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| Choanoflagellate colony stained to highlight DNA and other features (Nicole King lab) |
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| Mono Lake’s extreme environment, characterized by high salinity and toxic substances such as arsenic and cyanide, may have driven the evolution of this distinctive species. |
.California discovery may explain evolutionary arising of animals
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| Microscopic choanoflagellate B. monosierra |
(The Brighter Side of News)
Mono Lake, nestled in Northern California’s Eastern Sierra Nevada, is a haven for unique life forms [as it fills with water washing down from
Yosemite National Park's
alpine lakes, most of which evaporates faster than it can be replenished].
Its iconic
tufa formations and thriving populations of brine shrimp (aka fly larvae) and alkali flies showcase an ecosystem adapted to the lake's hypersaline, alkaline waters.
- PHOTO: Globular colonies of the choanoflagellate Barroeca monosierra seen under a microscope. As indicated by the 50-micron scale bar in the upper left, these colonies are at the limit of what’s visible to the naked eye (Alain Garcia De Las Bayonas, Nicole King lab, © The Brighter Side of News).
Now, researchers from the
University of California at Berkeley have identified a microscopic organism in this extreme environment that could illuminate the early evolution of life.
The discovery is a single-celled organism called a
choanoflagellate, a group that holds special significance in the study of evolution.
Although not animals themselves,
choanoflagellates are the
closest known living relatives of animals.
Their biology offers vital clues about
the transition from single-celled to multicellular life. What sets this particular species apart is its
microbiome.
Unlike other choanoflagellates, which typically consume bacteria, this species forms a stable, physical association with its bacterial partners.
This makes it the simplest known organism to host a microbiome, providing researchers with an unprecedented opportunity to study how early interactions between single-celled organisms and bacteria influenced the evolution of complex life, including animals.
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| This could explain life. |
“Very little is known about choanoflagellates, and there are interesting biological phenomena that we can only gain insight into if we understand their ecology,” says
Nicole King, a professor of molecular and cell biology at UC Berkeley and an investigator for the Howard Hughes Medical Institute.
More- Ancient tribal protectors of Mono Lake: Kucadikadi ("shrimp eaters" or "fly people"), Northern Paiute of California
The Chicken or the Egg?
Which came first,
the chicken or the egg? It's very simple in reality. Only in theory it's impossible to answer because it's a
philosophical paradox or
causality dilemma. The conundrum is a kind of logical fallacy of getting caught up in categories, terminology, and semantics, losing sight of the fact that we as onlookers are the ones creating the arbitrary labels, determining the limits of categories, and making the subjective judgments to include somethings and exclude others.
- The dilemma stems from the observation that all chickens hatch from eggs and all chicken eggs are laid by chickens, a situation where it is not clear which of two events should be considered the cause and which should be considered the effect, to express a scenario of infinite regress, or to express the difficulty of sequencing actions where each seems to depend on others being done first.
Wittgenstein would be dismayed. The answer, of course, is the
proto-chicken, a creature which is a "chicken" because it lays chicken eggs but is not a chicken because it itself was not born of such an egg. Yet, if it looks like a chicken and clucks like a chicken, it is chicken enough because it does the most important thing, which is to give birth to chickens rather than it itself being born the way "chickens" are thereafter. (The exact same evolutionary question might be asked of
Homo sapiens or modern humans.
Which came first, the human or the womb? If all humans are born of wombs and all human wombs are produced [only] by humans, we're in the same dilemma. (Neither is completely true, but we begin with this assumption to our detriment).
The excellent thing about this discovery by UC Berkeley, my own alma mater, is that it gets at the reality and avoids the logical trap, causality dilemma, or infinite regress logicians would be caught in. There is a transitional creature that is neither yet fully animal nor solely pre-animal because it has a stable microbiome it has partnered with. Similarly, humans born of a womb and giving birth via a womb must have been preceded by a humanoid creature who did not do both.
Where did animals like us come from? That is the question at hand. If this is how "animals" behave and get defined (born of womb and birthing others via a womb), we will trap ourselves in assumptions and the rules of logic. Once we broaden the category to include the proto-animal, or in this case the choanoflagellate with a microbiome, we can begin to see how things might have gone through an intermediary phase not allowed for, assumed, or understood by our strict logic. So hooray for the transitional creature that yet remains alive to be studied that we might understand these animal bodies we identify with as and cling to as "self."
