subject: evolution

Take It Easy: Neonatal Milk Hormones Influence Infant Social and Cognitive Behavior

Take It Easy: Neonatal Milk Hormones Influence Infant Social and Cognitive Behavior

Email, texts, IM, Facebook, Instagram—in the age of social media, there is no shortage of ways to send a message from one person to another. But is mother’s milk the original social network? Many of milk’s ingredients are believed to act as signaling factors that convey a “message” from mother to infant. Over the last decade, researchers have worked on decoding these messages, with a particular focus on the hormone cortisol. Milk cortisol levels are associated with infant growth and infant temperament in rhesus macaques, and hypothesized to send the message to be more cautious and prioritize growth over behavioral activity. A newly published study expands on this hypothesis and tests whether milk cortisol levels during the first weeks of life predict behavior and cognitive performance months later. The results suggest that far from being an instant messenger, milk’s signal may have effects well after it is received. Read More...

Tasmanian Devil Milk Provides Powerful Antibacterial Proteins

Tasmanian Devil Milk Provides Powerful Antibacterial Proteins

The Tasmanian devil is best known for being a swirling, growling, trouble-making cartoon character. But the marsupial mammal's reputation is about to get a complete makeover, thanks to new research on the function of proteins secreted in their milk and their skin. Read More...

Getting the Balance Right

Getting the Balance Right

Once described as an epidemic, obesity has now reached pandemic status with an estimated 600 million obese adults worldwide, and an additional 1.4 billion that are overweight. The cause of the pandemic is known—people consuming more energy (calories) than they expend—so it would seem that the solution would be to simply eat less. But a team of nutritional ecologists believes that cutting calories will not solve anything, because it ignores some basic tenets of human (and animal) biology. Using data from fruit flies, mice, birds, fish, monkeys, and humans, Raubenheimer, Simpson and their colleagues demonstrate a seemingly universal law of animal nutrition: a predominant appetite for protein. They propose that the human need to meet a fixed daily protein target leads to weight gain through the overconsumption of low protein foods that have come to dominate the Western diet. Rather than advocating for a high protein diet that eschews carbohydrates, they emphasize a balance of macronutrients for optimal health. Can dairy help strike this balance? Whole-food sources of protein that are easy to access, like dairy, can help balance out those beloved low-protein, high-carbohydrate processed foods and keep energy consumption in check. Read More...

Ancient Aurochs Genome Contains the DNA Blueprint for Modern Cattle

Ancient Aurochs Genome Contains the DNA Blueprint for Modern Cattle

A preserved specimen of aurochs bone was discovered deep beneath the Derbyshire Dales in the UK in the 1990s. Aurochs are an ancient cattle breed domesticated around 10,000 years ago somewhere around modern day Iran. In Europe, the last of these animals were still found on a Polish royal reserve as recently as the 17th century. Park et al., have now extracted enough DNA from the ancient bone specimen to sequence the aurochs genome. When they compared the aurochs sequence to the DNA of cattle breeds we know and use in domestic agriculture today, they found a surprisingly high level in common with British and Irish cattle. Read More...

Accounting for Lactase Mutants

Accounting for Lactase Mutants

Back in the 50s and 60s, work on lactose intolerance was often published under cringeworthy and blunt racial titles. A Nature article from 1969 sums it up with ‘Can Asians Digest Milk?’ It was also probably a subliminal non-accident that ‘lactose intolerance’—which is the typical condition for adult humans—became common parlance for a trait for which those with northern European ancestry are the real mutants. Many decades on, the genetic basis of the ability to digest lactose has been largely pinned down. As it turns out, there are different genetic reasons for the mutants’ lactose tolerance in the various populations that drink milk without intestinal incident, and the gene that confers mutant power in Europeans is only part of the story. That research history is discussed below, along with recent work that has extended the field’s reach beyond genetics. Investigations of the transcontinental basis of lactose tolerance are now providing insights into mankind’s cultural, as well as biological evolution. Read More...

Milk Protein Comparison Unveils Nutritional Gems for Human Infants

Milk Protein Comparison Unveils Nutritional Gems for Human Infants

As any new parent can tell you, human newborns are very needy—and for good reason. Born at an earlier developmental stage than their primate relatives, human infants must accomplish a great deal of fetal development (some say the equivalent of nine more months!) outside of the womb. Responsibility for this “fourth trimester” falls squarely on the shoulders of human breast milk, and so it is no surprise that decades of research have searched for attributes in human milk that support the unique developmental needs of human infants. While much of the focus has gone to milk fats and carbohydrates, a new study has turned the attention to milk proteins (1). Utilizing new methods in protein identification, Beck et al. present the most comprehensive human milk proteome (the list of the types and quantities of all proteins in milk) to date, as well as the first milk proteome for a nonhuman primate, the rhesus macaque. Despite having less total protein than rhesus macaque milk, Beck et al. found that human milk has more than three times the types of proteins in rhesus milk and higher quantities of nearly every milk protein that the two species share. Their findings demonstrate that from digestion, to immunity, to neurodevelopment, human infants get more of a boost from milk proteins than their primate cousins. Read More...

A Time Before Nipples

A Time Before Nipples

What was milk like long ago in evolutionary history? In the absence of a time machine, the next best way to answer this question is to take what is known about the diversity of living mammals and work backwards using deductive logic, just like Sherlock Holmes. Recently, progress in this area has received a major boost from two papers about the different sugars found in monotreme milk—monotremes being the wackiest and most ancestral-like of the mammal groups, with membership so exclusive it is limited to only two kinds, the platypus and the echidna. Read More...