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Forces that work life's shapes + Organisms do not evolve blind + 1st life on islands?

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The secret forces that squeeze and pull life into shape
https://www.nature.com/articles/d41586-021-00018-x

EXCERPTS: . . . Over the past 20 years, more scientists have started paying attention to the importance of mechanics across a variety of developmental stages, organs and organisms. Researchers have begun to define the mechanisms by which cells sense, respond to and generate forces. They have done so by inventing bespoke tools and tricks, incorporating lasers and micropipettes, magnetic particles and custom-built microscopes. Most researchers are probing mechanical signals using cells or tissues cultured in a dish. But a few groups are studying whole animals, and sometimes they find different principles at work from those apparent in isolated tissues. These in vivo studies come with many challenges — such as measuring tiny amounts of force in complex tissues — but they are key to understanding the role of force in sculpting life, says Roberto Mayor, a developmental biologist at University College London.

As a handful of determined scientists begin to surmount those challenges, they’ve observed crucial forces shaping biology — from the earliest stages of an embryo’s existence to diseases that strike later in life. Down the line, this information might help scientists to design better interventions for problems such as infertility or cancer. “Forces will operate in every single instance where shape is at play,” says Thomas Lecuit, a developmental biologist at the Developmental Biology Institute of Marseille in France.

[...] Next, Fuchs and Fiore plan to investigate how the cells perceive these mechanical forces, and how they convert the force into a program of gene expression that might produce more basement membrane or promote differentiation.

That question — how forces and genes are linked — is key, says Alan Rodrigues, a developmental biologist at the Rockefeller University. And it’s not just an issue for skin cancer. “The deep question in mechanics is actually thinking about how it relates to molecules,” he says.

Others, too, are investigating this link. “It’s not just, you know, ‘genes do everything’ or ‘mechanics does everything’,” says Lecuit. “It’s going to be an interesting dialogue between the two.” (MORE - details)


First life could have evolved on ancient islands
https://www.livescience.com/ancient-island-life.html

EXCERPTS: . . . Some scientists believe that the first microbial life emerged at undersea hydrothermal vents [...] Other scientists argue that vents put off too much heat for effective polymerization ... In this camp, researchers argue that life, instead, emerged at the edges of shallow ponds, heated by geothermal energy.

For the warm-water pool hypothesis to work, though, early Earth needs to have hosted solid ground ... That's where the new study, published Jan. 4 in the journal Nature Geoscience, comes in. Geoscientists Jun Korenaga and Juan Carlos Rosas [...] are interested in understanding the topography of the Earth during the Archean era, 4 billion to 2.5 billion years ago. Chemist Jeffrey Bada, a proponent of the warm-pond hypothesis ... approached Korenaga and asked if there was any possibility of dry land during the Archaean.

Korenaga and Rosas used a computer model to recreate the conditions of the Archaean Earth. Today [...] new ocean floor forms at mid-ocean ridges, where rocks from deep within Earth’s middle layer, the mantle, rise up and melt, creating new oceanic crust. As this crust slides away from its origin at the mid-ocean ridge (which looks like an underwater mountain range), it cools and contracts, becoming denser and dropping in elevation.

Meanwhile, though, Earth has its own source of internal heat: radiogenic heating, put off by the decay of radioactive elements in the deep mantle. This heat tends to push upward, ultimately raising the elevation at the surface. During the Archaean, this radiogenic heating was stronger. This means that even as the new oceanic crust cooled and contracted, it was pushed upward. This could have led to underwater seamounts [...] being pushed up above sea level, forming islands.

The findings suggest that there could have been dry land on Earth well before the formation of large continents. "This warm-water ponds hypothesis has a very solid geological foundation," Korenaga said.

That doesn't mean that the hypothesis is correct, of course; but the new study reveals that warm-water ponds can't be ruled out based on geology alone. Geochemists are working to figure out the constraints of life-friendly chemistry on land, Korenaga said. "It's a very rich subject..." (MORE - details)


Organisms do not evolve blindly under forces beyond their control, but shape and influence the evolutionary environment itself
https://aeon.co/essays/organisms-are-not...ary-forces

INTRO: Humans are shaping the evolutionary future of life on Earth. We’re not only causing mass extinctions, we’re also forcing animals, plants and fungi to adapt to our manufactured world: city birds, for instance, are now singing higher notes, since the pitch seems to help their song carry over the sound of traffic. But while cultural knowledge and engineering have upgraded the human capacity to catalyse environmental change, the proclivity is common to all species.

Scatter a few bacteria in a Petri dish and they will produce nutrient-rich byproducts that new bacteria strains can exploit, rapidly causing a multitude of diverse microbial populations to evolve. Beavers create ponds that are used as breeding grounds for ducks; web spiders make retreats that are exploited as hibernation sites by earthbound insects; plants modify soils through substances secreted from their roots. The way these organisms change their environment in turn changes the evolutionary pressures that they and others face as they struggle to survive and reproduce. Their actions, in other words, bias what is selected for.

This process is known as ‘niche construction’ and all species do it, even if their effects are sometimes more modest and localised than ours. Yet the theory of niche construction is controversial among evolutionary biologists, partly because natural selection is traditionally believed to work ‘blindly’: it is thought to sculpt organisms over millennia to become adapted to their ecological niches, with no steer from the goals or purposes of organisms.

Humans undergo the same sculpting, but rather than evolving to fit a pre-existing niche, it’s widely accepted that we’re active agents who shape the environments to which we adapt. Our brains have evolved to process linguistically encoded information and learned knowledge because we built a rich cultural realm and then adapted to it. We domesticated plants and animals and, by incorporating them into our diets, triggered selection for genes that metabolise these foods. We invented agriculture, which fuelled population growth, inadvertently selecting for genetic resistance to diseases of the crowd such as typhoid or cholera. Our parents don’t just transmit their genes to us; we also inherit the changed world they leave in their wake.

This ecological inheritance means that humans don’t evolve in response to a static adaptive landscape, but instead mould that landscape to alleviate or intensify the particular selective pressures it places upon us. ‘[T]he organism influences its own evolution, by being both the object of natural selection and the creator of the conditions of that selection,’ as the evolutionary biologists Richard Levins and Richard Lewontin put it. Controversy comes from the fact that experts disagree about the extent to which other creatures can also direct evolution by terraforming their adaptive landscapes. The landscape metaphor can be a helpful one for understanding evolutionary processes.. (MORE)
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