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How did dogs get to the Americas? An ancient bone fragment holds clues

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How did dogs get to the Americas? An ancient bone fragment holds clues

The history of dogs has been intertwined, since ancient times, with that of the humans who domesticated them.

But how far back does that history go in the Americas, and which route did dogs use to enter this part of the world?

A new study led by the University at Buffalo provides insight into these questions. The research reports that a bone fragment found in Southeast Alaska belongs to a dog that lived in the region about 10,150 years ago. Scientists say the remains — a piece of a femur — represent the oldest confirmed remains of a domestic dog in the Americas.

DNA from the bone fragment holds clues about early canine history in this part of the world.

Researchers analyzed the dog’s mitochondrial genome, and concluded that the animal belonged to a lineage of dogs whose evolutionary history diverged from that of Siberian dogs as early as 16,700 years ago. The timing of that split coincides with a period when humans may have been migrating into North America along a coastal route that included Southeast Alaska.

The research will be published on Feb. 24 in the Proceedings of the Royal Society B. Charlotte Lindqvist, an evolutionary biologist from UB, was senior author of the study, which included scientists from UB and the University of South Dakota. The findings add to a growing body of knowledge about the migration of dogs into the Americas.


“We now have genetic evidence from an ancient dog found along the Alaskan coast. Because dogs are a proxy for human occupation, our data help provide not only a timing but also a location for the entry of dogs and people into the Americas. Our study supports the theory that this migration occurred just as coastal glaciers retreated during the last Ice Age,” says Lindqvist, PhD, associate professor of biological sciences in the UB College of Arts and Sciences. “There have been multiple waves of dogs migrating into the Americas, but one question has been, when did the first dogs arrive? And did they follow an interior ice-free corridor between the massive ice sheets that covered the North American continent, or was their first migration along the coast?”

“”The fossil record of ancient dogs in the Americas is incomplete, so any new remains that are found provide important clues,” says Flavio Augusto da Silva Coelho, a UB PhD student in biological sciences, and one of the paper’s first authors. “Before our study, the earliest ancient American dog bones that had their DNA sequenced were found in the U.S. Midwest.”

A surprise finding from a large collection of bones

Lindqvist’s team did not set out to study dogs. The scientists came across the femur fragment while sequencing DNA from a collection of hundreds of bones excavated years before in Southeast Alaska by researchers including Timothy Heaton, PhD, professor of earth sciences at the University of South Dakota.

“”This all started out with our interest in how Ice Age climatic changes impacted animals’ survival and movements in this region,” Lindqvist says. “”Southeast Alaska might have served as an ice-free stopping point of sorts, and now — with our dog — we think that early human migration through the region might be much more important than some previously suspected.””

The bone fragment, originally thought to come from a bear, was quite small, but when the DNA was studied, the team realized it was from a dog, Lindqvist says.


After this surprise discovery, the scientists compared the bone’s mitochondrial genome to those of other ancient and modern dogs. This analysis showed that the Southeast Alaskan dog shared a common ancestor about 16,000 years ago with American canines that lived before the arrival of European colonizers, Lindqvist says. (Mitochondrial DNA, inherited from the mother, represents a small fraction of an organism’s complete DNA, so sequencing a complete nuclear genome could provide further details if that material can be extracted.)

Of interest, carbon isotope analysis on the bone fragment indicates that the ancient Southeast Alaskan dog likely had a marine diet, which may have consisted of foods such as fish and scraps from seals and whales.

The research adds depth to the layered history of how dogs came to populate the Americas. As Lindqvist notes, canines did not arrive all at once. For example, some Arctic dogs arrived later from East Asia with the Thule culture, while Siberian huskies were imported to Alaska during the Gold Rush. Other dogs were brought to the Americas by European colonizers.

The new study sharpens the debate on dog and human migration into the Americas.

“Our early dog from Southeast Alaska supports the hypothesis that the first dog and human migration occurred through the Northwest Pacific coastal route instead of the central continental corridor, which is thought to have become viable only about 13,000 years ago,” Coelho notes.

The research was funded by the National Science Foundation. In addition to Lindqvist, Coelho and Heaton, authors of the new paper in Proceedings of the Royal Society B included Stephanie Gill and Crystal Tomlin.

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Bedtime battles: 1 in 4 parents say their child can’t go to sleep because they’re worried or anxious

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How did dogs get to the Americas? An ancient bone fragment holds clues


Many bedtime battles stem from children’s after dark worries, suggests a new national poll.

And while most families have bedtime rituals to help their little ones ease into nighttime, many rely on strategies that may increase sleep challenges long term, according to the University of Michigan Health C.S. Mott Children’s Hospital National Poll on Children’s Health.

Overall, one in four parents describe getting their young child to bed as difficult — and these parents are less likely to have a bedtime routine, more likely to leave on a video or TV show, and more likely to stay with their child until they’re asleep.

“Our report reinforces the common struggle of getting young children to sleep. When this transition to bedtime becomes a nightly conflict, some parents may fall into habits that work in the moment but could set them up for more sleep issues down the road,” said Mott Poll co-director Sarah Clark, M.P.H.

“Establishing a consistent bedtime routine is crucial. When children don’t get enough rest, it can impact their physical development, emotional regulation and behavior.”

Nearly one in five parents say they have given their kids melatonin to help with sleep while a third stay in the room until their child completely dozes off, according to the nationally representative poll that includes responses from 781 parents of children ages one to six surveyed in February.

Nighttime worries interfere with sleep

Parents share common reasons behind bedtime struggles, with nearly a quarter saying their child’s sleep is often or occasionally delayed due to being worried or anxious.

A particular challenge, parents say, is when children don’t stay asleep. More than a third of parents say their child wakes up upset or crying, with more than 40% saying their child moves to their parents’ bed and about 30% saying children insist that the parent sleep in their room.

“Many young children go through stages when they become scared of the dark or worry that something bad might happen, causing them to delay bedtime or become distressed by parents leaving the room. Bad dreams or being awakened in the middle of the night can also disrupt sleep,” Clark said.

“Although this is a normal part of a child’s development, it can be frustrating when parents already feel tired themselves at the end of the day. Parents should find a balance between offering reassurance and comfort while maintaining some boundaries that help ensure everyone — both kids and adults — get adequate sleep.”

More findings from the report, plus Clark’s recommendations for helping young children fall and stay asleep:

Stick to a regular bedtime routine

Most parents polled report having a bedtime routine for their child, often including brushing teeth, reading bedtime stories and/or bathing. Less than half also say their child has a drink of water or snack, turns off devices, prays and talks about their day.

Other bedtime habits include holding a blanket or stuff animal or sucking a pacifier or fingers.

Not only does having a consistent bedtime routine help make the nighttime transition smoother, Clark says, it also provides one-on-one time, allowing the child to get their parent’s full attention.

“A predictable bedtime routine provides a sense of security and comfort and signals to the child that it’s time to slow down,” she said.

“Knowing what to expect next can reduce anxiety and help children feel safe and relaxed. Having this dedicated time with parents also promotes bonding and emotional connection, creating positive associations with bedtime.”

Nearly two-thirds of parents also said children staying up to play was a major factor in delaying sleep. Clark says, highlighting the need to wind down at least an hour before bed.

Promote an environment conducive to sleep

A little less than half of parents polled say their child sleeps in their own bedroom while less than a quarter share a bedroom with siblings or in the parents’ bedroom. One in 10 kids spend part the night in their own bedroom and part of the night with parents.

More than two-fifths of parents polled said noise from other rooms interfered with their child’s sleep.

“The sleep environment can have a major effect on a child’s sleep quality, including getting to sleep and staying asleep through the night,” Clark said.

“When possible, children should have their own bed in a room that is quiet, without a lot of noise from other family members.”

Many parents polled also use a nightlight or crack the bedroom door so the child isn’t in complete darkness, Clark says, but parents should make sure the light does not shine directly at the child’s face.

Some parents also play calming music or stories to help their child go to sleep, while others use a white noise machine or app. However, Clark cautions to keep white noise machines at no more than 50 decibels and placed at least seven feet from the child’s bed to prevent unintended damage to the child’s hearing.

Talk to a doctor before using aids like melatonin

Many types of melatonin products are advertised as being appropriate for children but these products have not undergone rigorous testing for safety and effectiveness, and their side effects and long term impact on a child’s growth and development are unknown, Clark says.

“Although melatonin is a natural hormone that regulates sleep-wake cycles and may be fine to use occasionally, parents shouldn’t rely on it as a primary sleep aid,” Clark said.

“Parents who are considering giving melatonin to their young child should consult with their pediatrician to discuss options and rule out other causes of sleep problems first.”

If using melatonin, parents should also start with the lowest dose possible.

In addition, it’s important to keep electronics such as tablets or televisions out of children’s bedroom, as the blue light emitted by many of these screens interferes with the natural production of melatonin.

Offer comfort but enforce boundaries

Parents can help ease little ones’ anxiety by allowing extra time to let them talk about their day, which might draw out specific worries and give parents a chance to provide compassion and reassurance, Clark said.

Rather than remaining in the room, parents can also offer to check on the child every few minutes, which acknowledges the child’s fears and offers a reassuring presence, but still maintains a calm sleep environment and promotes sleep independence.

“Families can incorporate comforting rituals to help transform nighttime fears into a calming experience,” Clark said.

Have a consistent approach when children wake up in the night

Some children are prone to vivid dreams or nightmares and may have difficulty getting back to sleep. Parents should decide on their approach to this situation and stick with it, Clark says, whether it’s taking the child back to bed or allowing them to stay in the parents’ room.

“Being consistent in carrying out that approach will help the child adjust and be more likely to return to sleep,” Clark said.

Ease into changes in sleep patterns, such as dropping naps

For young children, a major sleep-related transition is discontinuing daytime naps. In general, children ages one to two should get 11-14 hours of sleep with naps while the amount of recommended sleep decreases slightly from ages three to six.

If children are taking longer to fall asleep at nap time, resisting naps or suddenly having difficulty falling asleep at night or waking up earlier than usual in the morning, it may be time to drop the nap, Clark says.

“Parents may need to adjust sleep routines gradually to transition to changes to a child’s sleep patterns,” Clark said.

Other changes that can affect a child’s sleep include transitioning from a crib to a toddler bed, starting school, having a change in their daytime routine, or being outdoors for longer than usual.



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Direct evidence found for dairy consumption in the Pyrenees in the earliest stages of the Neolithic

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How did dogs get to the Americas? An ancient bone fragment holds clues


A joint study conducted by the Universitat Autònoma de Barcelona, the University of Zaragoza and the University of Strasbourg on the remains of the Chaves and Puyascada caves, both located in the province of Huesca, Spain, yields the first direct proof of the consumption and processing of dairy products in the Pyrenees already at the start of the Neolithic period, approximately 7,500 years ago, as well as the consumption of pig. The results lead to doubts about the belief that these products were first used much later in the Pyrenean mountain range.

The analysis of the content and use of prehistoric vessels has become a valuable source of information on the food patterns and subsistence practices of past societies. A research conducted on the materials found at the Huescan sites of Cueva de Chaves (Bastaràs), at 640 metres above sea level, and at Espluga de la Puyascada (La Fueva), at 1,300 metres above sea level, in a strictly Pyrenean mountain region, now has yielded the first direct evidence of dairy product consumption and processing in the Pyrenees during the earliest stages of the Neolithic.

The study was conducted by prehistorians from the Universitat Autònoma de Barcelona (UAB) and the University of Zaragoza, and chemists from the University of Strasbourg, France, on materials on display at the Huesca Museum. The findings have now been published in the journal Archaeological and Anthropological Sciences.

The research was conducted through a combination of techniques used to identify organic residues and the isotopic characterisation of fatty acids to determine animal origin, as well as data obtained of the morphology and functionality of ceramics and the archaeozoological studies of both sites.

The analysis of organic residues preserved in the argillaceous matrix of the interior of 36 ceramic vessels indicates that 7,500 years ago dairy products were already processed and consumed in the Central Pyrenees. The correlation between the residues of dairy fats and the different forms of the pottery suggests, moreover, that all the processes (preparation, consumption and storage) were carried out in both settlements.

This “questions previous considerations in which dairy consumption in the Pyrenees was thought to have begun much later,” points out Nàdia Tarifa, researcher from the University of Strasbourg when this study was conducted, and lead autor of the paper. “It was always thought that prehistoric social dynamics in mountainous regions were slower or ‘less evolved’ than in coastal regions. Our study adds solid proof to previous faunistic studies conducted in both sites, which had pointed to dairy farming in these mountainous regions at the very early stages of the Neolithic period,” Tarifa states.

The study also shows how pig-derived products may have been processed or stored in ceramic vessels at both sites, which would indicate the importance of this species for the early mountain farming economies. In contrast to the results for milk, researchers also observed variations between the two sites in terms of the exploitation of meat from ruminants and pigs, with a predominance of the former in Espluga de la Puyascada and the latter in Cueva de Chaves. These differences could be related to the characteristics of the settlements and their surroundings, and to the methods of meat processing.

The researchers also identified residues from processed vegetables, as well as from pine resin. The latter substance would have been used to waterproof the inside of the vessels.

The results support the idea that in the early Neolithic period in the Pyrenean area there was a mixed economy based on integrated agriculture and livestock farming (in which one supported the other), with sheep herds as the main source of meat and milk.

“Our findings provide a better understanding of consumption habits and the technological use of resources in the early Neolithic period in the Pyrenees and open up new avenues of research to deepen our understanding of the social and economic dynamics of ancient societies, especially in mountainous areas,” says Alejandro Sierra, researcher at the UAB and co-author of the study.



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A high-fat diet may fuel anxiety

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How did dogs get to the Americas? An ancient bone fragment holds clues


When stressed out, many of us turn to junk food for solace. But new University of Colorado Boulder research suggests this strategy may backfire.

The study found that in animals, a high-fat diet disrupts resident gut bacteria, alters behavior and, through a complex pathway connecting the gut to the brain, influences brain chemicals in ways that fuel anxiety.

“Everyone knows that these are not healthy foods, but we tend to think about them strictly in terms of a little weight gain,” said lead author Christopher Lowry, a professor of integrative physiology at CU Boulder. “If you understand that they also impact your brain in a way that can promote anxiety, that makes the stakes even higher.”

Lowry’s team divided adolescent rats into two groups: Half got a standard diet of about 11% fat for nine weeks; the others got a high-fat diet of 45% fat, consisting mostly of saturated fat from animal products.

The typical American diet is about 36% fat, according to the Centers for Disease Control and Prevention.

Throughout the study, the researchers collected fecal samples and assessed the animals’ microbiome, or gut bacteria. After nine weeks, the animals underwent behavioral tests.

When compared to the control group, the group eating a high-fat diet, not surprisingly, gained weight. But the animals also showed significantly less diversity of gut bacteria. Generally speaking, more bacterial diversity is associated with better health, Lowry explained. They also hosted far more of a category of bacteria called Firmicutes and less of a category called Bacteroidetes. A higher Firmicutes to Bacteroidetes ratio has been associated with the typical industrialized diet and with obesity.

The high-fat diet group also showed higher expression of three genes (tph2, htr1a, and slc6a4) involved in production and signaling of the neurotransmitter serotonin — particularly in a region of the brainstem known as the dorsal raphe nucleus cDRD, which is associated with stress and anxiety.

While serotonin is often billed as a “feel-good brain chemical,” Lowry notes that certain subsets of serotonin neurons can, when activated, prompt anxiety-like responses in animals. Notably, heightened expression of tph2, or tryptophan hydroxylase, in the cDRD has been associated with mood disorders and suicide risk in humans.

“To think that just a high-fat diet could alter expression of these genes in the brain is extraordinary,” said Lowry. “The high-fat group essentially had the molecular signature of a high anxiety state in their brain.”

Lowry suspects that an unhealthy microbiome compromises the gut lining, enabling bacteria to slip into the body’s circulation and communicate with the brain via the vagus nerve, a pathway from the gastrointestinal tract to the brain.

“If you think about human evolution, it makes sense,” Lowry said. “We are hard-wired to really notice things that make us sick so we can avoid those things in the future.”

Lowry stresses that not all fats are bad, and that healthy fats like those found in fish, olive oil, nuts and seeds can be anti-inflammatory and good for the brain.

His advice: Eat as many different kinds of fruits and vegetables as possible, add fermented foods to your diet to support a healthy microbiome and lay off the pizza and fries. Also, if you do have a hamburger, add a slice of avocado. Some research shows that good fat can counteract some of the bad.



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