December 27, 2013
Hunter-gatherers search for food in the same way as animals including sharks and honeybees, according to anthropologists.
The Hadza tribe – one of the last big game hunters in Africa – hunt for food in a way that is described by a mathematical pattern called a Lévy walk.
The pattern is found in the movements of lots of animals but it is the first time that it has been found to match the way that humans forage.
The Lévy walk pattern appears to be ubiquitous in animals, similar to the golden ratio, phi, which is a mathematical ratio that has been found to describe proportions in plants and animals throughout nature.
Now a study led by University of Arizona anthropologist David Raichlen has found it can be applied to the Hadza tribe in Tanzania.
‘Scientists have been interested in characterising how animals search for a long time, so we decided to look at whether human hunter-gatherers use similar patterns,’ said Professor Raichlen.
The Hadza tribe is one of the last groups on Earth to still forage on foot with traditional methods and Professor Raichen said: ‘If you want to understand human hunter-gatherer movement, you have to work with a group like the Hadza’.
For the experiment, members of the tribe wore wristwatches with GPS units that tracked their movement while on hunting trips.
The GPS data showed that while the Hadza use other movement patterns, the dominant theme of their foraging movements is a Lévy walk – the same pattern used by many other animals when hunting or foraging.
The Lévy walk involves a series of short movements in one area and then a longer trek to another area.
Brian Wood, an anthropologist at Yale University who has worked with the Hadza people since 2004 and co-author of the study, said: ‘Detecting this pattern among the Hadza, as has been found in several other species, tells us that such patterns are likely the result of general foraging strategies that many species adopt, across a wide variety of contexts.’
Describing human movement patterns could help anthropologists understand how humans transported raw materials in the past.
Professor Raichlen said: ‘We can characterise these movement patterns across different human environments and that means we can use this movement pattern to understand past mobility.’
Adam Gordon, another co-author of the study and a physical anthropologist at the University of Albany, State University of New York, explained that the mathematical pattern seems to occur across species and environments from the desert to cities.
‘It shows up all across the world in different species and links the way that we move around in the natural world. This suggests that it’s a fundamental pattern likely present in our evolutionary history’ he said.
The Lévy walk is not limited to searching for food. Studies have shown that humans sometimes follow a Lévy walk while ambling around an amusement park and it can be used for planning cities.
Professor Raichlen said that most people observe the Lévy walk pattern on a daily basis.
‘What do you do on a normal day? Go to work and come back, walk short distances around your house? Then every once in a while you take these long steps, on foot, bike, in a car or on a plane. We tend to take short steps in one area and then take longer strides to get to another area,’ he said.
The researchers hope to conduct further research to understand the reasons for using a Lévy walk and whether the pattern is determined by the distribution of resources in the environment.
Herman Pontzer, a member of the research team and an anthropologist at Hunter College in New York, said: ‘We’re very interested in studying why the Hadza use this pattern, what’s driving their hunting strategies and when they use this pattern versus another pattern.’
Professor Wood said: ‘We’d really like to know how and why specific environmental conditions or individual traits influence movement patterns.’
The study was published in in the Proceedings of the National Academy of Sciences.
Originally published by the Daily Mail