Perfection: The Enemy of Evolution
Freedom to miss the optimal mark opens a wide range of new designs over
time

Date:
May 18, 2023
Source:
Duke University
Summary:
Evolution is a sequence of design changes happening on their own in
a discernible direction; it never weds itself to a single point on
a drawing board. An evolving system or animal is free to simply go
with what works. Not so much that its performance suffers greatly,
but enough that it opens access to other options near the so-called
optimal design.

With scientists often looking to nature for clues to solve
challenges, they should also free to miss the optimal mark and
open a wider design space over time.


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==========================================================================
FULL STORY ========================================================================== Scientists are often trained to seek out the absolute best solution to a
given problem. On a chalk board, this might look something like drawing
a graph to find a function's minimum or maximum point. When designing a turbojet engine, it might mean tweaking the rotor blades' angles a tiny
degree to achieve a tenth of a percent increase in efficiency.

Adrian Bejan, the J.A. Jones Distinguished Professor of Mechanical
Engineering at Duke University, was busy demonstrating the former for a
class full of students when a thought struck him: this is not how nature operates. Evolution is a sequence of design changes happening on their
own in a discernible direction; it never weds itself to a single point on
a drawing board. An evolving system or animal is free to simply go with
what works. Not so much that its performance suffers greatly, but enough
that it opens access to other options near the so-called optimal design.

With science often looking to nature for clues to solve challenges, Bejan wondered if he might look the opposite way, to predict nature before
looking at it. If problem solvers and builders were free to miss the
absolute highest mark, how much greater might be the range of designs they consider plausible? That's the question that Bejan posits in a new paper published online May 16 in the journal Biosystems. Using two relatively
simple examples -- walkways ferrying passengers off a train and a bird
flapping its wings -- he discovers that the answer is, "quite a lot."
"In engineering, design, theater, architecture or even the organization
of this university, any form of design benefits from the ability to make
good but imperfect decisions and the freedom to move on and contemplate
other opportunities for improvement," Bejan said. "If one is wedded
to the idea of the absolute best, nothing new will ever be created."
In the paper, Bejan first looks at the example of passengers arriving
by train and walking across a room with many exit points. With the total
area of the room remaining constant but the length and width of the room
free to change, he solves for the optimal shape of the room to get all passengers where they're going the quickest. With the solution equations
in hand, he shows that providing even 1% wiggle room for imperfection
away from the best performance opens the design space by 28%.

In his second example, Bejan looks at the flapping motion of birds
at nearly constant altitude and speed. Considering the various forces
involved -- drag during gliding, lift created by wing size, speed and
body size, among others - - he formulates an equation for the rhythm of
wings needed to maintain constant speed with minimum effort. While an
optimal answer does exist, Bejan once again shows that allowing for just
1% imperfection above the theoretical minimum effort opens the design
space by 20%.

Bejan says that he chose these examples because they involved changing
only a single variable, a single degree of freedom -- the shape for a
room or the flapping rhythm for a wing. In more complex examples that
involve many variables, these tiny tolerances for imperfection create
an even wider range of "good enough" solutions.

The lesson learned is that science now has a predictive idea of how
nature works. By focusing less on finding absolute optimal designs,
researchers may use the freedom to iteratively move toward entirely new
design concepts that wouldn't otherwise have been within their sight. It
also gives designs, methods and entire fields of study the ability to
adapt to a changing world.

"The doctrine of chasing the best design is not helpful," Bejan said. "The teaching of science should go hand-in-hand with the freedom to take a
shot, hit the vicinity of the mark and move on. The end goal isn't just
to hit a bullseye, but to keep more arrows in your quiver to keep taking
shots over a long period of time." This work was supported by a grant
from CaptiveAire Systems.

* RELATED_TOPICS
o Plants_&_Animals
# Evolutionary_Biology # Birds # Nature
o Earth_&_Climate
# Sustainability # Earth_Science # Weather
o Fossils_&_Ruins
# Evolution # Human_Evolution # Early_Birds
* RELATED_TERMS
o Hurricane_proof_building o Earth_science
o Rotifer o Ionosphere o Weather_forecasting o
The_evolution_of_human_intelligence o Convergent_evolution
o Parallel_evolution

========================================================================== Story Source: Materials provided by Duke_University. Original written
by Ken Kingery. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Adrian Bejan. Perfection is the enemy of evolution. Biosystems,
2023;
229: 104917 DOI: 10.1016/j.biosystems.2023.104917 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230518172034.htm

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