Archive for the ‘evolution’ category: Page 10

Mar 28, 2023

Associative learning in the cnidarian Nematostella vectensis

Posted by in category: evolution

The ability to learn and form memories allows animals to adapt their behavior based on previous experiences. Associative learning, the process through which organisms learn about the relationship between two distinct events, has been extensively studied in various animal taxa. However, the existence of associative learning, prior to the emergence of centralized nervous systems in bilaterian animals, remains unclear. Cnidarians such as sea anemones or jellyfish possess a nerve net, which lacks centralization. As the sister group to bilaterians, they are particularly well suited for studying the evolution of nervous system functions. Here, we probe the capacity of the starlet sea anemone Nematostella vectensis to form associative memories by using a classical conditioning approach. We developed a protocol combining light as the conditioned stimulus with an electric shock as the aversive unconditioned stimulus. After repetitive training, animals exhibited a conditioned response to light alone—indicating that they learned the association. In contrast, all control conditions did not form associative memories. Besides shedding light on an aspect of cnidarian behavior, these results root associative learning before the emergence of NS centralization in the metazoan lineage and raise fundamental questions about the origin and evolution of cognition in brainless animals.

Mar 27, 2023

Nonlinear evolution of the Weibel instability with relativistic laser pulses

Posted by in categories: evolution, particle physics

The Weibel instability is investigated using relativistic intense short laser pulses. A relativistic short laser pulse can generate a sub-relativistic high-density collisionless plasma. By irradiating double parallel planar targets with two relativistic laser pulses, sub-relativistic collisionless counterstreaming plasmas are created. Since the growth rate of the Weibel instability is proportional to the plasma density and velocity, the spatial and temporal scales of the Weibel instability can be much smaller than that from nanosecond large laser facilities. Recent theoretical and numerical studies have revealed that astrophysical collisionless shocks in sub-relativistic regimes in the absence and presence of an ambient magnetic field play essential roles in cosmic ray acceleration. With experimental verification in mind, we discuss the possible experimental models on the Weibel instability with intense short laser pulses. In order to show the experimental feasibility, we perform 2D particle-in-cell simulations in the absence of an external magnetic field as the first step and discuss the optimum conditions to realize the nonlinear evolutions of the Weibel instability in laboratories.

Mar 22, 2023

How runners stay upright on uneven terrain

Posted by in categories: evolution, mathematics

If you go running over a trail in the woods or a grassy field, there are countless bumps and dips in the terrain, each with the potential to trip you up. But typically, runners manage just fine. It’s a remarkable physical feat that we tend to take for granted. A team of researchers set out to better understand it.

With a specially made running track and mathematical modeling, the lab of Madhusudhan Venkadesan found that when running on uneven terrain, humans mostly rely on the body’s mechanical response for stability rather than consciously plot out their footsteps to find level ground. Further, they found that the were just as efficient in their movements and physical exertion as when running on flat ground. The results are published in eLife.

Even without occasional hazards like steep drops, runners must contend with gentler, but still uneven, ground that can be destabilizing. So why aren’t trails typically littered with toppled runners? One possibility is that allow runners to carefully observe the land to step on mostly level areas. On the other hand, running played a huge role in human evolution, particularly in how it benefited humans in hunting. That means sight cannot be devoted solely to find areas to step on; it’s also needed to watch out for the prey, trees or other obstacles to avoid, and decide which path to take.

Mar 21, 2023

Lab experiments suggest oxygen in early Earth’s atmosphere may have come from rocks

Posted by in categories: biotech/medical, evolution

A team of geochemists from the Chinese Academy of Sciences, working with colleagues from the University of Hong Kong, Tianjin University and the University of California, has found evidence that suggests much of the oxygen in early Earth’s early atmosphere may have come from rocks. In their study, reported in Proceedings of the National Academy of Sciences, the group conducted lab experiments involving crushing rocks, exposing the results to water and measuring reactive oxygen species that were emitted.

Prior research has shown that Earth experienced what has been called the Great Oxidation Event approximately 2.3 to 2.4 billion years ago. During this time, microbe numbers increased dramatically, as they released during photosynthesis. But prior research has also suggested that a common life ancestor existed before the Great Oxidation Event, which further suggests that there was some amount of oxygen exposure. In this new effort, the researchers suggest that such oxygen could have come from rocks interacting with water.

The work involved crushing samples of quartz and then exposing them to water, which replicates some of the conditions that existed on early Earth prior to the rise of high levels of oxygen in the atmosphere. Adding water to freshly crushed quartz, the researchers found, led to reactions between the water and newly broken crystals. This resulted it the formation of molecular oxygen along with other like hydrogen peroxide. Such species are also known as free radicals and they would have played an important role in the evolution of . This is because by damaging DNA and other cell components, the would have pressured early life to adapt.

Mar 18, 2023

Solving the paradox of how animals managed to evolve with bright colors without being eaten

Posted by in categories: evolution, food

A trio of evolutionary biologists, two with Carleton University, the other with Seoul National University, has apparently solved the paradox of aposematism—how animals managed to evolve with bright colors to warn predators of their toxic nature. In their paper study, published in the journal Science, Karl Loeffler-Henry, Changku Kang and Thomas Sherratt, conducted an analysis of the family tree of over 1,000 frog, salamander and newt species.

For many years, have puzzled over the seeming paradox of aposematism, in which such as frogs develop to warn potential predators that eating them will make them sick or even kill them. How could such colors have evolved? Animals that stand out tend to be the first caught and eaten, preventing the evolution of even brighter colors from occurring. In this new effort, the research team set out to solve this riddle.

The work involved analyzing the of 1,100 species of frogs, salamanders and newts, looking for evidence of evolution of aposematism in a new way—by breaking them down into more categories than previous efforts—five instead of two: conspicuous, cryptic, partially conspicuous, fully conspicuous and polymorphic.

Mar 15, 2023

Fundamental constants: Is the universe fine-tuned for life?

Posted by in categories: alien life, evolution, information science, particle physics

Imagine a universe with extremely strong gravity. Stars would be able to form from very little material. They would be smaller than in our universe and live for a much shorter amount of time. But could life evolve there? It took human life billions of years to evolve on Earth under the pleasantly warm rays from the Sun after all.

Now imagine a with extremely weak gravity. Its matter would struggle to clump together to form stars, planets and—ultimately—living beings. It seems we are pretty lucky to have gravity that is just right for life in our universe.

This isn’t just the case for gravity. The values of many forces and in the universe, represented by some 30 so-called fundamental constants, all seem to line up perfectly to enable the evolution of intelligent life. But there’s no theory explaining what values the constants should have—we just have to measure them and plug their numbers into our equations to accurately describe the cosmos.

Mar 15, 2023

Imagination makes us human—this unique ability to envision what doesn’t exist has a long evolutionary history

Posted by in categories: evolution, neuroscience

You can easily picture yourself riding a bicycle across the sky even though that’s not something that can actually happen. You can envision yourself doing something you’ve never done before—like water skiing—and maybe even imagine a better way to do it than anyone else.

Imagination involves creating a mental image of something that is not present for your senses to detect, or even something that isn’t out there in reality somewhere. Imagination is one of the key abilities that make us human. But where did it come from?

I’m a neuroscientist who studies how children acquire . I’m especially interested in the neurological mechanisms of imagination. Once we identify what brain structures and connections are necessary to mentally construct new objects and scenes, scientists like me can look back over the course of evolution to see when these emerged—and potentially gave birth to the first kinds of imagination.

Mar 15, 2023

Sniper2L is a high-fidelity Cas9 variant with high activity Chemical Biology

Posted by in categories: biological, chemistry, evolution

Kim et al. used directed evolution methods to identify a high-fidelity SpCas9 variant, Sniper2L, which exhibits high general activity but maintains high specificity at a large number of target sites.

Mar 11, 2023

Scientists May Have Found Evidence of Earth’s “Inner Inner” Core

Posted by in category: evolution

The inner workings of our planet are getting weirder.

For generations, scientists have probed the structure and composition of the planet using seismic wave studies. This consists of measuring shock waves caused by earthquakes as they penetrate and pass through the Earth’s core region. By noting differences in speed (a process known as anisotropy), scientists can determine which regions are denser than others. These studies have led to the predominant geological model that incorporates four distinct layers: a crust and a mantle (composed largely of silicate minerals) and an outer core and inner core composed of nickel-iron.

According to seismologists from The Australian National University (ANU), data obtained in a recent study has shed new light on the deepest parts of Earth’s inner core. In a paper that appeared in Nature Communications, the team reports finding evidence for another distinct layer (a solid metal ball) in the center of Earth’s inner core — an “innermost inner core.” These findings could shed new light on the evolution of our planet and lead to revised geological models of Earth that include five distinct layers instead of the traditional four.

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Mar 9, 2023

How Do Supermassive Black Holes Form? Study Reveals Huge Galaxy Mergers During Cosmic Noon Play an Important Role in This Celestial Formation

Posted by in categories: cosmology, evolution

The cosmos is full of mysteries, one of which is the existence of supermassive black holes. Though much effort has been granted to these celestial mysteries, the evolution and formation of such supermassive black holes are quite hard to explain.

Supermassive Black Holes

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