The Lévy Walk, How many creatures scam up meals...

August 28, 2017 8:37 AM

If you find yourself wandering, foraging, sightseeing, join the crowd South African Bushmen lived, (and some still do,) of a seventeen hour work week, spent in a walking pattern called the Levy Walk. Named after French mathematician Paul Levy, a Levy Walk is characterized by many small moves combined with a few longer trajectories. Evidence of Lévy walks has been found in the way humans wander University Campuses, urban areas, and Disney world. Here is a more detailed Here is the scholarly discussion of the flight of fireflies.

This initial article discusses how humans search for anything. Using data from observation, and GPS attached to modern hunter / gatherers, scientists, search to understand how we lived on this world in more ancient times, and with more simple means. The implication is the hunter / gatherers of South Africa had it pretty good, before the colonialists changed their lives, and before agriculture. The film The Gods Must Be Crazy comically covers the arrival of civilization in the life of a Bushman, when a coke bottle falls from a passing plane.

posted by Oyéah (26 comments total)

Isn't this just a scholarly term for "go to a cluster of food/goods, (oasis, patch of berries, root vegetables, herd of animals) and exploit it until you no longer can, then move to another"?

Plants grow and spread in clusters, cluster around water sources, etc. Same with animals.
posted by jeff-o-matic at 10:13 AM on August 28, 2017 [4 favorites]

Surely this is useful for separating out civilians from combatants.
posted by Oyéah at 12:41 PM on August 28, 2017 [1 favorite]

This is how I look for my car keys.
posted by cardboard at 1:03 PM on August 28, 2017 [9 favorites]

“The Hadza move around a great deal. It’s astounding,” said Brian Wood, the study’s author, an anthropologist at Yale University.

For instance, the men walked more than 11 km per day on average.

Huh... I'm fascinated to learn that apparently a) I often walk more than a professional hunter-gatherer in a day, if you count my daily commute + some extra just for fun (ie pokemon) and b) walking for ~2h per day is an "astounding" amount.

I guess they'd walk much slower during the "many small moves" part, though, what with the gathering and all.
posted by randomnity at 1:40 PM on August 28, 2017 [3 favorites]

This is neat.

But also, that large events (or excursions) are rare, and small events (or excursions) are common, and that there's a continuous power-law distribution connecting them seems so universal, the really surprising part to me is that there are real biological search patterns that don't have such properties.
posted by eotvos at 1:47 PM on August 28, 2017 [1 favorite]

I sat at a picnic table eating ice cream yesterday with my wife and annoyed her by describing the flight pattern of a flock of pigeons I watched over her shoulder. I couldn't understand why they seemed to turn at random in a tight area then turn again, fly a little distance away, repeat the tight patterns, then fly, seemingly at random, off in another direction. I wondered aloud about whether it was peculiar to these specific pigeons, or to all pigeons. I never imagined that, like a conspiracy in a film thriller, the implications were much larger.
posted by putzface_dickman at 6:18 PM on August 28, 2017 [1 favorite]

I always love learning that some everyday phenomenon has a theory and a nomenclature. This one's really useful. But I'm also scratching my head over the gee-whiz tone of it. 11km is just 6.8 miles, or like 14,000 steps, which, thanks to my FitBit, I know I clear every day. And my walking patterns would probably fit the general structure too, though I'm not mostly looking for food (well, a little) - but, like, I walk around the house (short trajectories) then go to work (long trajectory), then walk around work and get lunch and do errands (short trajectories), then return home or go out (long trajectory) and make short movements around there. It doesn't seem food-driven so much as human-body-driven behavior.

Also, any traveler will recognize it - drive on the high-speed highway for some length of time, stop, get out of the car, and meander around a much smaller area.
posted by Miko at 6:49 PM on August 28, 2017 [1 favorite]

Isn't this just a scholarly term for "go to a cluster of food/goods, (oasis, patch of berries, root vegetables, herd of animals) and exploit it until you no longer can, then move to another"?

No.

"Go to" isn't an adequate description for many forager/resource pairs -- often the forager can't tell from one patch where or how good the other patches are. "Exploit it until you no longer can" is likely to be lethally inefficient; "exploit it until the advantage of combing the nearly-exhausted local resources is lower than the probable advantage of striking out for new ones" is a lot more complicated. Especially since some organisms doing this have minimal or no memory, which changes the expected payoffs hugely, so the walk algorithms can be vitally different -- see the "detailed" link. And finally, not all resources, plants or animals, grow in clumps; some of them are spaced to avoid resource competition, or disease, or because something else came through and foraged them less than a full generation ago, or because the reproductive process requires it, etc etc. The spacing-out can be random or regular, depending on the controlling process (or autocorrelated or biassed by, say, seasonal wind direction). Cf. point processes.

Which there's no reason for you to be a scholar of, but following any link other than the movie should have tipped you off that foraging isn't "just" obvious. Even the movie, actually; neither the Bush nor the industrial life is obvious, which we can see when we see them from the other side.
posted by clew at 7:41 PM on August 28, 2017 [4 favorites]

There's a buried assumption here, that the environment is homogeneous, that known places where one last was successful in hunting for food don't exist.

This is contrary to my own personal experience, where there have been many successful meals had at various commercial establishments around my home.... to someone from outer space unaware of these, it might look like a Levy walk... but to me, it's just a trip to McDonalds for food, and Speedway for gas.

I suspect the same is true for any competent hunter/gatherer.
posted by MikeWarot at 7:49 PM on August 28, 2017 [2 favorites]

"The implication is the hunter / gatherers of South Africa had it pretty good, before the colonialists changed their lives, and before agriculture."

And the wonderful cultural, technological, and historical works created by such subsistence lifestyle have shaped history. Oh, wait...

Life without culture is short, nasty and brutish.
posted by NeoRothbardian at 8:15 PM on August 28, 2017

The Washington Post had an article about this today, but I opted to copy in the article from another source. The implication is that their lives were not short, nasty or brutish. They treasure one another, they know their territory, and they use it well, do not devastate it, because that means they are devastated. I have see films of the Bushmen and the lives of others who hunt and gather, I was struck by the laughter.

Included in the Lévy Walk was Disneyland, or (I bet,) market shopping, like street market shopping. I am not a fan of those history shapers, of the first order, you know, the "so and so the greats," the Napoleons, any of them, actually. Many artworks come from the hunters and gathers, and early farmers. Little statues, giant caves full of paintings of the creatures of the day, how ever long ago they Lévy walked, the aurochs, the horses, the birds, the hand prints of the Lévy walkers.
posted by Oyéah at 9:31 PM on August 28, 2017 [2 favorites]

Life without culture is short, nasty and brutish.

If you mean agriculture, then no - apart from infant mortality (which is also high for most agricultural societies until very recently) life expectancy and quality of life was usually higher for hunter-gatherers.

If you mean culture, then yes, but hunter-gatherers tend to have an awful lot of culture.

Hobbes wasn't much of an anthropologist, TBH.
posted by BinaryApe at 12:57 AM on August 29, 2017 [8 favorites]

If you asked me to accept a 100% random assignment to another human life anywhere on Earth, and gave me the choice between now and about 15,000 years ago, I'm honestly not sure what I'd go with. (Sure, MY present day life is rad, but I'm one of the luckiest people alive to have access to the rights and medical technology that I do.)
posted by showbiz_liz at 4:18 AM on August 29, 2017

If you mean culture, then yes, but hunter-gatherers tend to have an awful lot of culture.

No, no. they obviously meant The Culture. As in Fully Automated Gay Space Luxury Communism.
posted by mikelieman at 5:51 AM on August 29, 2017 [1 favorite]

Also, Dude, Bushman is not the preferred nomenclature.
posted by thelonius at 7:09 AM on August 29, 2017

It seems really really likely that modern urban human behavior and ancient hunter-gatherer behavior aren't that far apart.
posted by Miko at 8:31 PM on August 29, 2017

It seems transparently obvious to me that modern urban behavior and hunter-gatherer behavior are wildly different, because I would have to learn so much to survive as a hunter-gatherer. That we have the same potential behaviors, sure, all being modern Homo sap., and some urban problems are more like hunting-gathering than others*, but three millennia of techne have done a lot.

Wandering through Disneyland, college campuses, and other parks: hunting-gathering-like. Traveling between home, work, and a restaurant and grocery store: not hunting-gathering. What's one way to tell? Well, the former have the same statistical model as Levy walks and the latter doesn't.

Abstract of a study of intermediate cases, of animals who have some memory and some building capacity.
posted by clew at 2:57 PM on August 30, 2017

obvious to me that modern urban behavior and hunter-gatherer behavior are wildly different, because I would have to learn so much to survive as a hunter-gatherer

Not learning. I'm not talking about cognition, I'm talking about a bent toward behavior that was selected for long before modern life rapidly and recently imposed its conditions.

the former have the same statistical model as Levy walks and the latter doesn't

Only because we've introduced externally powered transporation, which has lengthened and diverted those trajectories. Which is mainly just an issue of scale.
posted by Miko at 10:33 AM on August 31, 2017

NeoRothbardian: And the wonderful cultural, technological, and historical works created by such subsistence lifestyle have shaped history. Oh, wait...

Life without culture is short, nasty and brutish.

There are living people who grew up in a hunter-gatherer culture and only encountered outsiders as adults. In the case of the Pintupi Nine, a number of them have extremely successful art careers *because* they came from such a rich culture. And those were people living in some of the most extreme and difficult hunter-gatherer conditions. Those living in more normally rich environments had immense amounts of leisure time, which they filled up with stories, art and all the complexity humans are capable of.
posted by tavella at 11:08 AM on August 31, 2017 [3 favorites]

the former have the same statistical model as Levy walks and the latter doesn't

Only because we've introduced externally powered transporation, which has lengthened and diverted those trajectories. Which is mainly just an issue of scale.

No. Levy walks are scale invariant.
posted by clew at 11:22 AM on August 31, 2017

Problem of definition. Artifact of modernity. Bias in theory.
posted by Miko at 7:26 PM on August 31, 2017

There are animal-environment pairs in which the animals' paths are Levy walks; in some of those the animals are humans; in some of them the environment is built. And likewise there are animal-environment pairs in which the animals' paths are not Levy walks, because lots of "wandering around foraging" paths are not Levy walks. And these cases also include all four of human or not human animal, and built environment or not-built. So what part of "definition, modernity, theory" falls down in which of the eight categories?
posted by clew at 7:41 PM on August 31, 2017

What environments are in the pairs?
posted by Miko at 6:06 AM on September 1, 2017

The impact of scale is what I meant by artifact of modernity. I just read a handful of levy-walk articles, and they seem to indicate that levy walk behavior is independent of scale.
posted by Miko at 6:14 AM on September 1, 2017

Going out of order: yes, you can't satisfy Levy walk definitions and be scale-dependent. That's why "we can move farther because sidewalks and cars" cannot explain why, for-instance, the location series our cellphones learn that tell them when we're getting food *aren't* Levy walks, but the movement habits of a particular society of hunter-gatherers when getting food *are* Levy walks.

So that's same organism, different environments, different movement statistics. We can ask humans and verify that they intended to get dinner in both cases, but the observable behavior is different because the environment is different.

Tell me what you've been reading? There's so much current debate over how widely Levy walks occur, let alone why they might occur, that I can't guess what would come up first.

Another pair: underground rodents in high- or low-productivity environments, eg pocket gophers in alfalfa fields in California, vs naked mole rats in their native deserts. Probably non-foraging behavior determines pocket gopher tunnel construction, because they can find plenty of food so they spend more work on mating competition and avoiding snakes. Not Levy. But the main problem for naked mole rats is finding resources that are highly localized in both space and time, so lots of their work is foraging without being able to know where they should go, so more Levy-like. Now, these are not closely related rodents, and everything else in their lifecycle has also been adapted to richness vs scarcity, so they aren't the same organism. It's just difficult to find literally the same organism in radically different wild environments, and fossorial rodents are really cool share a lot of adaptations to going underground.

(Maybe rats are same-organism, different-environments -- on superficial searching, possibly Levy explorers in the wild, memory-based in cities? )
posted by clew at 11:34 AM on September 1, 2017

** Footnote! When we're flaneusing in a new environment, our cellphones might see Levy walks, that's probably the point of the Disney and campus evidence. But the great mass of workday behavior is way predictable.
posted by clew at 11:36 AM on September 1, 2017