by Rafe Sagarin
Second, symbiotic relationships are incredibly diverse. There are the obvious ones we see every day, like butterflies, bees, bats, and hummingbirds getting nectar from flowers in exchange for pollinating the plants and maintaining genetic mixing. But some flowers also form a symbiosis with the yeast that sometimes clings to these pollinators, giving the yeast nectar to thrive on and getting warmth from the metabolic activity of the yeast, which in turn allows the flower to release more of the chemicals that attract pollinators in the first place.4 There is no one pathway toward successful symbioses between species.
Third, symbiosis creates reactions that are more than just the sum of two organisms working together. Symbiosis creates emergent properties that you wouldn’t predict from just looking at the two organisms on their own. That is to say, symbiosis transforms an organism and transforms the environment around the organism. The relationship creates whole networks of interactions, builds new habitats for other species to use, and even changes the tenor of conflict in the larger ecosystem. Lichens, which grow proficiently on bare rock and even in icy valleys of Antarctica, are actually a symbiotic partnership of fungi, algae, and bacteria. Through the process of their cooperative growth, they physically break down bare rock into usable soil that completely unrelated plants and animals can thrive in. The lichen’s contribution is not trivial— it’s estimated that the biomass of lichens on Earth exceeds the entire biomass of the world’s oceans.5 Deep-sea fish ensconce light-emitting, or bioluminescent, bacteria within special organs on their skin, so that they are able to hunt and lure prey in the inky black depths. In an amazing show of “convergent evolution,” symbiotic bioluminescence has evolved many times independently. More precisely, the ability to glow may have evolved only once in bacteria, but many different fish, squids, and other invertebrates have independently evolved their own structures to house these valuable bacteria,6 an amazing feat of transformation, facilitated by a tiny bacterium.
Other transformations are grotesque—some parasites actually force their host to change its behavior to further serve the parasite. There are worms that change the behavior and appearance of their ant hosts so the ants resemble fruits favored by birds that serve as the final host of the parasite. Parasites on small aquatic crustaceans called amphipods cause them to abandon their normal behavior of hiding under rocks and instead swim to the surface, where they are ingested by birds that serve as a definitive host within which the parasite can reproduce.7 Humans don’t escape this manipulation. Guinea worms—the treatment of which I will discuss below as one of the great success stories of human social symbiosis—are ingested by humans who drink water with guinea worm–infected fleas. Once inside the body, they cause intense burning pain in their human hosts, which causes people to seek out water to soak their skin, allowing the worm to release its larvae, which can then reinfect the water that another potential human host will drink.8
But the behavioral changes created by symbiosis may have wider benefits as well. Studies on monkeys and apes show that when individuals are forced to begin a cooperative relationship (to help one another get food, for example), conflict overall between the animals is reduced.9 Large fish on coral reefs that develop symbiotic relationships with cleaner wrasses—small fish that set up “cleaning stations” to eat parasites out of the larger fish’s mouth and gills—are less aggressive not only to their cleaning partners but toward all other fish on the reef as well.10
The early-twentieth-century ecologist Warder Allee was a lifelong proponent of the transformative capacity of relationships among natural organisms. Over decades of natural history observations and experiments in his lab, he studied two major aspects of the social relationships of animals. First, he studied the supposedly cruel part of biology—the fierce competition for resources, the pecking orders, and dominance hierarchies that pitted one member of a group against another. But he also studied, and one suspects greatly favored, the cooperative side of nature, the deliberately altruistic and instinctual connections to other living beings, what he called “automatic” cooperation between animals of the same and different species.
Where Allee did look at tooth-and-claw competition, he generally saw it as a stabilizing force. But his perspective wasn’t that of a Victorian Social Darwinist; in his view, it wasn’t the sole “alpha” individual, through its superior breeding and intellect, that rightfully kept the other inferior subjects properly in line. Rather, he saw that the interactions between organisms in a pecking order were essential to the group’s overall stability. In one test of this idea he observed pecking orders in two hen houses. In one, the chickens were allowed to develop a normal dominance hierarchy, and Allee observed that this stayed stable for months at a time, maintained by constant small reminders—little pecks—between more and less dominant individuals. In the other house, the hen that emerged as dominant was always removed after a few days, throwing the pecking order into chaos. In this house, there was far more violent fighting as power vacuums continually opened up.
But it was cooperation that enthralled Allee. He collected dozens and dozens of examples of cooperation through his own painstaking laboratory experiments, field observations, and reviews of decades of biological research. He found embryos that cleaved faster when fertilized in groups. Protozoans, which reproduce through cleavage, produced much greater numbers when two were put together in a dish than the combined numbers of clones produced by two individuals housed separately. Goldfish in groups survived longer when exposed to toxic silver than they did as individuals exposed to a proportional amount of the same toxin. Male manakin birds in Panama formed lines in forest clearings, singing to attract females. Although they were competing for mates, working in a group was much more effective in attracting females than if they sang alone in isolated patches.
Allee worked to reconcile these two apparently contradictory biological forces—competition and cooperation—not just in the strictly biological realm, but as they related to the social affairs of humans. He reminded readers that Adam Smith, whose The Wealth of Nations is practically a Bible for libertarians and free-market conservatives railing against government regulation, also wrote The Theory of Moral Sentiments, which suggests that sympathy for fellow humans is an essential force that counteracts the self-interested nature of humans.11 And from Allee’s hen-house experiments he extrapolated, “Person to person competition, if not too severe, may lead to group organization which increases the effectiveness of the group as a cooperating social unit in competition or cooperation with other social organizations.”12
This statement suggests the kind of nested, recursive process that we see all over biological systems. That is, if competition within a group creates group cooperation that can be used in the group’s competitions with other groups, then those higher-level competitions should lead to cooperation between the groups that can be then used at yet higher-level competition. In this view, cooperation, like learning, is its own evolutionary force that contributes to an organism’s immediate survival but also creates the possibility for adaptive responses to future challenges.
In the end, although Allee felt that both the “egoistic” and cooperative forces were essential for evolution, he had much more belief in cooperation than the brutish stability of dominance hierarchies as a model for human affairs. He argued that each more complex level of biological organization, as well as each more complex organism in evolutionary history, was built on the foundation of cooperative arrangements at the levels below or before them.13 For example, multicellular organisms could never exist if some form of lasting cooperation did not occur between their single-celled ancestors.
Allee’s bias toward cooperation is owed in part to his understanding that all biological and social systems change, and he saw cooperative relationships, rather than dominance hierarchies, as adaptable to change. That he eagerly brought this bias to his speculations about human social relations likely stems from his personality and the time period in which he lived—he was an optim
ist living in a time of global upheaval. His work and life were bracketed by two world wars and were witness to the collapse of longstanding empires and the relatively quick termination of newer empires in Germany and Japan, brought about by extremely costly but effective cooperation among nations. Unlike the typical Social Darwinist, Allee saw biological tendencies as pointing decidedly away from warfare:Such evidence and reasoning as I have presented indicates pretty clearly that the present system of international relations [based on war] is biologically unsound. Attempts that have been made in the past to lend biological respectability to the existing system by regarding it as an expression of an inevitable struggle for existence have overlooked not only its defects as a selecting agent, but more serious, have often not even been conscious of the existence of another fundamental biological principle, that of cooperation.14
With this worldview, Allee saw the postwar era as an opportune time to create a cooperative organization among nations, to ensure a lasting peace. While this was a common sentiment of the era, and ultimately led to the United Nations, his perspective was unique in that he felt that the design of this organization should be biologically based, noting that “the biologist’s international system must be a dynamic organization capable of and designed to effect changes rather than set up to preserve any given status quo, regardless of how favorable for the predominant powers.”15
In particular, Allee defended the creation of such a large organization by insisting that it take on the same nested and recursive processes seen in nature: “The maintenance of smaller cooperative and competing units within the larger one is part of the scheme as sketched.”16 This type of organization mirrors the decentralized adaptable organizations I discussed in Chapter 4, but is sadly quite different than the international bureaucracies—the United Nations, the International Monetary Fund, and the World Bank—that ultimately came into being after World War II.
Jean-François Rischard, a former World Bank president, has recognized the failure of these organizations to be adaptable to pressing world needs. His solution is to facilitate the creation of “global issues networks”—essentially bottom-up nongovernmental partnerships of individuals and groups that are borne out of local motivation to find solutions to specific problems.17 Rischard’s vision, which provides a pathway to create cooperation among entities that are currently in conflict, such as government and industry, is essentially an updating of Allee’s “biological” vision for a global peace-keeping entity.
Allee’s ideas fell out of favor soon after his death in 1955, which coincided roughly with the discovery of the structure of DNA and the rise of molecular biology. I think the two events are related. Watson and Crick’s explanation of the elegant structure of the molecule of life set off a revolution in biology, creating a chain reaction of amazing discoveries about life that have continued to emerge to this day. But the direction this revolution led was decidedly away from the natural history–based observations of Allee and even more so away from his ideas about broad-scale cooperation. Molecular biology was all about incredible things happening at very small scales. DNA imprinted individuals, not groups, and when natural selection happened it happened to individuals and to genes themselves, certainly not to groups. And if his notions about cooperation and group behaviors seemed antiquated in the new, more precise world of molecules, Allee’s broad speculations about what the pecking orders of chickens say about the affairs of man seemed completely unglued, the ramblings of a doddering old naturalist in an era where answers came by focusing ever sharper at ever smaller scales of life.
But now Allee’s ideas are coming back into favor. It started a few decades ago as biologists became alarmed at the global decline of many populations of plants and animals.18 We began to refer to “Allee effects” to talk about the minimum critical mass of animals needed to keep a population going. For example, as abalone are depopulated on the West Coast due to overfishing and disease, they may simply not live in dense enough aggregations for their free-floating eggs and sperm to meet in the turbulent Pacific waters, and thus their decline is accelerated. This attribution alone would be a nice footnote to Allee’s contributions, at least worthy of the short Wikipedia entry that bears his name.19 But the more fundamental, and I’d argue more important, contribution from Allee—that cooperation is a fundamental biological force—is also coming back to the fore, this time repackaged in the more inclusive concept of symbiosis.
THE UBIQUITY OF SYMBIOSIS
The transformative power of symbiosis is best illustrated in the concept of symbiogenesis, the idea that many integral parts of organisms today were once independent free living organisms themselves. In a symbiogenetic view, the world trends toward ever more cooperation, even as it grows more complex. Ironically, while it may have been genetics that stalled serious further exploration of Allee’s ideas, it was a hardened geneticist (albeit one with a nonconformist streak) who helped bring it back.
Lynn Margulis, who is now a well-respected member of the National Academy of Sciences and credited for her work advancing symbiogenetic theory, was once a scrappy student who advanced herself to upper grades in Chicago public schools under not entirely forthright premises and graduated from the University of Chicago at age nineteen.20 It’s a good thing that Margulis was both brilliant and a nonconformist, because she began her career in genetics by focusing not on the cell nucleus where DNA is concentrated (and where nearly all her colleagues were focused), but on the oddball genes hiding out in organelles like mitochondria, in the soupy cell cytoplasm outside of the nucleus. By looking where most other scientists were not, she was among the first to identify likely targets of symbiogenesis and develop a credible theory of how symbiogenesis could come to be. Like her public school records, her ideas were once considered fanciful fabrications. But just as she proved to her Chicago public school that she was more than competent at her adopted grade level, her work ultimately bore out the validity, indeed the ubiquity, of symbiotic origins of complex life forms and essential life processes, like photosynthesis and energy conversion. Where this idea merges with Allee’s earlier view of cooperation is that Margulis sees symbiosis as arising out of conflict that transitioned into cooperation. In her words, symbiosis is “a palpable legacy of a violent, competitive and truce-forming past.”21
This creative tension between competition and cooperation expressed in symbiosis is an intriguing window into human conflict, which is also a product of competitive and cooperative elements. We tend to focus on the obvious—that competition, even violent competition, is widespread across human societies. It is found between individuals, families, villages, cities, schools, sports teams, religions, and nations. But so too is cooperation widespread in human societies, as it is among social animals such as bees and wolves.
The roots of competition seem fairly obvious, but there is still spirited debate over how cooperation arises. Why would we want to help another individual, especially when there is likely to be a cost to us for doing so? In some views, cooperation arises from strict cost-benefit analysis. The benefit to my reproductive fitness—the likelihood of passing my genes to my offspring—or even just being acknowledged for my cooperative spirit may outweigh the cost of not being selfish. If a potential mate finds me more attractive because I help an old lady across the street, that is certainly worth the cost of time wasted.
Alternatively, this cost-benefit may not be deviously figured in material terms but rather calculated subconsciously in the currency of genetic relatedness. This is the concept of “kin selection,” in which there is a measurable benefit of helping and protecting not just yourself but those who are closely related to you genetically. This is why workers of some bee colonies (who are all sisters) will protect the hive to their deaths—if they can help their closely related sisters live, it may be worth sacrificing their own life. But kin selection isn’t a satisfactory explanation of cooperation in humans. We help fellow humans who are only distantly genetically related, and we even help ot
her species who are more distantly related, sometimes sacrificing our own lives in the process.
Cooperation may also arise through the expectation of reciprocity, so that every apparently altruistic act comes with an expectation of a return. If a chimp picks the fleas off another chimp and the other returns the favor later, they are more likely to cooperate in the future.22
On the flip side, cooperation may also arise due to fear—there could be social ostracism or more serious punishments for those who don’t cooperate. Workers in some insect societies that don’t work but instead try to lay their own eggs are punished by the queen, who might kick the cheater out of the nest, or by fellow workers, who may destroy eggs not laid by the queen.23