Entangled Life

Whether one calls slime moulds, fungi and plants ‘intelligent’ depends on one’s point of view. Classical scientific definitions of intelligence use humans as a yardstick by which all other species are measured. According to these anthropocentric definitions, humans are always at the top of the intelligence rankings, followed by animals that look like us (chimpanzees, bonobos, etc.), followed again by other higher animals, and onwards and downwards in a league table – a great chain of intelligence drawn up by the ancient Greeks, which persists one way or another to this day. Because these organisms don’t look like us or outwardly behave like us – or have brains – they have traditionally been allocated a position somewhere at the bottom of the scale. Too often they are thought of as the inert backdrop to animal life. Yet many are capable of sophisticated behaviours that prompt us to think in new ways about what it means for organisms to ‘solve problems’, ‘communicate’, ‘make decisions’, ‘learn’ and ‘remember’. As we do so, some of the vexed hierarchies that underpin modern thought start to soften. As they soften, our ruinous attitudes towards the more-than-human world may start to change.¹⁷

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Learning more about these associations changes our experiences of our own bodies and the places we inhabit. ‘We’ are ecosystems that span boundaries and transgress categories. Our selves emerge from a complex tangle of relationships only now becoming known.¹⁹

In 1967, the visionary American biologist Lynn Margulis became a vocal proponent of a controversial theory that gave symbiosis a central role in the evolution of early life. Margulis argued that some of the most significant moments in evolution had resulted from the coming together – and staying together – of different organisms. Eukaryotes arose when a single-celled organism engulfed a bacterium, which continued to live symbiotically inside it. Mitochondria were the descendants of these bacteria. Chloroplasts were the descendants of photosynthetic bacteria that had been engulfed by an early eukaryotic cell. All complex life that followed, human life included, was a story of the long-lasting ‘intimacy of strangers’.²³

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The endosymbiotic theory, as it came to be known, rewrote the history of life. It was one of the twentieth century’s most dramatic shifts in biological consensus. The evolutionary biologist Richard Dawkins went on to congratulate Margulis on ‘sticking by’ the theory, ‘from unorthodoxy to orthodoxy’ It is one of the great achievements of twentieth-century evolutionary biology; Dawkins continued, ‘and I greatly admire Lynn Margulis’s sheer courage and stamina.’ The philosopher Daniel Dennett described Margulis’ theory as ‘one of the most beautiful ideas [he’d] ever encountered’, and Margulis as ‘one of the heroes of twentieth-century biology’. ²⁶