Michael Bond writes:

On Dartmoor, in southwest England, search and rescue volunteers are regularly called out to look for people who have lost their way in the boundless wilderness. A significant proportion are Alzheimer’s patients who have wandered away from one of the many care homes on the fringes of the moor. The volunteers have noticed that Alzheimer’s patients move in a particular way across the open spaces: usually in a straight line. So resolutely do they stick to their chosen direction that they will often attempt to plunge headlong through whatever lies in their way. More than once, rescue teams on Dartmoor have retrieved elderly men from the middle of gorse thickets: they simply kept on going until they could go no further.

Alzheimer’s is commonly understood to be a disease of memory, and its effect on memory is certainly catastrophic. But more fundamentally it is a disease of orientation, a slow severing of ties with our surroundings. It particularly affects the brain’s spatial areas, such as the hippocampus and entorhinal cortex, and spatial lapses are among the very first symptoms – misplacing keys more often than usual, getting con­fused on a regular route or finding it impossible to learn a new one. As the illness advances, patients inhabit an ever-diminishing ‘life space’, until their confusion makes it difficult for them to go beyond their own room. Alzheimer’s sufferers who go missing on Dartmoor are lost even before they leave their homes. Their spatial awareness has collapsed to a single dimension, and they are left, literally, with nowhere to turn.

In the age of GPS, we tend to take our navigation and spatial abilities for granted, until they – or the technology – let us down. It is easy to forget that they have sustained us for tens of thousands of years. Over the course of our evolution, Homo sapiens developed an appetite for exploration and a wayfinding spirit that set us apart from previous human species. It had a huge effect on our future. One of the most intriguing recent ideas in anthropology is that our ability to navigate was essential to our success as a species, because it allowed us to cultivate extensive social networks. In prehistoric times, when people lived in small family units and spent much of their time looking for food and shelter, being able to share information with other groups about the whereabouts of resources and the movements of predators would have given us an evolutionary edge. Friends were a survival asset: if you ran out of food, you knew where to go; if you needed help on a hunt, you knew whom to ask.

Maintaining those social networks across tens or hundreds of square miles of Palaeolithic wilderness would have required navigation skills, spatial awareness, a sense of direction and the ability to store mental maps of the landscape. The Canadian anthropologist Ariane Burke believes that our ancestors developed these attributes while trying to keep in touch with their neighbours. ‘Those far-flung networks were essential to our culture,’ she told me. ‘During the Palaeolithic, there were comparatively few people around. Maintaining a spatially extensive social network was a way of ensuring your continued survival. You would need a very dynamic cognitive map, which you would constantly have to update with information about your contacts and what they were telling you about the landscape.’ In this way, the human brain became primed for wayfinding. Navigation and spatial awareness are part of our DNA. [Continue reading…]