At the viral chatter stage of an outbreak, pathogens are just starting to infect people in sporadic bursts. It’s a sign that a pandemic may be on the horizon.
Category: evolution – Page 3
Millions of years before the asteroid impact that ended the reign of the dinosaurs, mammals were already beginning to shift from tree-dwelling to ground-based lifestyles.
A groundbreaking study uncovered this evolutionary trend by analyzing tiny limb bone fragments from marsupials and placental mammals in Western North America. These subtle fossil clues reveal that mammals may have been responding to a changing world, especially the spread of flowering plants that transformed habitats on the ground. Surprisingly, this terrestrial transition appears to have played a bigger role in mammalian evolution than direct interactions with dinosaurs.
Early Ground-Dwellers Before Dinosaurs’ Demise.
1999/ 2000 documentary 56 minutes. Primal Eye/ Median Vision Theory of the early evolution of self referential consciousness and dreaming. Dir…
Humans like to think that being multicellular (and bigger) is a definite advantage, even though 80% of life on Earth consists of single-celled organisms—some thriving in conditions lethal to any beast.
In fact, why and how multicellular life evolved has long puzzled biologists. The first known instance of multicellularity was about 2.5 billion years ago, when marine cells (cyanobacteria) hooked up to form filamentous colonies. How this transition occurred and the benefits it accrued to the cells, though, is less than clear.
A study originating from the Marine Biological Laboratory (MBL) presents a striking example of cooperative organization among cells as a potential force in the evolution of multicellular life. Based on the fluid dynamics of cooperative feeding by Stentor, a relatively giant unicellular organism, the report is published in Nature Physics.
Researchers from the Institute of Solid State Physics, the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, in collaboration with Southwest Jiaotong University, have combined high-pressure electrical transport experiments, high-pressure Raman spectroscopy, and first-principles calculations to reveal the structural phase transition behavior of hafnium oxide (HfO2) under high pressure and its evolution mechanism in electrical properties.
The paper is published in the journal Physical Review B.
“This study resolves the previous controversies regarding the phase transitions of HfO2 in the low-pressure region,” said Pan Xiaomei, a member of the team.
Every time the temperature drops, a cloud passes overhead, or the sun sets, a plant makes a choice: Keep its microscopic pores, called stomata, open to absorb carbon dioxide and continue photosynthesizing or close them to protect its precious stores of water. That capacity to open and close pores requires the plant to respond to subtle environmental changes by adjusting the pressure within the cells of the stomata—a complex ability that plants evolved over hundreds of millions of years.
An interdisciplinary team of biologists, physicists, and engineers, led by researchers at the Yale School of the Environment, has developed a method to observe those pressure changes. The new approach, detailed in a study published in PNAS, vastly expands the rate at which—and the number of species from which—scientists can take measurements, opening up new possibilities for research on plant evolution and physiology with valuable applications for improving water efficiency, the researchers said.
“Almost every single land plant is using this principle of internal pressure in order to grow, reproduce, and do everything a plant does, but we previously had basically no access to this measurement,” said Craig Brodersen, the Howard and Maryam Newman Professor of Plant Physiological Ecology and the lead author of the study.
You may have heard of the fantastic-sounding “dark side of the genome.” This poorly studied fraction of DNA, known as heterochromatin, makes up around half of your genetic material, and scientists are now starting to unravel its role in your cells.
For more than 50 years, scientists have puzzled over the genetic material contained in this “dark DNA.” But there’s a growing body of evidence showing that its proper functioning is critical for maintaining cells in a healthy state. Heterochromatin contains tens of thousands of units of dangerous DNA, known as “transposable elements” (or TEs). TEs remain silently “buried” in heterochromatin in normal cells—but under many pathological conditions they can “wake up” and occasionally even “jump” into our regular genetic code.
And if that change benefits a cell? How wonderful! Transposable elements have been co-opted for new purposes through evolutionary history—for instance the RAG genes in immune cells and the genes required for driving the development of the placenta and mammalian evolution have been derived from TEs.
New in JNeurosci: In a study comparing human brains to macaque and chimpanzee brains, Bryant et al. discovered neuroanatomical features that are unique to humans.
Learn more. ▶️
Determining the brain specializations unique to humans requires directly comparative anatomical information from other primates, especially our closest relatives. Human (Homo sapiens) (m/f), chimpanzee (Pan troglodytes) (f), and rhesus macaque (Macaca mulatta) (m/f) white matter atlases were used to create connectivity blueprints, i.e., descriptions of the cortical grey matter in terms of the connectivity with homologous white matter tracts. This allowed a quantitative comparative of cortical organization across the species. We identified human-unique connectivity profiles concentrated in temporal and parietal cortices, and hominid-unique organization in prefrontal cortex. Functional decoding revealed human-unique hotspots correlated with language processing and social cognition. Overall, our results counter models that assign primacy to prefrontal cortex for human uniqueness.
Significance statement Understanding what makes the human brain unique requires direct comparisons with other primates, particularly our closest relatives. Using connectivity blueprints, we compared to cortical organization of the human to that of the macaque and, for the first time, the chimpanzee. This approach revealed human-specific connectivity patterns in the temporal and parietal lobes, regions linked to language and social cognition. These findings challenge traditional views that prioritize the prefrontal cortex in defining human cognitive uniqueness, emphasizing instead the importance of temporal and parietal cortical evolution in shaping our species’ abilities.
Klein bottle
Posted in evolution, space | Leave a Comment on Klein bottle
Suppose for clarification that we adopt time as that fourth dimension. Consider how the figure could be constructed in xyzt-space. The accompanying illustration (“Time evolution…”) shows one useful evolution of the figure. At t = 0 the wall sprouts from a bud somewhere near the “intersection” point. After the figure has grown for a while, the earliest section of the wall begins to recede, disappearing like the Cheshire Cat but leaving its ever-expanding smile behind. By the time the growth front gets to where the bud had been, there is nothing there to intersect and the growth completes without piercing existing structure. The 4-figure as defined cannot exist in 3-space but is easily understood in 4-space. [ 4 ]
More formally, the Klein bottle is the quotient space described as the square [0,1] × [0,1] with sides identified by the relations (0, y) ~ (1, y) for 0 ≤ y ≤ 1 and (x, 0) ~ (1 − x, 1) for 0 ≤ x ≤ 1.
New research led by a York University professor sheds light on the earliest days of Earth’s formation and potentially calls into question some earlier assumptions in planetary science about the early years of rocky planets. Establishing a direct link between Earth’s interior dynamics occurring within the first 100 million years of its history and its present-day structure, the work is one of the first in the field to combine fluid mechanics with chemistry to better understand Earth’s early evolution.
The study is published in the journal Nature.
“This study is the first to demonstrate, using a physical model, that the first-order features of Earth’s lower mantle structure were established four billion years ago, very soon after the planet came into existence,” says lead author Faculty of Science Assistant Professor Charles-Édouard Boukaré in the Department of Physics and Astronomy at York.