
Random Search Wired into Animals May Help Them Hunt - pseudolus
https://www.quantamagazine.org/random-search-wired-into-animals-may-help-them-hunt-20200611/
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bschne
In „The Secret of Our Success“ (aside: everytime I write that title I cringe a
little at how self-help-y it sounds), Joseph Henrich conjectures that human
divination rituals might have evolved as a way to randomize hunting behavior
so as not to become predictable to the animals being hunted for. Not sure how
plausible to find it, but I found the thought pretty intriguing.

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alexpotato
Not sure if this is from the same book but I've heard something similar about
"lunacy" being linked to the full moon.

The reason there is more crime and wild behavior during a full moon is not
because of any gravitational effects of the moon etc. Rather, we are descended
from tribal peoples who celebrated the full moon with wild parties. Said
parties led to intercourse which led to children etc.

Not sure how valid that is but I've always liked the idea.

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benrbray
Isn't a simpler explanation that it's brighter at night during a full moon,
making it easier for opportunistic nighttime shenanigans?

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alexpotato
Thank you for explaining this more simply!

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barrkel
This is interesting from an optimization perspective too.

The intermittent big jumps are what you need to get out of local optima. You
can use gradient ascent locally, but once you stop improving, a big change is
needed.

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reedwolf
Note:

>Ironically, their paper arrived only months after a study co-authored by
Viswanathan, da Luz and Raposo showed a catastrophic error in Viswanathan’s
original albatross study. The wet/dry sensors they had relied on weren’t dry
only when the birds flew: They were also dry when the albatrosses sat on their
nests. Some of the longest “flights” in the data set might have actually been
protracted visits to the birds’ nests. The study also criticized certain
analytical techniques and claimed that albatrosses don’t do Lévy walks after
all, and that it was unclear whether many species did.

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vlovich123
The answer is immediately in the paragraphs following.

> Sims acknowledges that the conflicting papers “put people on edge.” But his
> work used more up-to-date mathematical methods to demonstrate that a whole
> menagerie of marine predators take Lévy walks.

> These improved methods quashed doubts over whether animals ever do Lévy
> walks. “The amount of data is overwhelming,” said da Luz.

> Sims and Humphries even revisited albatrosses in a subsequent study in 2012.
> Working with more sophisticated GPS tracking devices, they found that
> albatrosses did not perform Lévy walks while searching for food above
> shallow water, where they might have more visual or olfactory information to
> guide them. But when they flew out over deeper water, the birds did in fact
> adopt Lévy searches.

So the original work had the right conclusion (Albatrosses do adopt Levy
searches) for totally flawed reasons (the data didn't actually support the
conclusion, the Levy walks weren't being used for the time periods originally
predicted).

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FakeRemore
Considering the variety of animals that seem to show this behavior, isn't it
possible that mammals, specifically humans, are "encoded" with that same
random search pattern? I'm not sure how you'd test for it though.

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SubiculumCode
I instantly thought about eye tracking experiments, in which we see lots of
small movements around an area, then big jumps across the screen. I guess
others have thought about it too.

[https://journals.aps.org/pre/abstract/10.1103/PhysRevE.79.05...](https://journals.aps.org/pre/abstract/10.1103/PhysRevE.79.056114)

[https://www.academia.edu/1112368/Modelling_gaze_shift_as_a_c...](https://www.academia.edu/1112368/Modelling_gaze_shift_as_a_constrained_random_walk)

I'm intrigued.

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FakeRemore
> Specifically, we use comparisons of maximum-likelihood fit as well as
> standard deviation analysis and diffusion entropy analysis to show that
> visual search during language comprehension exhibits Lévy-like rather than
> Gaussian diffusion.

That is _fascinating_. Thanks for that.

> However, one could argue, from an evolutionary standpoint, that spe-ciÿc
> search mechanisms could have been learned and “wired” in order to improve
> theexploration eciency (e.g., if a salient point is located within a direct
> vision distance,maximize the probability of straightforwardly moving to that
> site)

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dr-ando
Relatedly, a paper was posted to bioRxiv a few days ago describing the results
of large scale fruit fly release-and-recapture experiments. They conclude the
abstract with "Our field data do not support a Lévy flight model of dispersal,
despite the fact that our experimental conditions almost perfectly match the
core assumptions of that theory."

[https://www.biorxiv.org/content/10.1101/2020.06.10.145169v1](https://www.biorxiv.org/content/10.1101/2020.06.10.145169v1)

Also, Viswanathan's 1996 Nature paper was stupendously wrong due to the key
measurements being in error, but instead of retracting it, he and colleagues
published a followup - in Nature 2007 - in which they say the albatross flight
times are gamma distributed.

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dsrmar
Is it possible that it's actually scarce resources are randomly allocated via
power law distributions and that the search isn't what's random?

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FartyMcFarter
The article covers this. Fruit flies still did Levi walks when not able to
sense anything.

