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Scientists also reconstructed what they believe that first flower looked like: Somewhat similar to a water lily, with circles of broad petals around a center of protruding pollen spikes.

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I posted this work earlier, but am sharing again because I think it is an important way of viewing life on this planet.

Plus, I want to call out +Eli Fennell's introductory remarks in his share, and this line in particular:

It was not idyllic conditions that gave rise to life on this planet, in effect, but rather life that made our world idyllic...

Excellent way to describe it. Sort of reminds me of the notion of the "adjacent possible" that Stuart Kauffman talks about.
The 'Energy Revolutions' That Powered Evolution

Understanding how life evolved as it did on Earth is a fundamental quest of the evolutionary sciences, with applications both for the life history of our world as well as the quest to find life elsewhere in the cosmos.

It has long been considered helpful to describe life history on this planet as a series of unfolding stages. Not only does such an approach make it easier to understand, but also fits with the fossil evidence showing life occurring in a series of 'explosions' of new categories and forms of life (i.e. evolution is an ongoing process, but speciation and the emergence of new categories of lifeforms occurred far more rapidly during certain periods).

A new article published in Nature Ecology and Evolution suggests a new and foundational way to categorize the stages of life on Earth as a series of energy epochs, as living things accessed new and better forms of energy.

Broadly, the suggested schema identifies five overlapping epochs: geochemical energy, sunlight, oxygen, flesh, and fire. Each of these was, at one time, not yet exploited or not exploited at all by living things, but as each became more and more available to life, new categories of living things exploded in response to these 'energy revolutions', expanding to fill every new niche made available, and increasing in complexity with the increasing richness and efficiency of the energy sources available.

While it may not yet be possible to predict the next epoch in the energy sources of life, or even if there will be one, knowing the role energy availability played in the evolution of life over our planetary history may be useful for identifying cosmic 'candidate habits' which might host life. The search for 'Earth-like' planets, in fact, may be overly narrow, and the important question may not be whether a planet looks like Earth, but whether it possesses the energetic 'ingredients' first for simple lifeforms, and then the more complex life made possible in part by the existence of those earlier forms.

After all, when life first evolved on Earth, the planet was utterly inhospitable for any of the complex forms inhabiting our modern world, and it was those earlier and simpler lifeforms themselves that helped 'terraform' us, for example by releasing large amounts of oxygen into the atmosphere, or simply by existing to function as food sources for each other (whether consumed, as a predator eats its prey, decomposed as by microbes, or broken down into soil and absorbed as by plant roots).

It was not idyllic conditions that gave rise to life on this planet, in effect, but rather life that made our world idyllic, its biochemical machinery powered at each stage by more and more complex and efficient energy forms, each 'setting the stage' for the next categories of life to follow.

#BlindMeWithScience #Evolution

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Energy and Life

I've heard much of this before, but it is the frame of thinking of Earth's stages of Life in terms of different types of energy consumption that is so interesting here.

The history of the life–Earth system can be divided into five ‘energetic’ epochs, each featuring the evolution of life forms that can exploit a new source of energy. These sources are: geochemical energy, sunlight, oxygen, flesh and fire. The first two were present at the start, but oxygen, flesh and fire are all consequences of evolutionary events.

A few interesting excerpts:
For the purposes of this Perspective, however, one feature of eukaryotes is particularly important. This is the ability to engage in phagocytosis—the engulfment of particles and, sometimes, other life forms. The wholesale engulfment of other beings appears to be a eukaryotic invention, and it whets the appetite for...Energy epoch four: flesh

...
Today, animals influence diversity at all levels of an ecosystem, with grazers such as slugs96 or zooplankton97 maintaining the diversity of plants or phytoplankton, and carnivores such as wolves98 maintaining the diversity of plants through their predation on herbivores. This kind of ecology—complex food webs with many types of eaters—was absent from Earth until around 550 Ma, when the first animals that eat animals evolved. Their appearance seems to have triggered the rapid diversification of animal life sometimes referred to as the Cambrian Explosion.

...
Of all the planets and moons in the Solar System, Earth is the only one to have fire. This is because, to have fire, all of three conditions must be met. (1) Fire needs a source of ignition—such as lightning strikes...Fire needs oxygen...Fire needs fuel. So it is not until the evolution of vascular plants on land, around 420 Ma, that all three conditions were met.

In addition to fire being used for cooking, it has other far-reaching, and more recent, applications:

The second phase of fire as an energy source is even more recent—but the onset is nonetheless difficult to pinpoint. Does it start with the use of fire to manufacture labour-saving tools? With the smelting of iron, something otherwise energetically impossible? With the burning of fossil fuels such as coal to generate heat and light? With the invention of the internal combustion engine? Or with the discovery of the Haber–Bosch process for fixing nitrogen—which, in 1925, Alfred Lotka described as the start of “a new cosmic epoch”? Perhaps these last three are the most important contenders, as together, they have transformed the planet. In particular, the human input of energy to manufacture and deliver an otherwise limiting nutrient has produced far higher crop yields, enormously larger human populations, and gigantic populations of human-associated animals such as pigs, cows, horses and chickens. Erisman and colleagues estimate that between 1908 and 2008, industrially produced nitrogen fertilizer supported an additional four billion people and that by 2008, nitrogen fertilizers were responsible for feeding 48% of the human population. Meanwhile, Pimm and colleagues judge that extinction rates are now 1,000 times greater than the typical background rate. In sum, in this epoch of fire, total biomass has remained high, but biodiversity has begun to fall.

...
From this point of view, the familiar observation that Earthly life is powered by the sun takes on a more nuanced aspect: the modern biosphere is powered not merely by sunshine but by the oxygen that results from using sunshine in a particular way.

This Perspective further suggests that, through the harnessing of fire as a source of energy, Earth has now arrived at a new inflection point. Considering life–Earth history through the lens of energy expansions supports the view that the Anthropocene is a genuinely novel phase of the planet's geological and biological development—a conclusion independently reached by Lenton and colleagues. The technology of fire may also, perhaps, mark an inflection point for the Solar System and beyond. Spacecraft from Earth may, intentionally or not, take Earthly life to other celestial objects (though whether any Earthly life forms can thrive elsewhere remains unknown).

Thanks to +Vladimir Pecha for this one. Also, +Edward Morbius, this sounds like something you'd like (and something you've said yourself).



The energy expansions of evolution

The history of the life–Earth system can be divided into five ‘energetic’ epochs, each featuring the evolution of life forms that can exploit a new source of energy. These sources are: geochemical energy, sunlight, oxygen, flesh and fire. The first two were present at the start, but oxygen, flesh and fire are all consequences of evolutionary events. Since no category of energy source has disappeared, this has, over time, resulted in an expanding realm of the sources of energy available to living organisms and a concomitant increase in the diversity and complexity of ecosystems. These energy expansions have also mediated the transformation of key aspects of the planetary environment, which have in turn mediated the future course of evolutionary change. Using energy as a lens thus illuminates patterns in the entwined histories of life and Earth, and may also provide a framework for considering the potential trajectories of life–planet systems elsewhere.

https://www.nature.com/articles/s41559-017-0138

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This deep dive into chemistry is not complete without following the links, which as usual with +David Amerland's Sunday Read.

David is an excellent guide in these weekly tours of one topic after another.
Affinity

Chemistry, for me, has always been a doorway into a magical world. Particularly given the fact that organic and applied chemistry (the domains that drew me into the most during my Chemical Engineering days) were given birth in the idle dream of one man while, if his account is truly to be believed, dozing on the upper decks of a horse-drawn, London omnibus.

August Kekulé (https://goo.gl/e2f4Ut), single-handedly, opened the doorway into understanding some of nature’s innermost secrets, giving us insights in what everything is made up of: https://goo.gl/cjCL58.

The importance of Chemistry is not to be underestimated, particularly when even events as seemingly cut-and-dry as the Hinderberg disaster are still open to re-interpretation the moment a better understanding of chemistry (and a single element) enters the picture: https://goo.gl/l2aZsw.

Because everything is made up of chemicals of one type or another, chemistry allows the easy transfer of knowledge from one situation to another where the specific chemical structures studied are present such as a one hundred and fifty years old photograph and a modern oil pipeline: https://goo.gl/YOriV6.

What is even more fascinating is that chemistry existed, as a discipline, long before it existed as a science. Its ancestor, Alchemy (https://goo.gl/DuLcrW) blended a unique mix of experiment and philosophy, belief and faith into a potent whole that for a while promised to solve almost every ill mankind faced: https://goo.gl/zpAoOo.

The search for the Philosopher’s Stone (https://goo.gl/mZscY0) powered a generation of pioneers who delved into the chemical world that surround us in search of secrets that would change everything. Amongst the names of those who joined the hunt were luminaries such as physicist Isaac Newton (https://goo.gl/OhD8Yx) whose own approach to science included a liberal dose of alchemy.

When studying I was absorbed, at one stage, by a course labelled “the philosophy of chemistry” (https://goo.gl/z8fgUs). It drove home to me back then, that we cannot do anything without basing it on some fundamental assumptions that reveal some of our innermost beliefs and what we believe always plays a role in the actions we take and the assumptions we make, regardless of how logical or unbiased we claim to be.

For some of the practical applications of Chemistry this brief TED-style introduction to the subject is quite revealing (https://goo.gl/QYlJ07).

In true alchemical style, chemistry affects so much of our lives that something as seemingly innocuous as oil has the ability to change the political landscape, shape countries and define systems of governance: https://goo.gl/kqLQtU.

Because life itself sprung from a chemical mix (the so-called primordial soup - https://goo.gl/5a6qFI) we cannot ever escape our chemistry. We are a complex composition of seemingly simple compounds (https://goo.gl/8RWvBI), held together by the affinity (https://goo.gl/IwNxfO) they display for each other.

What few of us realize is that we are all chemists whether we know it or not. Cooking (https://goo.gl/igA0hv) is all about chemistry and it can easily be viewed as alchemy: https://goo.gl/CKvjdF. That’s an approach that some people take very seriously as they search for the perfect French fry or the best way to brown meat: https://goo.gl/FCuYvJ.

There is a secret at the heart of chemistry and it is this: Chemistry is all about the transfer of heat (https://goo.gl/FCuYvJ). There is no chemical process that can take place at absolute zero (https://goo.gl/rgt7be). This then makes chemistry part of physics and biology. Part of neuroscience (https://goo.gl/ZDm9y) and mathematics: https://goo.gl/tp8GOA.

When something is as vital and fundamental as that that it is woven into practically everything, including Quantum Mechanics (https://goo.gl/1JKOvC) we then understand that what we know about it and what we think has the ability to change how we view the world and ourselves.

To make the point consider that chemistry plays a role in the cookies (https://goo.gl/ghq7oF) you should have with you today. It affects the rivers of coffee (https://goo.gl/XySRoR) that power your deeper thinking. It powers the cake (https://goo.gl/JFZbNx) that should be at hand. And it transforms coffee and donuts into the breakfast of champions (https://goo.gl/wH6yF9). Secretly, we’ve known all this forever, intuitively. Have an awesome Sunday, wherever you are.
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Figuring Out Cool Stuff

Scientists have determined that the way scale patterns form on lizards is a kind of cellular automaton:

Originally conceived in the 1940s, a cellular automaton3, 4 is a system of spatially discrete but interconnected units that switch between different states depending on their own state and the states of their neighbours. Cellular automata have been used to probe theoretical concepts in computer science (such as a universal Turing machine), study complex patterns in nature6, produce startling moving patterns based on simple rules (the 'Game of Life') and model biological systems and a panoply of discrete systems that are too numerous to list.

The experiment design used to uncover this aspect of natural design is almost as beautiful as the discoveries themselves. Almost. I love seeing super creative experiment design aimed at solving interesting problems like this.

Yay science. I feel like I should March for you. At least I'm glad others are:
https://www.marchforscience.com/

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Understanding the Deep, Dark Ocean Waters of the Mesopelagic

Scientists are now working to better understand that portion of the ocean, hundreds of meters deep, where little light penetrates. One of the key things that popped from this article was this part about the mesopelagic's critical role in the carbon cycle:

As ecosystems go, it is an odd one. Its inhabitants are in a state of perpetual migration, rising to the surface at night to feed, then returning to depths of between 200 metres and 1km at dawn, to escape predation. It is this migration, the biggest in the world, that drives the carbon pump. The nocturnal feasting consumes prodigious amounts of that climate-changing element in the form of small, planktonic creatures. Then, during the day, the feasters release part of what they have consumed as faeces. Some of them also die. These faeces and bodies fall through the water column as what is known as marine snow, and accumulate at the bottom. Without mesopelagic predators, far more plankton would die in the surface waters, their bodily carbon returned rapidly to the atmosphere. The vast harmless reservoir of carbon in the depths would thus be a little smaller; the damaging burden of atmospheric carbon a good bit greater.

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The measurements confirmed that a mosquito's wings beat at a frequency of over 700Hz. This is much faster than most other insects and explains the mosquito's distinctive whine. The other distinctive feature is that the sweep of the wing (the total angle it travels) during the wing beat is less than 40 degrees—"less than half the smallest amplitude yet measured for any hovering animal."

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Older, Northern, Re-Org'ed Dinos

Baron’s tree rewrites the first chapters of the dinosaur story in several ways. It suggests that they first arose around 247 million years ago, slightly earlier than the 231 to 243 million year range that’s typically cited. It hints that they might have originated in the northern half of the world rather than the southern half. And most importantly, it says that the ancestral dinosaurs split into two major groups—just not the ones we traditionally recognize.

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Amazing voyage through the human body.

HT +Andreas Englund.

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Bacteria use electrical pulses to organize their communities and to coordinate with neighbors

Think about it this way. When bacteria communicate chemically, it’s like each family is speaking with its own language, relying on its own particular assortment of chemicals and receptors. By contrast, the electrical signals that Süel’s team discovered are more like mathematics—something universal. “It allows species to communicate across evolutionary divides and create mixed communities,” says Humphries. “It’s changed my perspective on biofilms.”
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