Lilian Dove, Brown University

A surprising technique has helped scientists observe how Earth's oceans are changing, and it's not using specialized robots or artificial intelligence. It's tagging seals.

Several species of seals live around and on Antarctica and regularly dive more than 100 meters in search of their next meal. These seals are experts at swimming through the vigorous ocean currents that make up the Southern Ocean. Their tolerance for deep waters and ability to navigate rough currents make these adventurous creatures the perfect research assistants to help oceanographers like my colleagues and me study the Southern Ocean.

Seal sensors

Researchers have been attaching tags to the foreheads of seals for the past two decades to collect data in remote and inaccessible regions. A researcher tags the seal during mating season, when the marine mammal comes to shore to rest, and the tag remains attached to the seal for a year.

A researcher glues the tag to the seal's head – tagging seals does not affect their behavior. The tag detaches after the seal molts and sheds its fur for a new coat each year.

The tag collects data while the seal dives and transmits its location and the scientific data back to researchers via satellite when the seal surfaces for air.

First proposed in 2003, seal tagging has grown into an international collaboration with rigorous sensor accuracy standards and broad data sharing. Advances in satellite technology now allow scientists to have near-instant access to the data collected by a seal.

New scientific discoveries aided by seals

The tags attached to seals typically carry pressure, temperature and salinity sensors, all properties used to assess the ocean's rising temperatures and changing currents. The sensors also often contain chlorophyll fluorometers, which can provide data about the water's phytoplankton concentration.

Phytoplankton are tiny organisms that form the base of the oceanic food web. Their presence often means that animals such as fish and seals are around.

The seal sensors can also tell researchers about the effects of climate change around Antarctica. Approximately 150 billion tons of ice melts from Antarctica every year, contributing to global sea-level rise. This melting is driven by warm water carried to the ice shelves by oceanic currents.

With the data collected by seals, oceanographers have described some of the physical pathways this warm water travels to reach ice shelves and how currents transport the resulting melted ice away from glaciers.

Seals regularly dive under sea ice and near glacier ice shelves. These regions are challenging, and can even be dangerous, to sample with traditional oceanographic methods.

Across the open Southern Ocean, away from the Antarctic coast, seal data has also shed light on another pathway causing ocean warming. Excess heat from the atmosphere moves from the ocean surface, which is in contact with the atmosphere, down to the interior ocean in highly localized regions. In these areas, heat moves into the deep ocean, where it can't be dissipated out through the atmosphere.

The ocean stores most of the heat energy put into the atmosphere from human activity. So, understanding how this heat moves around helps researchers monitor oceans around the globe.

Seal behavior shaped by ocean physics

The seal data also provides marine biologists with information about the seals themselves. Scientists can determine where seals look for food. Some regions, called fronts, are hot spots for elephant seals to hunt for food.

In fronts, the ocean's circulation creates turbulence and mixes water in a way that brings nutrients up to the ocean's surface, where phytoplankton can use them. As a result, fronts can have phytoplankton blooms, which attract fish and seals.

Scientists use the tag data to see how seals are adapting to a changing climate and warming ocean. In the short term, seals may benefit from more ice melt around the Antarctic continent, as they tend to find more food in coastal areas with holes in the ice. Rising subsurface ocean temperatures, however, may change where their prey is and ultimately threaten seals' ability to thrive.

Seals have helped scientists understand and observe some of the most remote regions on Earth. On a changing planet, seal tag data will continue to provide observations of their ocean environment, which has vital implications for the rest of Earth's climate system.

Lilian Dove, Postdoctoral Fellow of Oceanography, Brown University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

John A. Lucey, University of Wisconsin-Madison

Cheese is a relatively simple food. It's made with milk, enzymes – these are proteins that can chop up other proteins – bacterial cultures and salt. Lots of complex chemistry goes into the cheesemaking process, which can determine whether the cheese turns out soft and gooey like mozzarella or hard and fragrant like Parmesan.

In fact, humans have been making cheese for about 10,000 years. Roman soldiers were given cheese as part of their rations. It is a nutritious food that provides protein, calcium and other minerals. Its long shelf life allows it to be transported, traded and shipped long distances.

I am a food scientist at the University of Wisconsin who has studied cheese chemistry for the past 35 years.

In the U.S., cheese is predominantly made with cow's milk. But you can also find cheese made with milk from other animals like sheep, goats and even water buffalo and yak.

Unlike with yogurt, another fermented dairy product, cheesemakers remove whey – which is water – to make cheese. Milk is about 90% water, whereas a cheese like cheddar is less than about 38% water.

Removing water from milk to make cheese results in a harder, firmer product with a longer shelf life, since milk is very perishable and spoils quickly. Before the invention of refrigeration, milk would quickly sour. Making cheese was a way to preserve the nutrients in milk so you could eat it weeks or months in the future.

How is cheese made?

All cheesemakers first pump milk into a cheese vat and add a special enzyme called rennet. This enzyme destabilizes the proteins in the milk – the proteins then aggregate together and make a gel. The cheesemaker is essentially turning milk from a liquid into a gel.

After anywhere from 10 minutes to an hour, depending on the type of cheese, the cheesemaker cuts this gel, typically into cubes. Cutting the gel helps some of the whey, or water, separate from the cheese curd, which is made of aggregated milk and looks like a yogurt gel. Cutting the gel into cubes lets some water escape from the newly cut surfaces through small pores, or openings, in the gel.

The cheesemaker's goal is to remove as much whey and moisture from the curd as they need to for their specific recipe. To do so, the cheesemaker might stir or heat up the curd, which helps release whey and moisture. Depending on the type of cheese made, the cheesemaker will drain the whey and water from the vat, leaving behind the cheese curds.

For a harder cheese like cheddar, the cheesemaker adds salt directly to the curds while they're still in the vat. Salting the curds expels more whey and moisture. The cheesemaker then packs the curds together in forms or hoops – these are containers that help shape the curds into a block or wheel and hold them there – and places them under pressure. The pressure squeezes the curds in these hoops, and they knit together to form a solid block of cheese.

Cheesemakers salt other cheeses, like mozzarella, by placing them in a salt solution called a brine. The cheese block or wheel floats in a brine tank for hours, days or even weeks. During that time, the cheese absorbs some of the salt, which adds flavor and protects against unwanted bacterial or pathogen growth.

Cheese is a living, fermented food

While the cheesemaker is completing all these steps, several important bacterial processes are occurring. The cheesemaker adds cheese cultures, which are bacteria they choose that produce specific flavors, at the beginning of the process. Adding them to the milk while it is still liquid gives the bacteria time to ferment the lactose in the milk.

Historically, cheesemakers used raw milk, and the bacteria in the raw milk soured the cheese. Now, cheesemakers use pasteurization, a mild heat treatment that destroys any pathogens present in the raw milk. But using this treatment means the cheesemakers need to add back in some bacteria called starters – these “start” the fermentation process.

Pasteurization provides a more controlled process for the cheesemaker, as they can select specific bacteria to add, rather than whatever is present in the raw milk.
Essentially, these bacteria eat (ferment) the sugar – the lactose – and in doing so produce lactic acid, as well as other desirable flavor compounds in the cheese like diacetyl, which smells like hot buttered popcorn.

In some types of cheese, these cultures stay active in the cheese long after it leaves the cheese vat. Many cheesemakers age their cheeses for weeks, months or even years to give the fermentation process more time to develop the desired flavors. Aged cheeses include Parmesan, aged cheddars and Gouda.

In essence, cheesemaking is a milk concentration process. Cheesemakers want their final product to have the milk proteins, fat and nutrients, without as much of the water. For example, the main milk protein that is captured in the cheesemaking process is casein. Milk might contain about 2.5% casein content, but a finished cheese like cheddar may contain about 25% casein (protein). So cheese contains lots of nutrients including protein, calcium and fat.

Infinite possibilities with cheese

There are hundreds of different varieties of cow's milk cheese made across the globe, and they all start with milk. All of these different varieties are produced by adjusting the cheesemaking process.

For some cheeses, like Limburger, the cheesemaker rubs a smear – a solution containing various types of bacteria – on the cheese's surface during the aging process. For others, like Camembert, the cheesemaker places the cheese in an environment (e.g., a cave) that encourages mold growth.

Others like bandaged cheddar are wrapped with bandages or covered with ash. Adding a bandage or ash onto the cheese's surface helps protect it from excessive mold growth, and it reduces the amount of moisture lost to evaporation. This creates a harder cheese with stronger flavors.

Over the past 60 years, cheesemakers have figured out how to select the right bacterial cultures to make cheese with specific flavors and textures. The possibilities are endless, and there's no limit to the cheesemaker's imagination.

John A. Lucey, Professor of Food Science, University of Wisconsin-Madison

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Jessica D. Ayers, Boise State University

As a species, humans like to think that we are fully in control of our decisions and behavior. But just below the surface, forces beyond our conscious control influence how we think and behave: our genes.

Since the 1950s, scientists have been studying the influences genes have on human health. This has led medical professionals, researchers and policymakers to advocate for the use of precision medicine to personalize diagnosis and treatment of diseases, leading to quicker improvements to patient well-being.

But the influence of genes on psychology has been overlooked.

My research addresses how genes influence human psychology and behavior. Here are some specific ways psychologists can use genetic conflict theory to better understand human behavior – and potentially advance the treatment of psychological issues.

What do genes have to do with it?

Genetic conflict theory proposes that though our genes blend together to make us who we are, they retain markers indicating whether they came from mom or dad. These markers cause the genes to either cooperate or fight with one another as we grow and develop. Research in genetic conflict primarily focuses on pregnancy, since this is one of the few times in human development when the influence of different sets of genes can be clearly observed in one individual.

Typically, maternal and paternal genes have different ideal strategies for growth and development. While genes from mom and dad ultimately find ways to cooperate with one another that result in normal growth and development, these genes benefit by nudging fetal development to be slightly more in line with what's optimal for the parent they come from. Genes from mom try to keep mom healthy and with enough resources left for another pregnancy, while genes from dad benefit from the fetus taking all of mom's resources for itself.

When genes are not able to compromise, however, this can result in undesirable outcomes such as physical and mental deficits for the baby or even miscarriage.

While genetic conflict is a normal occurrence, its influence has largely been overlooked in psychology. One reason is because researchers assume that genetic cooperation is necessary for the health and well-being of the individual. Another reason is because most human traits are controlled by many genes. For example, height is determined by a combination of 10,000 genetic variants, and skin color is determined by more than 150 genes.

The complex nature of psychology and behavior makes it hard to pinpoint the unique influence of a single gene, let alone which parent it came from. Take, for example, depression. Not only is the likelihood of developing depression influenced by 200 different genes, it is also affected by environmental inputs such as childhood maltreatment and stressful life events. Researchers have also studied similar complex interactions for stress- and anxiety-related disorders.

Prader-Willi and Angelman syndromes

When researchers study genetic conflict, they have typically focused on its link to disease, unintentionally documenting the influence of genetic conflict on psychology.

Specifically, researchers have studied how extreme instances of genetic conflict – such as when the influence of one set of parental genes is fully expressed while the other set is completely silenced – are associated with changes in behavior by studying people who have Prader-Willi syndrome and Angelman syndrome.

Prader-Willi and Angelman syndromes are rare genetic disorders affecting about 1 in 10,000 to 30,000 and 1 in 12,000 to 20,000 people around the world, respectfully. There is currently no long-term treatment available for either condition.

These syndromes develop in patients missing one copy of a gene on chromosome 15 that is needed for balanced growth and development. Someone who inherits only the version of the gene from their dad will develop Angelman syndrome, while someone who has only the version of the gene from their mom will develop Prader-Willi syndrome.

Physical hallmarks of Angelman syndrome include major developmental delays, intellectual disabilities, trouble moving, trouble eating and excessive smiling. Physical hallmarks of Prader-Willi syndrome include diminished muscle tone, feeding difficulties, hormone deficiencies, short stature and extreme overeating in childhood.

These syndromes represent one of the few instances where the influence of a single missing gene can be clearly observed. While both Angelman and Prader-Willi syndromes are associated with language, cognitive, eating and sleeping issues, they are also associated with clear differences in psychology and behavior.

For example, children with Angelman syndrome smile, laugh and generally want to engage in social interactions. These behaviors are associated with an increased ability to gain resources and investment from those around them.

Children with Prader-Willi syndrome, on the other hand, experience tantrums, anxiety and have difficulties in social situations. These behaviors are associated with increased hardships on mothers early in the individual's life, potentially delaying when their mother will have another child. This would therefore increase the child's access to resources such as food and parental attention.

Genetic conflict in psychology and behavior

Angelman syndrome and Prader-Willi syndrome highlight the importance of investigating genetic conflict's influence on psychology and behavior. Researchers have documented differences in temperament, sociability, mental health and attachment in these disorders.

The differences in the psychological processes between these syndromes are similar to the proposed effects of genetic conflict. Genetic conflict influences attachment by determining the responsiveness and sensitivity of the parent-child relationship through differences in behavior and resource needs. This relationship begins forming while the child is still in utero and helps calibrate how reactive they will be to different social situations. While this calibration of responses starts at a purely biological level in the womb, it results in unique patterns of social beahaviors that influence everything from how we handle stress to our personalities.

Since most scientists don't consider the influence of genetic conflict on human behavior, much of this research is still theoretical. Researchers have had to find similarities across disciplines to see how the biological process of genetic conflict influences psychological processes. Research on Angelman and Prader-Willi syndromes is only one example of how integrating a genetic conflict framework into psychological research can provide researchers an avenue to study how our biology makes us uniquely human.

Jessica D. Ayers, Assistant Professor of Psychological Science, Boise State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.