When Charles Darwin published On the Origin of Species in 1859, the Industrial Revolution and British colonialism were in the ascendant. Charles Dickens had published Hard Times five years earlier; Queen Victoria nominally ruled a fifth of the world’s population. Darwin, writes science writer Rowan Hooper, crafted his evolutionary theory to deliver what he figured his audience wanted to hear: “an account of nature as a competitive struggle”. Natural selection was launched into a world that was “colonial, capitalist, patriarchal and ruled by the upper class” – and Darwin’s central message, crudely paraphrased by the philosopher Herbert Spencer as “survival of the fittest”, chimed with the times.
Hooper adores Darwin – his account of visiting Darwin’s Kent residence Down House radiates reverence (“it’s a pseudo-religious experience”). But he feels that Darwinism and its union with genetics in the so-called “modern synthesis” has placed undue emphasis on competition in the natural world and underplayed the roles of cooperation and collaboration. In redressing that imbalance, Togetherness is not an attempt to make evolution cuddlier and more palatable; rather, it is a corrective deeply informed by what we have learned since Darwin about how nature works. Written with immense charm and passion, and packed with eye-popping facts, it is also a paean to the wonders of nature and the value and urgency of preserving them.
It’s easy enough to see the competitive side of nature: the lion stalking a gazelle, the bird of prey swooping for the kill. But the photogenic animal world is not necessarily the most representative resource for the natural historian. Hooper shows that we often find a very different story among the soft, slimy and squishy stuff: moulds, microbes, mushrooms. And lichens, which look superficially plant-like but are in fact a partnership between fungi and algae. Each supplies something the other needs: algae can photosynthesise, producing carbohydrates on which fungi feed, while the fungi shelter and spread the light-gathering algae. The relationship is symbiotic: each organism is dependent on the other and they grow and evolve together. Sometimes the lichen collective is joined by other partners: cyanobacteria (photosynthetic bacteria) or yeast. It’s a fantastically productive partnership, enabling lichens to flourish almost anywhere, from rainforests to tundra and deserts.
Or take corals. These colourful, branched marine organisms invite classification as plants but are in fact collaborations of animals (cnidarians, from the same family as sea anemones and jellyfish) and algae that live in their stomachs. The algae photosynthesise using sunlight while the host animal delivers nutrients and carbon dioxide to their guests. (Some deep-sea corals, growing in the dark, host bacteria instead.) Darwin published a book on coral reefs in 1842 after seeing them on the voyage of the Beagle, explaining how their limestone shells created entire island atolls. But he had no idea they were symbionts.
Most land plants depend on symbiotic fungi, especially the root fungi called mycorrhizae that deliver vital nutrient elements such as nitrogen and phosphorus. Without these associations there would be no forests and prairies covering the land, but just mats and crusts of microbial colonies. Orchids are the archetypal plant symbiont – individual plants are interlinked via an underground fungal network along which they can send sugar to their seedlings.
These are not, as was first imagined, oddities: symbiosis is the natural state of most organisms. Beetles and termites cultivate nutritious fungal gardens in their nests. And the importance of the bacteria hosted in and on our bodies – our microbiome – has become increasingly apparent. Antibiotics that deplete them leave us with digestive disorders, while some recurrent bacterial infections and even depression can be treated with faecal transplants, which sound gross but are nothing more nor less than a restocking of our microbial collaborators.
Symbiosis has driven evolution since its earliest days. The chloroplasts responsible for photosynthesis in plant cells were once free-living cyanobacteria. So were the mitochondria that produce energy in our own cells. Such permanent symbiotic merging (endosymbiosis) of single-celled organisms was first proposed in the 1960s by biologist Lynn Margulis, who asserted that the “red in tooth and claw” Darwinian view of evolution was “naive”. “Now we see ourselves as products of cellular interaction,” she wrote in 1987. Such mergers, she said, could allow evolution to advance not in small steps but in great leaps.
Margulis’s endosymbiosis hypothesis is now accepted, but initially met scepticism and even ridicule. Sexism surely played a part in that, but there’s a thesis to be written on the resistance of academic biology to notions of cooperation and collaboration in evolution – or the determination to recast them as mere expediency by “selfish genes”. Margulis made the rather gender-essentialist claim that scepticism about symbiosis was a rejection of the “feminine”, but one can’t help noticing that an emphasis on interconnection in the natural world often came from women, whether it was Rachel Carson’s Silent Spring or the “wood wide web” of forestry scientist Suzanne Simard, the inspiration for a character in Richard Power’s 2018 eco-fable The Overstory.
These interdependencies are vital to the health of the biosphere. The catastrophic “bleaching” of coral reefs caused by warming of the oceans, for example, happens because the symbiotic algae can’t stand the warmer water. Without them, corals are doomed, and reefs have already declined by half since the mid-20th century. But, as Hooper explains, symbiosis is itself a delicate balance and apt to tip into parasitism if one partner reneges on the arrangement. He warns, however, that ultimately the language of competition and collaboration is anthropomorphic and tends to impose moral judgment on the workings of nature.
My review copy of Togetherness is now peppered with marginal annotations of “Wow!” I never knew that the feelgood neurotransmitter serotonin is mostly made by our gut bacteria. Some ants produce antibiotics that they apply to nestmates’ wounds. The bacterial symbionts of cockroaches give them their infernal (to our view) ability to live almost anywhere and eat almost anything. Hooper’s background in conservation biology and his wide travels (I guess being an editor at New Scientist has its perks) bring vividness to his accounts. While he mistakenly asserts that living organisms reduce entropy, seems sometimes to conflate symbiosis and interdependence (predators still need their prey), and somewhat exaggerates the “outrage and panic” that Darwin’s Origin produced among “religious authorities”, these are minor quibbles.
Darwin himself was too astute a naturalist to ignore the interdependencies of nature. He didn’t know the symbiotic secrets of corals or lichens, but he was fascinated by orchids, and an ecological sensibility, as we’d now see it, pervades his writings. The famous final passage of Origin (“endless forms most beautiful”) stresses not the ruthless individualism of nature but its webs of coexistence. “It is interesting,” Darwin wrote, “to contemplate an entangled bank, clothed with many plants of many kinds … these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner.”
This is the Darwinian message we need most to hear today. “The crisis of nature we are engulfed in has been caused by a failure to see in ecological terms, a failure set up by our philosophical and economic systems,” writes Hooper. “We are symbiotic creatures at the deepest level of our cells.” A feeling of oneness with nature, he says, is not woolly green fantasy or pre-scientific mysticism. It reflects our best understanding of life and should be heeded.