Archive for the ‘Life’ Category

Life does not survive to reproduce; rather, it reproduces because survival must end

September 16, 2026

Introduction:

An off-shoot idea I have had for a long time is that the most primal characteristic of being alive seems to be the drive to survive and remain alive. This is probably even more primitive than the drive to reproduce which, I think, makes more sense as a risk mitigation action for the unavoidable risk of not surviving. This little essay expands on that theme.


I have come to realise that for living things (for life), it is survival which is primal and it is reproduction which follows only as a mitigation for the risk of mortality.

If we strip biology down to its first principles, traditional evolutionary theory asks us to accept a strange inversion: that reproduction is the ultimate engine of life, and survival is merely a clumsy mechanism organisms use to stick around long enough to pass on their genes. But when we examine the actual physics of living systems, this hierarchy reverses. The most primal, non-negotiable characteristic of life is not the drive to multiply. Instead, it is the fierce, unyielding drive to be, to remain intact. If a cell did not age and die of itself and, in principle, was immortal, reproduction would be both unnecessary and unsustainable.

Before a system can have the luxury of looking outward and indulging in replication, it must first establish an internal boundary against the relentless pull of not-being, of not surviving, of dying. This drive for continuing to be, for self-generation and self-maintenance is the core imperative of any living system. (The word autopoiesis was invented in the 1970s to describe this but I dislike its artificiality and do not see that it adds any great value). From single-celled bacteria avoiding or evading what they detect as chemical toxins, to complex organisms exhibiting flight or fight behaviour when faced by physical threat, the primary directive is always self-preservation. Living is always in hope, in the belief that even with the last breath that there is another breath to come. Life fights tooth and nail simply to continue to be. If any system lacked this primal will to maintain its own structural integrity against non-existence, it would dissolve before reproduction even entered the equation.

Why, then, does reproduction exist at all? If survival is the ultimate goal, a successful organism would logically lock into a permanent state of just necessary sufficiency, of bare self-preservation. Without inherent aging the organism would be immortal. Yet, every individual biological organism, without exception, is mortal. Empiricism tells us that immortality has never been observed. In the war against time and entropy and environmental friction, individual mortality is guaranteed and survival, inevitably and always, ends.

This is where the true nature of reproduction is revealed. It is not the primary goal, but actually a quite brilliant, insurance policy. It is mitigation for the risk of not surviving. Because an individual organism cannot permanently defeat dying, life invents replication as a structural workaround. It is a hedge against extinction where specific individuality is sacrificed. It is a mechanism which maintains a string of individuals but no single one. It employs the copying of software onto a fresh hardware drive because the original hardware will inevitably fail.

It is a masterpiece of elegance in that this insurance policy is dynamically tuned by a feedback loop between risk of imminent dying and reproductive output. Not for each individual but averaged across many individuals. If the chance of surviving another year is low, investing energy into long-term bodily maintenance (longevity) is a wasted bet. The insurance policy must pay out immediately. This is why small rodents or insects have short lifespans and massive, rapid litters. If the baseline survival rate is high, the “insurance policy” doesn’t need urgency or front-loading. The organism can afford to stick around, protect its investment, and nurture its offspring over a longer, more stable timeline. This is why large mammals, elephants, whales, and humans feature long lifespans and slow, deliberate reproduction. When an organism faces high extrinsic mortality, where harsh pressures make individual survival statistically unlikely, the system triggers an emergency response, accelerating reproduction and shortening focus at the expense of longevity. Conversely, when stable conditions allow for extended survival, life dials back reproduction, trading sheer volume for long-term somatic maintenance and quality control. The terms of the policy adapt, it seems, directly to the threat of not being.

My postulation is that reproduction comes downstream of survival. Framing reproduction as a risk-mitigation strategy allows us, I think, to change how we view the drivers of living systems. It moves us away, I believe, from a purely gene-centric utility model and instead, sets life in a deeper, more fundamental, existential struggle. It is the difference between living and being inert. Life is the aspiration of an organized system to continue to be against the void of non-existence. It is this aspiration manifested which – in my view –  we call the mystery that separates the living from the inert.

Life does not survive to reproduce; rather, it reproduces because it is certain that survival must end.


 

Life on land four times older than previously thought

July 23, 2013

“Settled science” has had it that life on land dates from about 500 million years ago. But fossils of something rather simpler than plants or animals found in South Africa provide evidence that life on land could be 2.2 billion years old.

Gregory J. Retallack, Evelyn S. Krull, Glenn D. Thackray, Dula Parkinson. Problematic urn-shaped fossils from a Paleoproterozoic (2.2Ga) paleosol in South Africa. Precambrian Research, 2013; 235: 71

DOI:10.1016/j.precamres.2013.05.015

Science Daily: 

Conventional scientific wisdom has it that plants and other creatures have only lived on land for about 500 million years, and that landscapes of the early Earth were as barren as Mars.

A new study, led by geologist Gregory J. Retallack of the University of Oregon, now has presented evidence for life on land that is four times as old — at 2.2 billion years ago and almost half way back to the inception of the planet.

That evidence, which is detailed in the September issue of the journal Precambrian Research, involves fossils the size of match heads and connected into bunches by threads in the surface of an ancient soil from South Africa. They have been named Diskagma buttonii, meaning “disc-shaped fragments of Andy Button,” but it is unsure what the fossils were, the authors say.

“They certainly were not plants or animals, but something rather more simple,” said Retallack, professor of geological sciences and co-director of paleontological collections at the UO’s Museum of Natural and Cultural History. The fossils, he added, most resemble modern soil organisms called Geosiphon, a fungus with a central cavity filled with symbiotic cyanobacteria.

“There is independent evidence for cyanobacteria, but not fungi, of the same geological age, and these new fossils set a new and earlier benchmark for the greening of the land,” he said. “This gains added significance because fossil soils hosting the fossils have long been taken as evidence for a marked rise in the amount of oxygen in the atmosphere at about 2.4 billion to 2.2 billion years ago, widely called the Great Oxidation Event.”

By modern standards, in which Earth’s air is now 21 percent oxygen, this early rise was modest, to about 5 percent oxygen, but it represented a rise from vanishingly low oxygen levels earlier in geological time. …

Read the whole article

Tenacious life: Microbe swaps phosphorous for arsenic

December 2, 2010
Lakeside of the Mono Lake with Tufa columns in...

Mono Lake: Image via Wikipedia

The New York Times has the story that has been buzzing all day:

Scientists said Thursday that they had trained a bacterium to eat and grow on a diet of arsenic, in place of phosphorus — one of six elements considered essential for life — opening up the possibility that organisms could exist elsewhere in the universe or even here on Earth using biochemical powers we have not yet dared to dream about.

The bacterium, scraped from the bottom of Mono Lake in California and grown for months in a lab mixture containing arsenic, gradually swapped out atoms of phosphorus in its little body for atoms of arsenic.

Scientists said the results, if confirmed, would expand the notion of what life could be and where it could be. “There is basic mystery, when you look at life,” said Dimitar Sasselov, an astronomer at the Harvard-Smithsonian Center for Astrophysics and director of an institute on the origins of life there, who was not involved in the work. “Nature only uses a restrictive set of molecules and chemical reactions out of many thousands available. This is our first glimmer that maybe there are other options.”

Felisa Wolfe-Simon, a NASA astrobiology fellow at the United States Geological Survey in Menlo Park, Calif., who led the experiment, said, “This is a microbe that has solved the problem of how to live in a different way.”

This story is not about Mono Lake or arsenic, she said, but about “cracking open the door and finding that what we think are fixed constants of life are not.”

Dr. Wolfe-Simon and her colleagues publish their findings Friday in Science.

Gerald Joyce, a chemist and molecular biologist at the Scripps Research Institute in La Jolla, Calif., said the work “shows in principle that you could have a different form of life,” but noted that even these bacteria are affixed to the same tree of life as the rest of us, like the extremophiles that exist in ocean vents.

“It’s a really nice story about adaptability of our life form,” he said. “It gives food for thought about what might be possible in another world.

Phosphorus is one of six chemical elements that have long been thought to be essential for all Life As We Know It. The others are carbon, oxygen, nitrogen, hydrogen and sulfur.

While nature has been able to engineer substitutes for some of the other elements that exist in trace amounts for specialized purposes — like iron to carry oxygen — until now there has been no substitute for the basic six elements. Now, scientists say, these results will stimulate a lot of work on what other chemical replacements might be possible. The most fabled, much loved by science fiction authors but not ever established, is the substitution of silicon for carbon.

Phosphorus chains form the backbone of DNA and its chemical bonds, particularly in a molecule known as adenosine triphosphate, the principal means by which biological creatures store energy. “It’s like a little battery that carries chemical energy within cells,” said Dr. Scharf. So important are these “batteries,” Dr. Scharf said, that the temperature at which they dissolve, about 160 Celsius (320 Fahrenheit), is considered the high-temperature limit for life.

Arsenic sits right beneath phosphorus in the periodic table of the elements and shares many of its chemical properties. Indeed, that chemical closeness is what makes it toxic, Dr. Wolfe-Simon said, allowing it to slip easily into a cell’s machinery where it then gums things up, like bad oil in a car engine.

A bacterium known as strain GFAJ-1 of the Halomonadaceae family of Gammaproteobacteria, proved to grow the best of the microbes from the lake, although not without changes from their normal development. The cells grown in the arsenic came out about 60 percent larger than cells grown with phosphorus, but with large, empty internal spaces.

By labeling the arsenic with radioactivity, the researchers were able to conclude that arsenic atoms had taken up position in the microbe’s DNA as well as in other molecules within it. Dr. Joyce, however, said that the experimenters had yet to provide a “smoking gun” that there was arsenic in the backbone of working DNA.

Despite this taste for arsenic, the authors also reported, the GFAJ-1 strain grew considerably better when provided with phosphorus, so in some ways they still prefer a phosphorus diet.

http://www.nytimes.com/2010/12/03/science/03arsenic.html?pagewanted=1&_r=1&partner=rss&emc=rss