How the Western diet has derailed our evolution

Moises Velesquez-Manoff writes: For the microbiologist Justin Sonnenburg, that career-defining moment — the discovery that changed the trajectory of his research, inspiring him to study how diet and native microbes shape our risk for disease — came from a village in the African hinterlands.

A group of Italian microbiologists had compared the intestinal microbes of young villagers in Burkina Faso with those of children in Florence, Italy. The villagers, who subsisted on a diet of mostly millet and sorghum, harbored far more microbial diversity than the Florentines, who ate a variant of the refined, Western diet. Where the Florentine microbial community was adapted to protein, fats, and simple sugars, the Burkina Faso microbiome was oriented toward degrading the complex plant carbohydrates we call fiber.

Scientists suspect our intestinal community of microbes, the human microbiota, calibrates our immune and metabolic function, and that its corruption or depletion can increase the risk of chronic diseases, ranging from asthma to obesity. One might think that if we coevolved with our microbes, they’d be more or less the same in healthy humans everywhere. But that’s not what the scientists observed. [Continue reading…]


The antibiotic apocalypse has begun

BBC News reports: The world is on the cusp of a “post-antibiotic era”, scientists have warned after finding bacteria resistant to drugs used when all other treatments have failed.

They identified bacteria able to shrug off the drug of last resort – colistin – in patients and livestock in China.

They said that resistance would spread around the world and raised the spectre of untreatable infections.
It is likely resistance emerged after colistin was overused in farm animals.

Bacteria becoming completely resistant to treatment – also known as the antibiotic apocalypse – could plunge medicine back into the dark ages. [Continue reading…]


In a society where everyone is ready to defend the common good, corruption doesn’t pay

Suzanne Sadedin writes: By making a few alterations to the composition of the justice system, corrupt societies could be made to transition to a state called ‘righteousness’. In righteous societies, police were not a separate, elite order. They were everybody. When virtually all of society stood ready to defend the common good, corruption didn’t pay.

Among honeybees and several ant species, this seems to be the status quo: all the workers police one another, making corruption an unappealing choice. In fact, the study showed that even if power inequalities later re-appeared, corruption would not return. The righteous community was extraordinarily stable.

Not all societies could make the transition. But those that did would reap the benefits of true, lasting harmony. An early tribe that made the transition to righteousness might out-compete more corrupt rivals, allowing righteousness to spread throughout the species. Such tribal selection is uncommon among animals other than eusocial insects, but many researchers think it could have played a role in human evolution. Hunter-gatherer societies commonly tend toward egalitarianism, with social norms enforced by the whole group rather than any specially empowered individuals. [Continue reading…]


Climate change implicated in death of more than half an entire species of endangered antelopes in less than a month

Carl Zimmer writes: A mysterious die-off of endangered antelopes last spring in Central Asia was even more extensive than originally thought, killing more than half of the entire species in less than a month, scientists have found.

“I’ve worked in wildlife disease all my life, and I thought I’d seen some pretty grim things,” Richard A. Kock, of the Royal Veterinary College in London, said in a telephone interview. “But this takes the biscuit.”

At a scientific meeting last week in Tashkent, Uzbekistan, Dr. Kock and his colleagues reported that they had narrowed down the possible culprits. Climate change and stormy spring weather, they said, may have transformed harmless bacteria carried by the antelopes, called saigas, into lethal pathogens.

It is a scenario that deeply worries scientists. “It’s not going to be something the species can survive,” Dr. Kock said. “If there are weather triggers that are broad enough, you could actually have extinction in one year.” [Continue reading…]


How did complex creatures evolve from simple single-celled organisms?

Emily Singer writes: In September 2014, Christa Schleper embarked on an unusual hunting expedition in Slovenia. Instead of seeking the standard quarry of deer or wild boar, Schleper was in search of Lokiarchaeota, or Loki, a newly discovered group of organisms first identified near deep-sea vents off the coast of Norway. The simple, single-celled creatures have captured scientists’ interest because they are unlike any other organism known to science. They belong to an ancient group of creatures known as archaea, but they seem to share some features with more complex life-forms, including us.

Though little is known about Loki, scientists hope that it will help to resolve one of biology’s biggest mysteries: how life transformed from simple single-celled organisms to the menagerie of complex life known as eukaryotes — a category that includes everything from yeast to azaleas to elephants. “Next to the origins of life, there’s probably no bigger mystery in the history of life,” said John Archibald, an evolutionary biologist at Dalhousie University in Nova Scotia.

The jump from single cells to complex creatures is so puzzling because it represents an enormous evolutionary gulf. “How do you make a eukaryote, that’s a big question,” said Schleper, a microbiologist at the University of Vienna in Austria. “It’s a huge transition.”

Though single-celled organisms blanket the Earth and are capable of impressive biochemistry — some can eat nuclear waste, for example — their structure and shape remain simple. Cells from animals, plants and fungi, which make up the eukaryotes, are much more sophisticated. They possess a suite of features lacking in their simpler brethren: a nucleus that houses DNA; an energy-producing device known as the mitochondrion; and molecular architecture, known as the cytoskeleton, that controls cell shape and movement.

Most biologists agree that at some point around two billion years ago, one featureless cell swallowed another, and the two began to work together as one. But the details of this process — whether this symbiosis jump-started an evolutionary process, or whether it happened midway along the path to eukaryotes — continue to drive huge disputes in the field. [Continue reading…]


The African lion: What faster decline of apex predator means for ecosystems

By Matt Hayward, Bangor University

There is nothing as awe-inspiring as watching the brutal power of a lion capturing its prey. At close range, their throaty roars thump through your body, raising a cold sweat triggered by the fear of what these animals are capable of doing now, and what they once did to our ancestors. They are the most majestic animals left on our planet, and yet we are currently faced with the very real possibility that they will be functionally extinct within our lifetime.

In fact, lion populations throughout much of Africa are heading towards extinction more rapidly than previously thought, according to new research by Oxford biologist Hans Bauer and colleagues, published in PNAS. The team looked at 47 sites with credible and repeated lion surveys since 1990, and found they were declining everywhere in Africa aside from four countries: Botswana, Namibia, South Africa and Zimbabwe.

West and Central African lion populations have a 67% chance of halving in size in just two decades, and East African populations a 37% chance. Almost all large lion populations that once exceeded 500 individuals outside of southern Africa are declining. These declines in Africa’s apex predator occur at the same time that the continent’s mega-herbivores are also plummeting.

[Read more…]


Competition in Cambrian seas 542 million years ago helped cause an explosion in animal diversity

Brooke Borel writes: Battles fought 542 million years before today helped fuel a blast that brought humans and most animals into existence. The great Cambrian Explosion was a period of unprecedented one-upmanship. Beastly claws crushed through thin skin, and soft-bodied creatures evolved shells shaped like scythes, sickles, and shields.

For about a billion years prior, the cells and genes that would later create animals were evolving in microscopic organisms who inhabited the oceans of Earth. These essential molecular changes may only be inferred today because they’re not preserved in fossils. The earliest traces of animals, about 580 million years old, appear soft, with no sign of claws, teeth, limbs, or brains. Then, within 54 million years (a relative blink but still, 270 times the duration of humans’ existence thus far), most of the main animal groups around today originated. This rapid rate of increase in animal architectures has never since been repeated.

A simple species count does not do justice to the power of the Cambrian Explosion. Species have continuously formed over time. A new type of moth may have antennae that are furrier than its sisters; a new species of dinosaur may be distinguished by clawed wings and vicious front fangs. But a new phylum — a major branch on the tree of life, the upper-level ranking that separates an insect from a pterodactyl — is rarely born.

Most of today’s 30 to 40 animal phyla originated in the Cambrian, and have persisted through time with hundreds of variations on a theme. [Continue reading…]


Old and new: How the brain evokes a sense of familiarity

Science News reports: It’s happened to all of us at one time or another: You’re walking through a crowd, and suddenly a face seems incredibly familiar — so much so that you do a double-take. Who is that? How do you know them? You have no idea, but something about their face nags at you. You know you’ve seen it before.

The reason you know that face is in part because of your perirhinal cortex. This is an area of the brain that helps us to determine familiarity, or whether we have seen an object before. A new study of brain cells in this area finds that firing these neurons at one frequency makes the brain treat novel images as old hat. But firing these same neurons at another frequency can make the old new again.

“Novelty and familiarity are both really important,” says study coauthor Rebecca Burwell, a neuroscientist at Brown University in Providence, R.I. “They are important for learning and memory and decision making.” Finding a cache of food and knowing it is new could be useful for an animal’s future. So is recognizing a familiar place where the pickings were good in the past.

But knowing that something is familiar is not quite the same thing as knowing what that thing is. “You’re in a crowd and you see a familiar face, and there’s a feeling,” Burwell explains. “You can’t identify them, you don’t know where you met them, but there’s a sense of familiarity.” It’s different from recalling where you met the person, or even who the person is. This is a sense at the base of memory. And while scientists knew the perirhinal cortex was involved in this sense of familiarity, how that feeling of new or old was coded in the brain wasn’t fully understood. [Continue reading…]


Video: The hidden life of the cell


Human Genome Project: Twenty-five years of big biology

Eric D. Green, James D. Watson& Francis S. Collins write: Twenty-five years ago, the newly created US National Center for Human Genome Research (now the National Human Genome Research Institute; NHGRI), which the three of us have each directed, joined forces with US and international partners to launch the Human Genome Project (HGP). What happened next represents one of the most historically significant scientific endeavours: a 13-year quest to sequence all three billion base pairs of the human genome.

Even just a few years ago, discussions surrounding the HGP focused mainly on what insights the project had brought or would bring to our understanding of human disease. Only now is it clear that, as well as dramatically accelerating biomedical research, the HGP initiated a new way of doing science.

As biology’s first large-scale project, the HGP paved the way for numerous consortium-based research ventures. The NHGRI alone has been involved in launching more than 25 such projects since 2000. These have presented new challenges to biomedical research — demanding, for instance, that diverse groups from different countries and disciplines come together to share and analyse vast data sets. [Continue reading…]

The Independent reports: The most comprehensive study of the human genome has discovered that a sizeable minority of people are walking around with some of their genes missing without any apparent ill-effects, scientists have found.

A project to sequence and analyse the entire genetic code of more than 2,500 people drawn from 26 different ethnic populations from around the world has revealed that some genes do not seem to be as essential for health and life as previously believed.

The finding is just one to have emerged from the 1,000 Genomes Project set up in 2008 to study the genetic variation in at least this number of people in order to understand the variety of DNA types within the human population, the researchers said. [Continue reading…]


Imagining strange new lifeforms could help us discover our own origins

By Michael Page, University of Huddersfield

From the earliest of times, philosophers and scientists have tried to understand the relationship between animate and inanimate matter. But the origin of life remains one of the major scientific riddles to be solved.

The building blocks of life as we know it essentially consist of four groups of chemicals: proteins, nucleic acids, lipids (fats) and carbohydrates. There was much excitement about the possibility of finding amino acids (the ingredients for proteins) on comets or distant planets because some scientists believe that life on Earth, or at least its building blocks, may have originally come from outer space and been deposited by meteorites.

But there are now extensive examples of how natural processes on Earth can convert simple molecules into these building blocks. Scientists have demonstrated in the lab how to make amino acids, simple sugars, lipids and even nucleotides – the basic units of DNA – from very simple chemicals, under conditions that could have existed on early earth. What still eludes them is the point in the process when a chemical stew becomes an organism. How did the first lifeforms become alive?

[Read more…]


Which species will survive the Earth’s sixth mass extinction?

By Matthew Wills, University of Bath

Scientists recently suggested that the Earth’s sixth mass extinction has begun. As terrifying as that sounds, surely humans are too smart and too important to get wiped out? Palaeontologists have long tried to shed light on this question by looking for general rules that might predict the survival of a species.

While this is not exactly a straightforward exercise, research so far indicates that the odds are not in our favour.

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Paleogenetics is helping to solve the great mystery of prehistory: How did humans spread out over the earth?

Jacob Mikanowski writes: Most of human history is prehistory. Of the 200,000 or more years that humans have spent on Earth, only a tiny fraction have been recorded in writing. Even in our own little sliver of geologic time, the 12,000 years of the Holocene, whose warm weather and relatively stable climate incubated the birth of agriculture, cities, states, and most of the other hallmarks of civilisation, writing has been more the exception than the rule.

Professional historians can’t help but pity their colleagues on the prehistoric side of the fence. Historians are accustomed to drawing on vast archives, but archaeologists must assemble and interpret stories from scant material remains. In the annals of prehistory, cultures are designated according to modes of burial such as ‘Single Grave’, or after styles of arrowhead, such as ‘Western Stemmed Point’. Whole peoples are reduced to styles of pottery, such as Pitted Ware, Corded Ware or Funnel Beaker, all of them spread across the map in confusing, amoeba-like blobs.

In recent years, archaeologists have become reluctant to infer too much from assemblages of ceramics, weapons and grave goods. For at least a generation, they have been drilled on the mantra that ‘pots are not people’. Material culture is not a proxy for identity. Artefacts recovered from a dig can provide a wealth of information about a people’s mode of subsistence, funeral rites and trade contacts, but they are not a reliable guide to their language or ethnicity – or their patterns of migration.

Before the Second World War, prehistory was seen as a series of invasions, with proto-Celts and Indo-Aryans swooping down on unsuspecting swaths of Europe and Asia like so many Vikings, while megalith builders wandered between continents in indecisive meanders. After the Second World War, this view was replaced by the processual school, which attributed cultural changes to internal adaptations. Ideas and technologies might travel, but people by and large stayed put. Today, however, migration is making a comeback.

Much of this shift has to do with the introduction of powerful new techniques for studying ancient DNA. The past five years have seen a revolution in the availability and scope of genetic testing that can be performed on prehistoric human and animal remains. Ancient DNA is tricky to work with. Usually it’s degraded, chemically altered and cut into millions of short fragments. But recent advances in sequencing technology have made it possible to sequence whole genomes from samples reaching back thousands, and tens of thousands, of years. Whole-genome sequencing yields orders of magnitude more data than organelle-based testing, and allows geneticists to make detailed comparisons between individuals and populations. Those comparisons are now illuminating new branches of the human family tree. [Continue reading…]


In defence of bats: Beautifully designed mammals that should be left in peace

By Daniel Horton, University of Surrey

As a wildlife veterinarian, I often get asked about bats. I like bats, and I am always eager to talk about how interesting they are. Unfortunately the question is often not about biology but instead “what should I do about the ones in my roof?”.

With some unique talents and remarkable sex lives, bats are actually one of the most interesting, diverse and misunderstood groups of animals. Contrary to popular belief, they are beautiful creatures. Not necessarily in the cuddly, human-like sense – although some fruit bats with doey brown eyes and button noses could be considered so – but they are beautifully designed.

This couldn’t be illustrated better than by the discovery of the oldest known complete bat fossil, more than 53 million-years-old yet with a similar wing design to those flying around today. To put it in perspective, 50m years ago our ancestors were still swinging from the trees and would certainly not be recognised as human. But even then bats already had the combination of thin, long forearms and fingers covered by an extremely thin, strong membrane, which allowed them to master the art of powered, agile flight.

A flying fox shows off its 50 million-year-old wing design.
Duncan PJ, CC BY-SA

Soon afterwards, fossils record another game-changing adaptation in the evolution of most bats, and that is the ability to accurately locate prey using sound (what we call echolocation). These two adaptations early in their history gave bats an evolutionary edge compared to some other mammals, and allowed them to diversify into almost all habitats, on every continent except Antarctica.

[Read more…]


How a child’s cells become scattered throughout its mother’s body

Carl Zimmer writes: Recently a team of pathologists at Leiden University Medical Center in the Netherlands carried out an experiment that might seem doomed to failure.

They collected tissue from 26 women who had died during or just after pregnancy. All of them had been carrying sons. The pathologists then stained the samples to check for Y chromosomes.

Essentially, the scientists were looking for male cells in female bodies. And their search was stunningly successful.

As reported last month in the journal Molecular Human Reproduction, the researchers found cells with Y-chromosomes in every tissue sample they examined. These male cells were certainly uncommon — at their most abundant, they only made up about 1 in every 1,000 cells. But male cells were present in every organ that the scientists studied: brains, hearts, kidneys and others.

In the 1990s, scientists found the first clues that cells from both sons and daughters can escape from the uterus and spread through a mother’s body. They dubbed the phenomenon fetal microchimerism, after the chimera, a monster from Greek mythology that was part lion, goat and dragon.

But fetal cells don’t just drift passively. Studies of female mice show that fetal cells that end up in their hearts develop into cardiac tissue. “They’re becoming beating heart cells,” said Dr. J. Lee Nelson, an expert on microchimerism at the Fred Hutchinson Cancer Research Center in Seattle.

The new study suggests that women almost always acquire fetal cells each time they get pregnant. They have been detected as early as seven weeks into a pregnancy. In later years, the cells may disappear from their bodies, but sometimes the cells settle in for a lifetime. [Continue reading…]