Useful News for You

Call this a dog-bites-almost-everyone story.

President Biden’s dog Commander is in the doghouse this week after new reports detailed 10 incidents in which the German shepherd bit Secret Service agents (including one that required a hospital visit) or exhibited “aggressive behavior” between October 2022 and January 2023.

Erin Hecht says it might not entirely be Commander’s fault. Hecht, an assistant professor in Harvard’s Department of Human Evolutionary Biology, spearheads “The Canine Brains Project” to help us to better understand why dogs are the way they are. She said he might just be triggered by a number of stressors at the White House (by all accounts, a pretty stressful place).

“Dogs are individuals, like people. And like people, they have different reasons for responding aggressively or fearfully in different circumstances,” said Hecht, whose research focuses in part on neural and behavioral variation in domestic canine breeds. She added that, “prior traumatic experiences can influence their behavior later in life.”

Commander arrived at the White House in 2021 after the Bidens sent another German shepherd, Major, who was a rescue and also had problems with biting and aggression, to live in a quieter environment with family friends.

Hecht said most dogs bite out of fear, not anger, and that dogs are hardwired to avoid biting their humans.

“As a species, their brains are wired to trust us and partner with us,” she said. But, like people, fear can give them a short fuse, and push them to act out.

“Other dogs,” she added, “behave aggressively out of a need to defend a resource, like food, a toy, or a favorite person. Understanding an individual dog’s profile is important for management and treatment.”

Hecht said in addition to knowing what triggers a dog may have, most dogs also show physical warning signs before biting. To prevent incidents, she said, dog owners should learn the signs to keep themselves and others safe.

“Most dogs will communicate that they feel threatened before they bite through body language like freezing, turning away, and lip-licking.”

For those dealing with stubborn behavioral issues, such as the Bidens, Hecht said the owner should have their dog evaluated by a professional to rule out underlying medical issues, identify situational and motivational triggers, and work out a management plan.

“Depending on the dog, that plan might include medical treatment, training strategies, adjusting the dog’s environment, adjusting the behavior of the people in the environment, or choosing to move the dog to a different environment,” she said. “A veterinarian is a good first step and can refer you to other resources and professionals.”

In the case of Commander, Hecht said it’s a good example of dog reactivity and aggression, exemplifying how much we still don’t know.

“This news story is a high-profile reminder of an issue that affects the lives of many dogs and humans in this country every day,” she said. “Despite this, science still doesn’t know very much about the biology of canine aggression.”

Canine Brains Project looks to learn more about our furry friends through data gathered by a combination of an online surveys, genetic samples, and canine MRI scans. The study looks at dogs with and without traumatic early life experiences, and with and without current fear and aggression issues. Volunteers interested in submitting their own dog’s information can learn more here.

Wondering is a series of random questions answered by experts. For this entry, we asked Sharon Bober, an associate professor of psychiatry at Harvard Medical School and the director of the Sexual Health Program in the Department of Psychosocial Oncology and Palliative Care at Dana-Farber, whether partners in an intimate relationship can be close without sex.

Intimate relationships are similar in some ways, but different in others. Some intimate relationships are more sexual and powered by a lot of physical chemistry at the beginning and stay that way. In other intimate relationships, partners feel very connected to each other, but neither is strongly focused on physical intimacy. It really depends on what works for each couple.

In relationships that are intimate but not sexual, if both partners feel that they’re getting their needs met, and they feel close and mutually supported, then it works. It’s perfectly healthy. It’s also normal when some of the intensity or spontaneity that people experience in a brand new relationship settles into a dynamic that is more familiar or predictable. You don’t need to have sex in order to feel close.

The issues around lack of sex in relationships really come when partners are not in alignment. The main goal, especially in intimate relationships, is that partners are able to communicate with each other around what it is that they want and need. The first thing to remember when it comes to communication is that it’s really important for people to speak about their own experience rather than accusing or focusing on what the other person should be doing. It’s helpful to use “I” statements. Start out by saying, “I’d like to find some time for the two of us to talk about the relationship” or “I’ve been having some feelings that I’d like to share with you.”

Sexual chemistry is very real: We all intuitively have a sense about that, but chemistry can change depending on the context. For example, when you’re dating it might feel very different than when you’re living together. It might look even more different when you’re working, you have young kids, and it’s tough to find time just to sleep and exercise. It’s not a coincidence that couples feel more chemistry when they are on vacation or having an adventure that’s fun or exciting.

When it comes to maintaining sexual chemistry, desire and sensuality are things that we have to cultivate and to attend to over time. That might mean paying more attention to your own needs. That might also mean taking a little bit of extra time to figure out what your partner is wanting or needing. Relationships, whether they’re sexual or not sexual, need to be cared for and renewed regularly. They are not automatically self-sustaining. You have to actually pause, pay attention, and care for them.

— As told to Clea Simon/Harvard Correspondent

How does the human brain navigate complex circumstances — say, driving through Harvard Square traffic at 5 p.m.?

One theory gaining support with psychologists and neuroscientists is that the brain creates causal models of the world that help with planning and execution. It’s akin to running mental simulations to see which outcomes are good or bad. “You learn this internal model of the environment, which you can use to predict what will happen if you take different courses of action,” explained Momchil Tomov, an associate in psychology Professor Samuel Gershman’s Computational Cognitive Neuroscience Lab.

In recent decades, computer scientists have developed these ideas into a system dubbed Reinforcement Learning (or RL for short). Researchers such as Tomov who work at the intersection of psychology and technology have even introduced computational models that attempt to capture how RL plays out in the brain. In a new paper published in Neuron, Tomov and his co-authors used functional magnetic resonance (fMRI) to compare their algorithmic theory against real-world imaging.

Why craft algorithms that attempt to formalize human thinking and decision-making? “It’s difficult to study cognitive processes without having a precise computational model that maps inputs to outputs,” said Tomov, who earned his Ph.D. in neurobiology at Harvard in 2019 and worked with Gershman as a postdoc until 2021.

Researchers also hope their work leads to advances in RL, which can navigate complex environments and is considered one of the biggest success stories in artificial intelligence. It has, in fact, bested humans in realms including board and video games, but until recently has proven a somewhat slow learner. “Algorithms that are more human-like can perform better in certain domains than traditional machine-learning,” Tomov said.

The group’s experiment leans on the prior work of two of the study co-authors. Thomas Pouncy, another doctoral researcher in Gershman’s lab, outlined in 2021 a more complex, theory-based RL system. A computational theory-based RL model was introduced in a subsequent paper by MIT postdoctoral researcher Pedro Tsividis. It proved much faster than previous iterations in learning new video games. In terms of speed, Tomov said, it’s far closer to the human ability to pick up on such a task.

The whole process led the researchers to hypothesize on the neural architecture of human decision-making and learning. In the new study, the researchers tested their algorithm on 32 volunteers who played and eventually mastered Atari-style video games while hooked up to fMRI scanners, which measure the small changes in blood flow that come with brain activity.

As the researchers expected, this yielded evidence of activity theory-based models in the prefrontal cortex at the front of the brain with theory updates occurring in the posterior cortex, or back of the brain. Where their hypotheses — and their algorithm — diverged was in the details. The researchers specifically expected to find evidence of theory-based models in the orbitofrontal cortex. Instead they found them in the inferior frontal gyrus. This makes sense in hindsight, Tomov said, as previous research out of Gershman’s lab found the inferior frontal gyrus involved with learning “causal rules that govern the world.”

More surprises were found at the back of the brain, where the occipital cortex and the ventral pathway — both central to visual processing — appear to be involved when those models require updating. “Whenever you get surprising information that is inconsistent with your current theory, that’s when we see not just an update signal in the ventral pathway, but also, that’s when the theory becomes activated in the inferior frontal gyrus,” Tomov summarized.

Finally, fMRI scans revealed the directional flow of information in the brain. Tomov and his co-authors had hypothesized that information flows bottom-up. Instead, it seems to flow top-down during game play.

“It’s almost as if it’s coming from the model, stored somewhere in the prefrontal cortex, flowing down to the posterior visual regions,” he said. “But then when there’s a discrepancy — when an update happens — the pattern of information flow flips. Now information flows bottom-up, from posterior regions to frontal regions.”

Tomov has been studying theory-based RL with Gershman for four years. Two years ago, he started applying these ideas to self-driving cars as a full-time employee with a Boston venture. “How do you get from here to the next intersection and make a left turn without hitting anyone?” he asked. “Basically, there’s this internal model of the world with other drivers and predictions about what they’re going to do.”

Mars as we know it is a cold, dry planet, incapable of hosting life. But scientists believe this wasn’t always the case, and a recent study suggests that the period during which the Red Planet may have had liquid water on its surface — and the chance of life — was longer than previously believed.

A more detailed examination of a previously studied martian meteorite reveals the possible underpinnings of such a compelling prospect. Researchers in the paleomagnetics lab of Professor Roger Fu, John L. Loeb Associate Professor of the Natural Sciences, have uncovered evidence that Mars had a global magnetic field, much like Earth’s, for hundreds of millions of years longer than was once believed. Such a field can deflect harmful cosmic rays, enabling the possibility of an atmosphere, with all that implies.

“On Earth, our magnetic field seems to do a good job of shielding our atmosphere from space radiation and solar wind,” said Sarah Steele, a third-year graduate student in Earth and planetary sciences and first author of “Paleomagnetic evidence for a long-lived, potentially reversing martian dynamo at ~3.9 Ga,” published in May in Science Advances. “We think that’s part of what keeps the Earth surface habitable.”

While it is still unknown if this happened on Mars, the new timeline increases the possibility. The research team looked for records of the planet’s magnetic field, which would represent evidence of an early martian dynamo. The dynamo, she explained, describes the way liquid in the planet’s core moves to make strong magnetic fields around the planet. “If the dynamo was longer-lived on Mars and if it played the same role, that may have helped keep the surface habitable longer. But on the other hand, the magnetic fields around Mars could have functioned really differently — maybe they even helped the atmosphere escape to space.”

Previous evidence had suggested that Mars had lost its dynamo — and its accompanying strong, planet-encompassing magnetic fields — 4.1 billion years ago, Steele said. However, with the use of an innovative new quantum magnetic field microscope, the researchers were able to place the loss at 3.9 billion years ago or later. “Those sound very close together,” she said, of the dates. “But a giant chunk of the stuff we are interested in, such as the questions about water, is in that window.”

Karma Nanglu says his favorite animal is whichever one he’s working on. But his latest subject may hold first-place status for a while: a 500-million-year-old fossil from the tunicates, a wonderfully weird group of marine invertebrates.

“This animal is as exciting a discovery as some of the stuff I found when hanging off a cliffside of a mountain. … It’s just as cool,” said Nanglu, a postdoctoral researcher in the Department of Organismic and Evolutionary Biology.

In a new study in Nature Communications, Nanglu and co-authors describe the new fossil, named Megasiphon thylakos, revealing that ancestral tunicates lived as stationary, filter-feeding adults and likely underwent metamorphosis from a tadpole-like larva.

Tunicates are truly strange creatures that come in all shape and sizes and have a wide variety of lifestyles. An adult tunicate’s basic shape is typically barrel-like, with two siphons projecting from its body. One of the siphons draws in water with food particles through suction, allowing the animal to feed using an internal basket-like filter device. The other siphon expels the water.

There are two main tunicate lineages, ascidiaceans (often called “sea squirts”) and appendicularians. Most ascidiaceans begin their lives looking like a tadpole and morph into the barrel-shaped adults. They live their adult lives attached to the seafloor. In contrast, appendicularians retain the look of a tadpole as they grow to adulthood and swim freely in the upper waters.

“This idea that they begin as tadpole-looking larva that, when ready to develop, basically headbutts a rock, sticks to it, and begins to metamorphose by reabsorbing its own tail to transform into this being with two siphons is just awe-inspiring,” said Nanglu.

Interestingly, tunicates are the closest relatives of vertebrates, which include fish, mammals, and even humans. How this odd-looking creature could be related to vertebrates would be hard to imagine were it not for that tadpole beginning. Tunicates’ close relationship to vertebrates makes studying them critical for understanding our own evolutionary origins. Unfortunately, it’s not easy to do, as tunicates are almost completely absent from the entire fossil record, with only a handful appearing convincingly as members of the group.

With so few fossils, scientists relied mainly on what could be learned from modern tunicate species. Because no one knew the morphology or ecology of the last common ancestor of the tunicates, scientists could only hypothesize that it was either a two-siphoned, benthic animal living at the sea floor, like the ascidiaceans, or a free-swimming animal like the appendicularians.

M. thylakos had all the hallmarks of an ascidiacean tunicate, the barrel-shaped body and prominent siphon-like growths. But the feature that stood out to the team was the dark bands running up and down the fossil’s body.

High-powered images taken of M. thylakos allowed the researchers to conduct a side-by-side comparison to a modern ascidiacean. The researchers used dissected sections of the modern tunicate Ciona to identify the nature of Megasiphon’s dark bands. The comparisons revealed remarkable similarities between Ciona’s muscles, which allow the tunicate to open and close its siphons, and the dark bands observed in the 500-million-year-old fossil.

“Megasiphon’s morphology suggests to us that the ancestral lifestyle of tunicates involved a non-moving adult that filter-fed with its large siphons,“ said Nanglu. “It’s so rare to find not just a tunicate fossil, but one that provides a unique and unparalleled view into the early evolutionary origins of this enigmatic group.”

M. thylakos is the only definitive tunicate fossil with soft tissue preservation that has been discovered to date. It is the oldest of its kind originating from the middle Cambrian Marjum Formation in Utah. The fossil was recognized as a tunicate by co-authors the Department of Organismic and Evolutionary Biology’s Rudy Lerosey-Aubril a research associate, and Assistant Professor  Javier Ortega-Hernández while they were visiting the Utah Museum of Natural History in 2019.

“The fossil immediately caught our attention,” said Ortega-Hernández. “Although we mostly work on Cambrian arthropods, such as trilobites and their soft-bodied relatives, the close morphological similarity of Megasiphon with modern tunicates was simply too striking to overlook, and we immediately knew that the fossil would have an interesting story to tell.”