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The title of this talk
is "The Evolutionary Web of Life."
My name is John Torday.
I'm a Professor of
Pediatrics and Obstetrics
and I also am in the
Evolutionary Medicine Program
at University of
California-Los Angeles.
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The rationale for
this presentation is
rather unconventional in
that I'm using homeostasis
as the selection
pressure for evolution.
So I'm going to go
through that rationale.
Homeostasis is the mechanistic
basis for physiology.
Homeostasis be traced all the way
back to unicellular organisms.
Unicellular organisms are
the bauplan, or the blueprint
for metazoans, or
multicellular organisms.
And homeostasis is a mechanism
for monitoring of the environment,
both internal, that is,
physiology, and external,
which is the physical environment.
Homeostatic set-points
can be changed
through cellular-molecular
remodeling,
providing a mechanism for
structural/functional change
in adaptation to the environment.
Or, as we recognize it, evolution.
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So a historic perspective is of use
here for this homeostatic approach.
The concept of homeostasis
was first formulated
by Claude Bernard
in the 19th Century.
And then, a term was coined by
Walter Canon in the 20th Century.
Homeostasis is not part of the
evolutionary biology domain
per se, but probably because it
was focused on fossilized material
as the ultimate evidence
for its relevance.
The agents that mediate homeostasis
do not fossilize, though it may be
argued that their
remains are embedded
in molecular structure and function.
For example, Conrad Bloch,
the discoverer of cholesterol
synthesis, reasoned that since it
took 6 oxygen molecules to generate
1 cholesterol molecule,
that cholesterol
was actually a molecular fossil.
We've extended that
concept by reducing
complex physiologic principles
to molecular phenotypes,
and then reverse-engineered
their evolutionary history
using their ontogeny, phylogeny,
and pathophysiology as algorithms
to understand their forward
and reverse histories.
