Hunting in savanna-like landscapes may have poured jet fuel on brain
evolution
Rife with obstacles and occlusions, terrestrial environments potentially helped give rise to planning circuits in the brain

Date:
June 16, 2020
Source:
Northwestern University
Summary:
Compared to the vast emptiness of open water, land is rife with
obstacles and occlusions. By providing prey with spaces to hide
and predators with cover for sneak attacks, the habitats possible
on land may have helped give rise to planning strategies -- rather
than those based on habit - - for many of those animals.



FULL STORY ========================================================================== [African savanna (stock | Credit: (c) Grispb / stock.adobe.com] African
savanna (stock image).

Credit: (c) Grispb / stock.adobe.com [African savanna (stock | Credit:
(c) Grispb / stock.adobe.com] African savanna (stock image).

Credit: (c) Grispb / stock.adobe.com Close Ever wonder how land animals
like humans evolved to become smarter than their aquatic ancestors? You
can thank the ground you walk on.


========================================================================== Northwestern University researchers recently discovered that complex
landscapes -- dotted with trees, bushes, boulders and knolls -- might
have helped land- dwelling animals evolve higher intelligence than their aquatic ancestors.

Compared to the vast emptiness of open water, land is rife with obstacles
and occlusions. By providing prey with spaces to hide and predators with
cover for sneak attacks, the habitats possible on land may have helped
give rise to planning strategies -- rather than those based on habit --
for many of those animals.

But the researchers found that planning did not give our ancestors the
upper hand in all landscapes. The researchers' simulations show there
is a Goldilocks level of barriers -- not too few and not too many --
to a predator's perception, in which the advantage of planning really
shines. In simple landscapes like open ground or packed landscapes like
dense jungle, there was no advantage.

"All animals -- on land or in water -- had the same amount of time
to evolve, so why do land animals have most of the smarts?" asked Northwestern's Malcolm MacIver, who led the study. "Our work shows
that it's not just about what's in the head but also about what's in
the environment." And, no, dolphins and whales do not fall into the
category of less intelligent sea creatures. Both are land mammals that
recently (evolutionarily speaking) returned to water.



==========================================================================
The paper will be published June 16 in the journal Nature Communications.

It is the latest in a series of studies conducted by MacIver that
advance a theory of how land animals evolved the ability to plan. In a follow-up study now underway with Dan Dombeck, a professor of neurobiology
at Northwestern, MacIver will put the predictions generated by this computational study to the test through experiments with small animals
in a robotic reconfigurable environment.

MacIver is a professor of biomedical and mechanical engineering in Northwestern's McCormick School of Engineering and a professor of
neurobiology in the Weinberg College of Arts and Sciences. Ugurcan Mugan,
a Ph.D. candidate in MacIver's laboratory, is the paper's first author.

Simulating survival In previous work, MacIver showed that when animals
started invading land 385 million years ago, they gained the ability to
see around a hundred times farther than they could in water. MacIver hypothesized that being a predator or a prey in the context of being
able to see so much farther might require more brain power than hunting
through empty, open water. However, the supercomputer simulations
for the new study (35 years of calculations on a single PC) revealed
that although seeing farther is necessary to advantage planning, it's
not sufficient. Instead, only a combination of long-range vision and
landscapes with a mix of open areas and more densely vegetated zones
resulted in a clear win for planning.



==========================================================================
"We speculated that moving onto land poured jet fuel on the evolution
of the brain as it may have advantaged the hardest cognitive operation
there is: Envisioning the future," MacIver said. "It could explain why we
can go out for seafood, but seafood can't go out for us." To test this hypothesis, MacIver and his team developed computational simulations to
test the survival rates of prey being actively hunted by a predator under
two different decision-making strategies: Habit-based (automatic, such
as entering a password that you have memorized) and plan-based (imagining several scenarios and selecting the best one). The team created a simple,
open world without visual barriers to simulate an aquatic world. Then,
they added objects of varying densities to simulate land.

Survival of the smartest "When defining complex cognition, we made
a distinction between habit-based action and planning," MacIver
said. "The important thing about habit is that it is inflexible and
outcome independent. That's why you keep entering your old password for
a while after changing it. In planning, you have to imagine different
futures and choose the best potential outcome." In the simple aquatic
and terrestrial environments examined in the study, survival rate was
low both for prey that used habit-based actions and those that had the capability to plan. The same was true of highly packed environments,
such as coral reefs and dense rainforests.

"In those simple open or highly packed environments, there is no benefit
to planning," MacIver said. "In the open aquatic environments, you just
need to run in the opposite direction and hope for the best. While in
the highly packed environments, there are only a few paths to take,
and you are not able to strategize because you can't see far. In these environments, we found that planning does not improve your chances
of survival." The Goldilocks landscape When patches of vegetation and topography are interspersed with wide open areas similar to a savanna,
however, simulations showed that planning results in a huge survival
payoff compared to habit-based movements. Because planning increases
the chance of survival, evolution would have selected for the brain
circuitry that allowed animals to imagine future scenarios, evaluate
them and then enact one.

"With patchy landscapes, there is an interplay of transparent and opaque regions of space and long-range vision, which means that your movement
can hide or reveal your presence to an adversary," MacIver said. "Terra
firma becomes a chess board. With every movement, you have a chance to
unfurl a strategy.

"Interestingly," he noted, "when we split off from life in the trees
with chimpanzees nearly seven million years ago and quickly quadrupled
in brain size, paleoecology studies point to our having invaded patchy landscapes, similar to those our study highlights, as giving the biggest
payoff for strategic thinking." The study, "Spatial planning with long
visual range benefits escape from visual predators in complex naturalistic environments," was supported by the National Science Foundation Brain Initiative (award number ECCS-1835389).


========================================================================== Story Source: Materials provided by Northwestern_University. Original
written by Amanda Morris. Note: Content may be edited for style and
length.


========================================================================== Related Multimedia:
* YouTube_video:_Prehistoric_clutter_might_have_made_us_smarter ========================================================================== Journal Reference:
1. Ugurcan Mugan, Malcolm A. MacIver. Spatial planning with long visual
range benefits escape from visual predators in complex
naturalistic environments. Nature Communications, 2020; 11 (1)
DOI: 10.1038/s41467- 020-16102-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200616083408.htm

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