sphericity of the earth has been. Yet scientists accept the model as an accurate representation of reality. Why? Because it makes sense of a multitude of facts which are otherwise meaningless or extravagant. To non-specialists most of these facts are unfamiliar. Why then do we accept the “mere theory” that the earth is a sphere revolving around a spherical sun? Are we simply submitting to authority? Not quite: we know that those who took the time to study the evidence found it convincing.

The good sheik is probably ignorant of the evidence. Even more likely, he is so hopelessly biased that no amount of evidence would impress him. Anyway, it would be sheer waste of time to attempt to convince him. The Koran and the Bible do not contradict Copernicus, nor does Copernicus contradict them. It is ludicrous to mistake the Bible and the Koran for primers of natural science. They treat of matters even more important: the meaning of man and his relations to God. They are written in poetic symbols that were understandable to people of the age when they were written, as well as to peoples of all other ages. The king of Arabia did not comply with the sheik’s demand. He knew that some people fear enlightenment, because enlightenment threatens their vested interests. Education is not to be used to promote obscurantism.

The earth is not the geometric center of the universe, although it may be its spiritual center. It is a mere speck of dust in the cosmic spaces. Contrary to Bishop Ussher’s calculations, the world did not appear in approximately its present state in 4004 BC. The estimates of the age of the universe given by modern cosmologists are still only rough approximations, which are revised (usually upward) as the methods of estimation are refined. Some cosmologists take the universe to be about 10 billion years old; others suppose that it may have existed, and will continue to exist, eternally. The origin of life on earth is dated tentatively between 3 and 5 billion years ago; manlike beings appeared relatively quite recently, between 2 and 4 million years ago. The estimates of the age of the earth, of the duration of the geologic and paleontologic eras, and of the antiquity of man’s ancestors are now based mainly on radiometric evidence the proportions of isotopes of certain chemical elements in rocks suitable for such studies.

Shiek bin Baz and his like refuse to accept the radiometric evidence, because it is a “mere theory.” What is the alternative? One can suppose that the Creator saw fit to play deceitful tricks on geologists and biologists. He carefully arranged to have various rocks provided with isotope ratios just right to mislead us into thinking that certain rocks are 2 billion years old, others 2 million, which in fact they are only some 6,000 years old. This kind of pseudo-explanation is not very new. One of the early anti-evolutionists, P. H. Gosse, published a book entitled Omphalos (“the Navel”). The gist of this amazing book is that Adam, though he had no mother, was created with a navel, and that fossils were placed by the Creator where we find them now — a deliberate act on His part, to give the appearance of great antiquity and geologic upheavals. It is easy to see the fatal flaw in all such notions. They are blasphemies, accusing God of absurd deceitfulness. This is as revolting as it is uncalled for.

Diversity of Living Beings

The diversity and the unity of life are equally striking and meaningful aspects of the living world. Between 1.5 and 2 million species of animals and plants have been described and studied; the number yet to be described is probably as great. The diversity of sizes, structures, and ways of life is staggering but fascinating. Here are just a few examples.

The foot-and-mouth disease virus is a sphere 8-12 mm in diameter. The blue whale reaches 30 m in length and 135 t in weight. The simplest viruses are parasites in cells of other organisms, reduced to barest essentials minute amounts of DNA or RNA, which subvert the biochemical machinery of the host cells to replicate their genetic information, rather than that of the host.

It is a matter of opinion, or of definition, whether viruses are considered living organisms or peculiar chemical substances. The fact that such differences of opinion can exist is in itself highly significant. It means that the borderline between living and inanimate matter is obliterated. At the opposite end of the simplicity complexity spectrum you have vertebrate animals, including man. The human brain has some 12 billion neurons; the synapses between the neurons are perhaps a thousand times numerous.

Some organisms live in a great variety of environments. Man is at the top of the scale in this respect. He is not only a truly cosmopolitan species but, owing to his technologic achievements, can survive for at least a limited time on the surface of the moon and in cosmic spaces. By contrast, some organisms are amazingly specialized. Perhaps the narrowest ecologic niche of all is that of a species of the fungus family Laboulbeniaceae, which grows exclusively on the rear portion of the elytra of the beetle Aphenops cronei, which is found only in some limestone caves in southern France. Larvae of the fly Psilopa petrolei develop in seepages of crude oil in California oilfields; as far as is known they occur nowhere else. This is the only insect able to live and feed in oil, and its adult can walk on the surface of the oil only as long as no body part other than the tarsi are in contact with the oil. Larvae of the fly Drosophila carciniphila develop only in the nephric grooves beneath the flaps of the third maxilliped of the land crab Geocarcinus ruricola, which is restricted to certain islands in the Caribbean.

Is there an explanation, to make intelligible to reason this colossal diversity of living beings? Whence came these extraordinary, seemingly whimsical and superfluous creatures, like the fungus Laboulbenia, the beetle Aphenops cronei, the flies Psilopa petrolei and Drosophila carciniphila, and many, many more apparent biologic curiosities? The only explanation that makes sense is that the organic diversity has evolved in response to the diversity of environment on the planet earth. No single species, however perfect and however versatile, could exploit all the opportunities for living. Every one of the millions of species has its own way of living and of getting sustenance from the environment. There are doubtless many other possible ways of living as yet unexploited by any existing species; but one thing is clear: with less organic diversity, some opportunities for living would remain unexploited. The evolutionary process tends to fill up the available ecologic niches. It does not do so consciously or deliberately; the relations between evolution and environment are more subtle and more interesting than that. The environment does not impose evolutionary changes on its inhabitants, as postulated by the now abandoned neo-Lamarckian theories. The best way to envisage the situation is as follows: the environment presents challenges to living species, to which the later may respond by adaptive genetic changes.

An unoccupied ecologic niche, an unexploited opportunity for living, is a challenge. So is an environmental change, such as the Ice Age climate giving place to a warmer climate. Natural selection may cause a living species to respond to the challenge by adaptive genetic changes. These changes may enable the species to occupy the formerly empty ecologic niche as a new opportunity for living, or to resist the environmental change if it is unfavorable. But the response may or may not be successful. This depends on many factors, the chief of which is the genetic composition of the responding species at the time the response is called for. Lack of successful response may cause the species to become extinct. The evidence of fossils shows clearly that the eventual end of most evolutionary lines is extinction. Organisms now living are successful descendants of only a minority of the species that lived in the past and of smaller and smaller minorities the farther back you look. Nevertheless, the number of living species has not dwindled; indeed, it has probably grown with time. All this is understandable in the light of evolution theory; but what a senseless operation it would have been, on God’s part, to fabricate a multitude of species ex nihilo and then let most of them die out!

There is, of course, nothing conscious or intentional in the action of natural selection. A biologic species does not say to itself, “Let me try tomorrow (or a million years from now) to grow in a different soil, or use a different food, or subsist on a different body part of a different crab.” Only a human being could make such conscious decisions. This is why the species Homo sapiens is the apex of evolution. Natural selection is at one and the same time a blind and creative process. Only a creative and blind process could produce, on the one hand, the tremendous biologic success that is the human species and, on the other, forms of adaptedness as narrow and as constraining as those of the overspecialized fungus, beetle, and flies mentioned above.

Anti-evolutionists fail to understand how natural selection operates. They fancy that all existing species were generated by supernatural fiat a few thousand years ago, pretty much as we find them today. But what is the sense of having as many as 2 or 3 million species living on earth? If natural selection is the main factor that brings evolution about, any number of species is understandable: natural selection does not work according to a foreordained plan, and species are produced not because they are needed for some purpose but simply because there is an environmental opportunity and genetic wherewithal to make them possible. Was the Creator in a jocular mood when he made Psilopa petrolei for California oil fields and species of Drosophila to live exclusively on some body-parts of certain land crabs on only certain islands in the Caribbean? The organic diversity becomes, however, reasonable and understandable if the Creator has created the living world not by caprice but by evolution propelled by natural selection. It is wrong to hold creation and evolution as mutually exclusive alternatives. I am a creationist and an evolutionist. Evolution is God’s, or Nature’s method of creation. Creation is not an event that happened in 4004 BC; it is a process that began some 10 billion years ago and is still under way.

Unity of Life

The unity of life is no less remarkable than its diversity. Most forms of life are similar in many respects. The universal biologic similarities are particularly striking in the biochemical dimension. From viruses to man, heredity is coded in just two, chemically related substances: DNA and RNA. The genetic code is as simple as it is universal. There are only four genetic “letters” in DNA: adenine, guanine, thymine, and cytosine. Uracil replaces thymine in RNA. The entire evolutionary development of the living world has taken place not by invention of new “letters” in the genetic “alphabet” but by elaboration of ever-new combinations of these letters.

Not only is the DNA-RNA genetic code universal, but so is the method of translation of the sequences of the “letters” in DNA-RNA into sequences of amino acids in proteins. The same 20 amino acids compose countless different proteins in all, or at least in most, organisms. Different amino acids are coded by one to six nucleotide triplets in DNA and RNA. And the biochemical universals extend beyond the genetic code and its translation into proteins: striking uniformities prevail in the cellular metabolism of the most diverse living beings. Adenosine triphosphate, biotin, riboflavin, hemes, pyridoxin, vitamins K and B12, and folic acid implement metabolic processes everywhere.

What do these biochemical or biologic universals mean? They suggest that life arose from inanimate matter only once and that all organisms, no matter now diverse, in other respects, conserve the basic features of the primordial life. (It is also possible that there were several, or even many, origins of life; if so, the progeny of only one of them has survived and inherited the earth.) But what if there was no evolution and every one of the millions of species were created by separate fiat? However offensive the notion may be to religious feeling and to reason, the anti-evolutionists must again accuse the Creator of cheating. They must insist that He deliberately arranged things exactly as if his method of creation was evolution, intentionally to mislead sincere seekers of truth.

The remarkable advances of molecular biology in recent years have made it possible to understand how it is that diverse organisms are constructed from such monotonously similar materials: proteins composed of only 20 kinds of amino acids and coded only by DNA and RNA, each with only four kinds of nucleotides. The method is astonishingly simple. All English words, sentences, chapters, and books are made up of sequences of 26 letters of the alphabet. (They can be represented also by only three signs of the Morse code: dot, dash, and gap.) The meaning of a word or a sentence is defined not so much by what letters it contains as by the sequences of these letters. It is the same with heredity: it is coded by the sequences of the genetic “letters” the nucleotides in the DNA. They are translated into the sequences of amino acids in the proteins.

Molecular studies have made possible an approach to exact measurements of degrees of biochemical similarities and differences among organisms. Some kinds of enzymes and other proteins are quasi-universal, or at any rate widespread, in the living world. They are functionally similar in different living beings, in that they catalyze similar chemical reactions. But when such proteins are isolated and their structures determined chemically, they are often found to contain more or less different sequences of amino acids in different organisms. For example, the so-called alpha chains of hemoglobin have identical sequences of amino acids in man and the chimpanzee, but they differ in a single amino acid (out of 141) in the gorilla. Alpha chains of human hemoglobin differ from cattle hemoglobin in 17 amino acid substitutions, 18 from horse, 20 from donkey, 25 from rabbit, and 71 from fish (carp).

Cytochrome C is an enzyme that plays an important role in the metabolism of aerobic cells. It is found in the most diverse organisms, from man to molds. E. Margoliash, W. M. Fitch, and others have compared the amino acid sequences in cytochrome C in different branches of the living world. Most significant similarities as well as differences have been brought to light. The cytochrome C of different orders of mammals and birds differ in 2 to 17 amino acids, classes of vertebrates in 7 to 38, and vertebrates and insects in 23 to 41; and animals differ from yeasts and molds in 56 to 72 amino acids. Fitch and Margoliash prefer to express their findings in what are called “minimal mutational distances.” It has been mentioned above that different amino acids are coded by different triplets of nucleotides in DNA of the genes; this code is now known. Most mutations involve substitutions of single nucleotides somewhere in the DNA chain coding for a given protein. Therefore, one can calculate the minimum numbers of single mutations needed to change the cytochrome C of one organism into that of another. Minimal mutational distances between human cytochrome C and the cytochrome C of other living beings are as follows:

Monkey	1	Chicken	18
Dog	13	Penguin	18
Horse	17	Turtle	19
Donkey	16	Rattlesnake	20
Pig	13	Fish (tuna)	31
Rabbit	12	Fly	33
Kangaroo	12	Moth	36
Duck	17	Mold	63
Pigeon	16	Yeast	56

It is important to note that amino acid sequences in a given kind of protein vary within a species as well as from species to species. It is evident that the differences among proteins at the level of species, genus, family, order, class, and phylum are compounded of elements that vary also among individuals within a species. Individual and group differences are only quantitatively, not qualitatively, different. Evidence supporting the above propositions is ample and is growing rapidly. Much work has been done in recent years on individual variations in amino acid sequences of hemoglobin of human blood. More that 100 variants have been detected. Most of them involve substitutions of single amino acids – substitutions that have arisen by genetic mutations in the persons in whom they are discovered or in their ancestors. As expected, some of these mutations are deleterious to their carriers, but others apparently are neutral or even favorable in certain environments. Some mutant hemoglobins have been found only in one person or in one family; others are discovered repeatedly among inhabitants of different parts of the world. I submit that all these remarkable findings make sense in the light of evolution: they are nonsense otherwise.

Comparative Anatomy and Embryology

The biochemical universals are the most impressive and the most recently discovered, but certainly they are not the only vestiges of creation by means of evolution. Comparative anatomy and embryology proclaim the evolutionary origins of the present inhabitants of the world. In 1555 Pierre Belon established the presence of homologous bones in the superficially very different skeletons of man and bird. Later anatomists traced the homologies in the skeletons, as well as in other organs, of all vertebrates. Homologies are also traceable in the external skeletons of arthropods as seemingly unlike as a lobster, a fly, and a butterfly. Examples of homologies can be multiplied indefinitely.

Embryos of apparently quite diverse animals often exhibit striking similarities. A century ago these similarities led some biologists (notably the German zoologist Ernst Haeckel) to be carried by their enthusiasm as far as to interpret the embryonic similarities as meaning that the embryo repeats in its development the evolutionary history of its species: it was said to pass through stages in which it resembles its remote ancestors. In other words, early-day biologists supposed that by studying embryonic development one can, as it were, read off the stages through which the evolutionary development had passed. This so-called biogenetic law is no longer credited in its original form. And yet embryonic similarities are undeniable impressive and significant.

Probably everybody knows the sedentary barnacles which seem to have no similarity to free-swimming crustaceans, such as the copepods. How remarkable that barnacles pass through a free-swimming larval stage, the nauplius! At that stage of its development a barnacle and a Cyclops look unmistakably similar. They are evidently relatives. The presence of gill slits in human embryos and in embryos of other terrestrial vertebrates is another famous example. Of course, at no stage of its development is a human embryo a fish, nor does it ever have functioning gills. But why should it have unmistakable gill slits unless its remote ancestors did respire with the aid of gills? It is the Creator again playing practical jokes?

Adaptive radiation: Hawaii’s Flies

There are about 2,000 species of drosophilid flies in the world as a whole. About a quarter of them occur in Hawaii, although the total area of the archipelago is only about that of the state of New Jersey. All but 17 of the species in Hawaii are endemic (found nowhere else). Furthermore, a great majority of the Hawaiian endemics do not occur throughout the archipelago: they are restricted to single islands or even to a part of an island. What is the explanation of this extraordinary proliferation of drosophilid species in so small a territory? Recent work of H. L. Carson, H. T. Spieth, D. E. Hardy, and others makes the situation understandable.

The Hawaiian Islands are of volcanic origin; they were never parts of any continent. Their ages are between 5.6 and 0.7 million years. Before man came there inhabitants were descendants of immigrants that had been transported across the ocean by air currents and other accidental means. A single drosophilid species, which arrived in Hawaii first, before there were numerous competitors, faced the challenge of an abundance of many unoccupied ecologic niches. Its descendants responded to this challenge by evolutionary adaptive radiation, the products of which are the remarkable Hawaiian drosophilids of today. To forestall a possible misunderstanding, let it be made clear that the Hawaiian endemics are by no means so similar to each other that they could be mistaken for variants of the same species; if anything, they are more diversified than are drosophilids elsewhere. The largest and the smallest drosophilid species are both Hawaiian. They exhibit an astonishing variety of behavior patterns. Some of them have become adapted to ways of life quite extraordinary for a drosophilid fly, such as being parasites in egg cocoons of spiders.

Oceanic islands other than Hawaii, scattered over the wide Pacific Ocean, are not conspicuously rich in endemic species of drosophilids. The most probable explanation of this fact is that these other islands were colonized by drosophilid after most ecologic niches had already been filled by earlier arrivals. This surely is a hypothesis, but it is a reasonable one. Anti-evolutionists might perhaps suggest an alternative hypothesis: in a fit of absentmindedness, the Creator went on manufacturing more and more drosophilid species for Hawaii, until there was an extravagant surfeit of them in this archipelago. I leave it up to you to decide which hypothesis makes sense.

Strength and Acceptance of the Theory

Seen in the light of evolution, biology is, perhaps, intellectually the most satisfying and inspiring science. Without that light it becomes a pile of sundry facts some of them interesting or curious but making no meaningful picture as a whole.

This is not to imply that we know everything that can and should be known about biology and about evolution. Any competent biologist is aware of a multitude of problems yet unresolved and of questions yet unanswered. After all, biologic research shows no sign of approaching completion; quite the opposite is true. Disagreements and clashes of opinion are rife among biologists, as they should be in a living and growing science. Anti-evolutionists mistake, or pretend to mistake, these disagreements as indications of dubiousness of the entire doctrine of evolution. Their favorite sport is stringing together quotations, carefully and sometimes expertly taken out of context, to show that nothing is really established or agreed upon among evolutionists. Some of my colleagues and myself have been amused and amazed to read ourselves quoted in a way showing that we are really anti-evolutionists under the skin.

Let me try to make crystal clear what is established beyond reasonable doubt, and what needs further study, about evolution. Evolution as a process that has always gone on in the history of the earth can be doubted only by those who are ignorant of the evidence or are resistant to evidence, owing to emotional blocks or to plain bigotry. By contrast, the mechanisms that bring evolution about certainly need study and clarification. There are no alternatives to evolution as history that can withstand critical examination. Yet we are constantly learning new and important facts about evolutionary mechanisms.

It is remarkable that more than a century ago Darwin was able to discern so much about evolution without having available to him the key facts discovered since. The development of genetics after 1900 especially of molecular genetics, in the last two decades has provided information essential to the understanding of evolutionary mechanisms. But much is in doubt and much remains to be learned. This is heartening and inspiring for any scientist worth his salt. Imagine that everything is completely known and that science has nothing more to discover: what a nightmare!

Does the evolutionary doctrine clash with religious faith? It does not. It is a blunder to mistake the Holy Scriptures for elementary textbooks of astronomy, geology, biology, and anthropology. Only if symbols are construed to mean what they are not intended to mean can there arise imaginary, insoluble conflicts. As pointed out above, the blunder leads to blasphemy: the Creator is accused of systematic deceitfulness.

One of the great thinkers of our age, Pierre Teilhard de Chardin, wrote the following: “Is evolution a theory, a system, or a hypothesis? It is much more it is a general postulate to which all theories, all hypotheses, all systems much henceforward bow and which they must satisfy in order to be thinkable and true. Evolution is a light which illuminates all facts, a trajectory which all lines of though must follow this is what evolution is. Of course, some scientists, as well as some philosophers and theologians, disagree with some parts of Teilhard’s teachings; the acceptance of his worldview falls short of universal. But there is no doubt at all that Teilhard was a truly and deeply religious man and that Christianity was the cornerstone of his worldview. Moreover, in his worldview science and faith were not segregated in watertight compartments, as they are with so many people. They were harmoniously fitting parts of his worldview. Teilhard was a creationist, but one who understood that the Creation is realized in this world by means of evolution.”

Contributor: B. Crees