Comment

Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 10:41am

Study Finds Life on Earth Emerged 4.2 Billion Years Ago

Once upon a time, Earth was barren. Everything changed when, somehow, out of the chemistry available early in our planet's history, something started squirming – processing available matter to survive, to breed, to thrive.

What that something was, and when it first squirmed, have been burning questions that have puzzled humanity probably for as long as we've been able to ask "what am I?"

Now, a new study has found some answers – and life emerged surprisingly early.

By studying the genomes of organisms that are alive today, scientists have determined that the last universal common ancestor (LUCA), the first organism that spawned all the life that exists today on Earth, emerged as early as 4.2 billion years ago.

Earth, for context, is around 4.5 billion years old. That means life first emerged when the planet was still practically a newborn.

Back when it was new, Earth was a very different place, with an atmosphere that we would find extremely toxic today. Oxygen, in the amount current life seems to need, didn't emerge until relatively late in the planet's evolutionary history, only as early as around 3 billion years ago.

But life emerged prior to that; we have fossils of microbes from 3.48 billion years ago. And scientists think that conditions on Earth may have been stable enough to support life from around 4.3 billion years ago.

But our planet is subject to erosional, geological, and organic processes that make evidence of that life, from that time, almost impossible to find.

a team of scientists went looking somewhere else: in genomes from living organisms, and the fossil record.

Their study is based on something called a molecular clock. Basically, we can estimate the rate at which mutations occur, and count the number to determine how much time has passed since the organisms in question diverged from common ancestors.

All organisms, from the humblest microbe to the mightiest fungus, have some things in common. There's a universal genetic code. The way we make proteins is the same. There's an almost universal set of 20 amino acids that are all oriented the same way. And all living organisms use adenosine triphosphate (ATP) as a source of energy in their cells.

Researchers  worked out, based on these similarities and differences, how long it has been since LUCA's successors started to diverge. And, using complex evolutionary modeling, they were able to learn more about LUCA itself – what it was, and how it survived on an Earth so very inhospitable to its descendants.

Part1

Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 9:17am

Urban animals modify their behaviors, learning, and problem-solving skills to cope with urban challenges, reflecting a dynamic response to urban landscapes," they write. "Similarly, humans alter their urban spaces, influencing wildlife behavior and evolution. This reciprocal adaptation between humans and wildlife is fundamental to understanding co-culture."
----
Future research is also needed to examine the possibility of cultural and genetic co-evolution—the idea that species' cultures and genomes are evolving in concert. A key question, the researchers say, is "In the context of co-culture, how do cultural adaptations influence genetic evolution, and vice versa, across different species and environments?"
----

Cédric Sueur et al, Co-cultures: exploring interspecies culture among humans and other animals, Trends in Ecology & Evolution (2024). DOI: 10.1016/j.tree.2024.05.011

Part 2

• Animals interact both within and between species, sharing common spaces.
• Animals exhibit cultural behaviours.
• Animals can influence and learn from each other, including interactions with other species.
• The co-culture concept suggests that two populations of different species can influence each other's cultures through synchronised activities.
• Co-culture emphasises cultural adaptations within ecological niches.

Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 9:16am

Introducing co-cultures: When co-habiting animal species share culture

Cooperative hunting, resource sharing, and using the same signals to communicate the same information—these are all examples of cultural sharing that have been observed between distinct animal species. In an opinion piece published June 19 in the journal Trends in Ecology & Evolution, researchers introduce the term "co-culture" to describe cultural sharing between animal species. These relationships are mutual and go beyond one species watching and mimicking another species' behavior—in co-cultures, both species influence each other in substantial ways.

Co-culture challenges the notion of species-specific culture, underscoring the complexity and interconnectedness of human and animal societies, and between animal societies," write the authors.

These cross-species interactions result in behavioral adaptations and preferences that are not just incidental but represent a form of convergent evolution.

Co-cultures have been observed between humans and nonhuman animals—for example, between humans and honeyguides in Tanzania and Mozambique, where the birds lead humans to honeybee nests. They are also evident between different species of nonhuman animals—for example, cooperative scavenging between ravens and wolves, cooperative hunting between false killer whales and bottlenose dolphins, and signal sharing between distinct species of tamarin. Ultimately, this inter-species sharing of culture could drive evolution, the researchers say.

"Cultural behaviors that enhance survival or reproductive success in a particular setting can lead to changes in population habits that, over time, could drive genetic selection," they write.

To extend our understanding of co-cultures, the researchers say that future studies could start by investigating wild animals in urban environments.

Part 1

Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 9:12am

New study finds 40% of cancer cases and almost half of all deaths  linked to modifiable risk factors

A study led by researchers at the American Cancer Society (ACS) finds four in 10 cancer cases and about one-half of all cancer deaths in adults 30 years old and older could be attributed to modifiable risk factors, including cigarette smoking, excess body weight, alcohol consumption, physical inactivity, diet, and infections.

Cigarette smoking was by far the leading risk factor, contributing to nearly 20% of all cancer cases and 30% of all cancer deaths. The findings are published in the journal CA: A Cancer Journal for Clinicians.

The risk factors included cigarette smoking (current and former smoking); secondhand smoke; excess body weight; alcohol consumption; consumption of red and processed meat; low consumption of fruits and vegetables, dietary fiber, and dietary calcium; physical inactivity; ultraviolet (UV) radiation; and infection with Epstein-Barr virus (EBV), Helicobacter pylori, hepatitis B virus (HBV), hepatitis C virus (HCV), human herpes virus-8 (HHV-8; also called Kaposi sarcoma herpesvirus), human immunodeficiency virus (HIV), and human papillomavirus (HPV). 

CA: A Cancer Journal for Clinicians (2024)

Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 9:01am

These new results reveal a mystery. In the largest animals, there is something preventing brains from getting too big. Whether this is because big brains beyond a certain size are simply too costly to maintain remains to be seen. But as we also observe similar curvature in birds, the pattern seems to be a general phenomenon—what causes this 'curious ceiling' applies to animals with very different biology.

Chris Venditti et al, Co-evolutionary dynamics of mammalian brain and body size, Nature Ecology & Evolution (2024). DOI: 10.1038/s41559-024-02451-3

Part 2

Comment by Dr. Krishna Kumari Challa on July 15, 2024 at 9:00am

Brain size riddle solved as humans exceed evolutionary trend

The largest animals do not have proportionally bigger brains—with humans bucking this trend—a study published in Nature Ecology & Evolution has revealed.

Researchers collected an enormous dataset of brain and body sizes from around 1,500 species to clarify centuries of controversy surrounding brain size evolution.

Bigger brains relative to body size are linked to intelligence, sociality, and behavioral complexity—with humans having evolved exceptionally large brains. The new research reveals the largest animals do not have proportionally bigger brains, challenging long-held beliefs about brain evolution.

For more than a century, scientists have assumed that this relationship was linear—meaning that brain size gets proportionally bigger, the larger an animal is. We now know this is not true. The relationship between brain and body size is a curve, essentially meaning very large animals have smaller brains than expected.

The research reveals a simple association between brain and body size across all mammals which allowed the researchers to identify the rule-breakers—species which challenge the norm.

Among these outliers includes our own species, Homo sapiens, which has evolved more than 20 times faster than all other mammal species, resulting in the massive brains that characterize humanity today. But humans are not the only species to buck this trend.

All groups of mammals demonstrated rapid bursts of change—both towards smaller and larger brain sizes. For example, bats very rapidly reduced their brain size when they first arose, but then showed very slow rates of change in relative brain size, suggesting there may be evolutionary constraints related to the demands of flight.

There are three groups of animals that showed the most pronounced rapid change in brain size: primates, rodents, and carnivores. In these three groups, there is a tendency for relative brain size to increase in time (the "Marsh-Lartet rule"*). This is not a trend universal across all mammals, as previously thought.

* a tendency for relative brain sizes to increase with time. But, as the study notes, this rule is not universally applicable across all mammals
part 1

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 11:41am

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 11:28am

First fossil chromosomes discovered
Scientists have discovered intact chromosomes preserved in the skin of a woolly mammoth (Mammuthus primigenius) that met its end some 50,000 years ago — a feat previously thought to be impossible. The team also revealed the spatial organization of the mammoth’s DNA molecules and the active genes in its skin, including one responsible for giving the animal its fuzzy appearance. The study is the first to report the 3D structure of an ancient genome.

https://www.cell.com/cell/fulltext/S0092-8674(24)00642-1?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867424006421%3Fshowall%3Dtrue

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 10:48am

The study pinpoints potential targets for preventing or treating muscle weakness related to brain inflammation. The researchers found that IL-6 activates what is called the JAK-STAT pathway in muscle, and this is what causes the reduced energy production of mitochondria.
Several therapeutics already approved by the FDA for other diseases can block this pathway. JAK inhibitors as well as several monoclonal antibodies against IL-6 are approved to treat various types of arthritis and manage other inflammatory conditions.

The researchers are not sure why the brain produces a protein signal that is so damaging to muscle function across so many different disease categories, though.
They speculate about possible reasons this process has stayed with us over the course of human evolution, despite the damage it does, it could be a way for the brain to reallocate resources to itself as it fights off disease. More research is  needed  to better understand this process and its consequences throughout the body.

Shuo Yang et al, Infection and chronic disease activate a systemic brain-muscle signaling axis, Science Immunology (2024). DOI: 10.1126/sciimmunol.adm7908. www.science.org/doi/10.1126/sciimmunol.adm7908

Part 2

Comment by Dr. Krishna Kumari Challa on July 13, 2024 at 10:45am

Scientists identify possible way to block muscle fatigue in long COVID, other diseases

Infections and neurodegenerative diseases cause inflammation in the brain. But for unknown reasons, patients with brain inflammation often develop muscle problems that seem to be independent of the central nervous system. Now, researchers  have revealed how brain inflammation releases a specific protein that travels from the brain to the muscles and causes a loss of muscle function.

The study, in fruit flies and mice, also identified ways to block this process, which could have implications for treating or preventing the muscle wasting sometimes associated with inflammatory diseases including bacterial infections, Alzheimer's disease and long COVID.

The study is published July 12 in the journal Science Immunology.

 The study suggests that when we get sick, messenger proteins from the brain travel through the bloodstream and reduce energy levels in skeletal muscle. This is more than a lack of motivation to move because we don't feel well. These processes reduce energy levels in skeletal muscle, decreasing the capacity to move and function normally.

To investigate the effects of brain inflammation on muscle function, the researchers modeled three different types of diseases—an E. coli bacterial infection, a SARS-CoV-2 viral infection and Alzheimer's.

When the brain is exposed to inflammatory proteins characteristic of these diseases, damaging chemicals called reactive oxygen species build up. The reactive oxygen species cause brain cells to produce an immune-related molecule called interleukin-6 (IL-6), which travels throughout the body via the bloodstream.

The researchers found that IL-6 in mice—and the corresponding protein in fruit flies—reduced energy production in muscles' mitochondria, the energy factories of cells.

Flies and mice that had COVID-associated proteins in the brain showed reduced motor function—the flies didn't climb as well as they should have, and the mice didn't run as well or as much as control mice.

The researchers saw similar effects on muscle function when the brain was exposed to bacterial-associated proteins and the Alzheimer's protein amyloid beta. They also saw evidence that this effect can become chronic. Even if an infection is cleared quickly, the reduced muscle performance remains many days longer in their experiments.

The bacterial brain infection meningitis is known to increase IL-6 levels and can be associated with muscle issues in some patients, for instance. Among COVID-19 patients, inflammatory SARS-CoV-2 proteins have been found in the brain during autopsy, and many long COVID patients report extreme fatigue and muscle weakness even long after the initial infection has cleared.

Patients with Alzheimer's disease also show increased levels of IL-6 in the blood as well as muscle weakness.

Part1

• ‹ Previous
• 1
• …
• 110
• 111
• 112
• 113
• 114
• …
• 999
• Next ›
• Page