Evolution:
Offbeat Observations
Georg
Lichtenberg said “It is impossible to carry the torch of truth through a crowd
without singeing someone’s beard”, according to James Geary (2005, The World in a Phrase, Bloombury
Publishing, New York, 229 pp.). It
somewhat comforts me as I write about the multiple errors earnest and
intelligent researchers of evolution have made, errors I am trying to replace
with a more accurate depiction of the tree of life.
One, of the
two worst research reports establishing a faulty superphylum, Ecdysozoa, had a
lady as the primary author; it made me realize the sexist nature of the
aphorism quoted above. I also do not
know if the gentleman first author of the publication setting up the other
faulty superphylum, Lophotrochozoa, had a beard to be singed.
The most
influential zoologist of the last hundred years could well be Libbie
Hyman. See http://evolutioninsights.blogspot.com/2015/03/abandoned-theories-and-libbie-hyman.html
She deserves the respect given her, mistakes in her work are minimal,
and I also do not want to detract from other work by the two authors whose work
is criticized in http://evolutioninsights.blogspot.com/2013/05/science-screw-up-no-1.html , after all, “to err is human”. I guess that proves I am human too.
When offbeat
becomes main-stream evolution
Three of the
last four blog posts have had bits about the abyssal ocean. There are several facts about the abyss that
can help us understand major consequences for evolution shaping life today in
unappreciated but interconnected ways.
One, the
stability of the abyssal region offered refuge from numerous early extinction
events.
The extreme
pressure, lack of light for photosynthesis, low input of surface debris
reaching the abyss, near-freezing temperature, and sparse populations were
ecological factors leading to the long-life, low reproductive rates, and emphasis
on survival adaptations characteristic of K-selected
life styles. They contrast to r-selected life styles of organisms where
abundant food and high predation lead to short lives, high reproductive rates,
rapid growth, and perhaps higher evolutionary rates of most organisms in
lighted, warmer surface habitats.
Two, the abyssal affects on embryology and metabolic rates
The low
reproductive potential in the deep sea put such a high priority on survival
that it selected for delayed specification of embryonic fate of cells so loss
of a cell from an early embryo would not prevent normal development. This led the transition from protostomes to
deuterostomes that have the ability to have an early embryo divide and produce
two individuals instead of dying like a protostome embryo would. Pogonophorans are at the junction where this
happened and they have a mix of protostome and deuterostome features.
As I have
noted elsewhere, the extreme pressure is probably a factor slowing metabolic
rates and extending life-spans in the abyss.
Several studies have shown respiration is slowed greatly beyond what
colder temperatures alone would depress rates.
One of the most enlightening clues was that a brown bag lunch contained
a sandwich and an apple, that sank to the ocean bottom many months before they were retrieved with the sunken research vessel, Alvin, and were both in fresh condition. Similar food in cold seawater decayed within
a few days.
The ocean
layer and circulation patterns described in a recent blog show that oxygen
levels below the oxygen minimum layer would be impossible to exist if respiratory
rates at abyssal pressures were anywhere near rates normal in shallow water
below the photic zone.
Three, it’s
a bit complicated,
but the things above help show the role of the pogonophorans
as an intermediate that also accounts for some features of our development and
structure that were first accounted for by the annelid theory of chordate
origin, an abandoned theory that is correct when adjusted for the role of the
pogonophorans.
Joseph
Engemann Emeritus Professor of
Biology, Western Michigan University, Kalamazoo, Michigan September 30, 2017
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