Buffalo and Uvalde massacres signal disturbing new trend in mass shootings: NYT
People embrace at a vigil outside of Tops Friendly Market in Buffalo, New York a day after a mass shooting left 10 people dead, in what authorities described as a racially motivated attack

Age has emerged as a key factor in mass shootings, and two recent massacres underscore a disturbing new trend.

Six of the deadliest mass shootings in the U.S. since 2018 were initiated by killers who were 21 years old or younger, which signals a shift from pre-2000 killings that were mostly carried out by men in their mid-20s, 30s and 40s, reported the New York Times.

“We see two clusters when it comes to mass shooters, people in their 40s who commit workplace type shootings, and a very big cluster of young people — 18, 19, 20, 21 — who seem to get caught up in the social contagion of killing,” said Jillian Peterson, a criminal justice professor who helped found the Violence Project.

The accused killers in Buffalo, New York, and Uvalde, Texas, legally purchased semiautomatic rifles shortly after turning 18 years old and proudly posted images of themselves and their weapons online before using them to gun down more than two dozen people combined at a grocery store and elementary school, but recent mass shootings in Boulder, Colorado, El Paso, Texas, Santa Fe, Texas, and Parkland, Florida, also fit this pattern of gunman 21 or younger.

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“These are young guys who feel like losers, and they have an overwhelming drive to show everybody they are not on the bottom,” said Frank T. McAndrew, a Knox College psychology professor who studies mass shootings. “In the case of the Buffalo shooter, it was about trying to impress this community of racists he had cultivated online. In the case of the kid in Uvalde, it was about going back to the place where you felt disrespected and acting out violently.”

Since Columbine, Peterson said, mass shooters have copied and communicated with like-minded individuals, and the Buffalo gunman, in particular, emulated the anti-Muslim terrorist who murdered 51 worshipers in New Zealand, while the Uvalde gunman shared menacing posts on the Yubo platform.

“It’s a way for kids to flex,” said Titania Jordan, of Bark Technologies, a company that monitors platforms for violent content. “It’s a way for them to show strength if they are bullied, or left out. It’s just a part of the narrative now in all these cases — there’s always a social media component.”

Adolescent boys and young men are also going through a critical time in brain development that's characterized by aggressive and impulsive behavio due to what scientists describe as a "huge mismatch" between the parts of the brain that trigger impulsive behavior and other parts that regulate actions -- and the biggest gap occurs in the late teens or early 20s.

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“Then the regulatory systems start to catch up to the impulses, and you’ve got this gradual improvement in ability to control thoughts, emotions and behaviors ongoing into the early 20s,” said Laurence Steinberg, a professor of psychology and neuroscience at Temple University.

That mismatch occurs in the disorienting passage from childhood to adulthood, and young men are "almost universally" in transition in their relationships and living situations, experts say, and many young men are giving "substantial autonomy" by the adults in their lives without much support.

“[There are] major differences in socialization for males and females related to aggressive behavior, appropriate ways to seek support, how to display emotions and acceptability of firearm use,” said Sara Johnson, a professor of pediatrics at the Johns Hopkins University School of Medicine.

That's why many experts on adolescent development advocate for banning the sale of firearms to those under 21, saying that studies have shown the presence of a firearm tends to trigger aggressive behavior.

“There’s an incredible sense of aching despair plus hopelessness, and then there’s a sense of a lack of meaningful connections,” said Jill H. Rathus, a therapist in Great Neck, New York. “Then there’s access to lethal means, that’s the center.”