Pamela Lyon writes:

In On the Origin of Species (1859), Charles Darwin draws a picture of the long sweep of evolution, from the beginning of life, playing out along two fundamental axes: physical and mental. Body and mind. All living beings, not just some, evolve by natural selection in both ‘corporeal and mental endowments’, he writes. When psychology has accepted this view of nature, Darwin predicts, the science of mind ‘will be based on a new foundation’, the necessarily gradual evolutionary development ‘of each mental power and capacity’.

Darwin guessed that life arose from a single ancestral ‘form’, presumed to be single-celled. Soon, scientists in Germany, France and the United States began investigating microscopic organisms for evidence of ‘mental faculties’ (perception, memory, decision-making, learning). All three groups were headed by men destined for eminence. Two of them – Alfred Binet, the psychologist who devised the first practical intelligence test, and Herbert Spencer Jennings, who laid the foundations of mathematical genetics – were persuaded by their research that Darwin was right: behaviour even in microbes suggests that mental as well as physical evolution exists. Max Verworn, a giant of German physiology, was unconvinced.

Thus kicked off a heated debate about the continuity of mental evolution, the idea that what in humans is called ‘mind’ and in other animals is usually called ‘cognition’ developed and changed over millions of years (billions, actually). That debate continues to this day. The rise of behaviourism in the early 1900s, which privileged observable behaviour as the only admissible scientific data, curtailed discussion by taking talk about minds off the table for decades. When the ‘cognitive revolution’ launched mid-century, discontinuity was firmly established. The consensus was that, at some point in evolution (and we might never know when), cognition – poof! – somehow appears in some animals. Before that, behaviour – the only indicator of cognition available without language – would have been entirely innate, machine-like, reflexive. It might have looked cognitively driven but wasn’t. This remains the dominant view, almost entirely on the grounds of its ‘intuitive’ plausibility based on commonsense understanding.

The philosopher Daniel Dennett, among the earliest cognitive philosophers to invoke evolution, dubbed natural selection ‘Darwin’s dangerous idea’ because it showed that the appearance of design in nature requires no designer, divine or otherwise. Like most of his colleagues, philosophical and scientific, Dennett didn’t buy the continuity of mental evolution. However, my view is that this neglected insight of Darwin’s was his most radical idea, one with the potential to induce a full-blown Copernican revolution in the cognitive sciences and to transform the way we see the world and our place in it. [Continue reading…]