People protest the separation of children of immigrants from their families outside Metropolitan Detention Center, where U.S. Immigration and Customs Enforcement detainees are held in Los Angeles. (Mario Tama/Getty Images)

James A. Coan is a psychology professor at the University of Virginia and host of the science podcast “Circle of Willis.”

The federal government is considering opening tent facilities on military bases to house the swelling numbers of young people detained at the U.S. border with Mexico, including hundreds of children forcibly separated from parents accused of illegal entry. Since the White House instituted its policy of taking children away from parents, Chief of Staff John F. Kelly assured the public that “the children will be taken care of — put into foster care or whatever.” Even if that were true — facts remain scarce about the quality of care in the sprawling detention program, and the prospect of tent cities is unsettling — the children may already have been harmed by the separations alone.

As a clinical psychologist and neuroscientist at the University of Virginia, I study how the brain transforms social connection into better mental and physical health. My research suggests that maintaining close ties to trusted loved ones is a vital buffer against the external stressors we all face. But not being an expert on how this affects children, I recently invited five internationally recognized developmental scientists to chat with me about the matter on a science podcast I host. As we discussed the border policy’s effect on the children ensnared by it, even I was surprised to learn just how damaging it is likely to be.

At minimum, forced separation will cause these children extreme emotional distress. Most of us know this intuitively. Less intuitive, as Nim Tottenham of Columbia University told me, is that “the sadness is not the thing that really matters here. What matters is this is a trauma to the developing nervous system.” Extreme emotional responses to separation from parents is part of evolution’s plan to keep those parents close — to “break any parent’s heart,” as Megan Gunnar of the University of Minnesota said. That’s because throughout human evolution, an absent caregiver has meant almost certain death. Jude Cassidy of the University of Maryland put it best: When faced with separation from loved ones, “we fight as if it’s a matter of life and death, because it is.”

But little minds and hearts can maintain that level of distress only for so long before the children face a horrifying decision: Continue, through severe emotional pain, to call out for their parents, or proceed on the assumption that their parents are gone. As Dylan Gee of Yale University explained, for those who choose the latter path, their brains will start down a course of “accelerated development” — they’ll mature more quickly. The problem is that rapid maturation often comes at the cost of cognitive and emotional inflexibility later on, as well as the assumption that the world is extremely dangerous and threats must be avoided automatically, without thinking. According to Gunnar, this assumption of perpetual danger will cause some to suffer from chronic, low-level inflammation, as if they are constantly battling a mild infection. Charles Nelson, a pediatrics professor at Harvard Medical School, provided the comprehensive long-term view: As those children grow and develop into adults, the combination of chronic inflammation and behavioral inflexibility will impair their health in at least two ways — through direct weathering of their bodies and less effective problem-solving, impulse control and decision-making.

Just to make sure I’d heard him right, I said: “So psychological trauma is mediating a pathway to brain trauma, and that is affecting behavior down the road, which can affect health and longevity?” He replied: “Yeah, you got it.”

I have a strong intuition that if Americans were seeing migrant children being obviously mistreated physically by U.S. border agents they would not abide this situation for an instant, whatever the dubious legal rationale. Such abuse would be recognized for what it obviously was: violence against children. Just because the damage being done today at the border with Mexico is not visible shouldn’t make it any less disturbing. Those in Congress who have been slow to rein in this insidious White House policy should be aware, as they ponder how to proceed, that these children wrenched from their parents will long bear the scars of the lawmakers’ inaction.