Hopkins Reader

You — and Me

Published in Hopkins Medicine - Fall 2020

Johns Hopkins neuroscientist David J. Linden has a knack for grabbing a reader’s attention.

In the prologue to his fascinating new book about the complicated “biochemical machinery of life” that forms the traits making you who you are — and others who they are — he describes joining the online dating site OkCupid.

Linden ultimately found his soulmate, whom he went on to marry. He also found that browsing dating profiles “was a master class in human individuality.” It left him wondering: What makes us all so different? What makes one person incredibly athletic and another passionate about science? What drives our unique preferences for food, music and other entertainment?

“It turns out that there’s a different explanation for each of these traits,” Linden writes, and how they develop can have “profound implications.”

The author of three other books on the biology of behavior and a longtime professor in the Department of Neuroscience at the Johns Hopkins University School of Medicine, Linden is well-equipped to explore the origins and importance of human individuality. His lab at Johns Hopkins has long worked on the cellular basis for memory storage and recovery of function after brain injury, and he served for many years as chief editor of the Journal of Neurophysiology.

Throughout the eight chapters of his latest work, the neuroscientist compellingly shows that how we become unique is one of the deepest questions we can ask. In a style that’s both authoritative and witty, Linden analyzes vital aspects of what shapes our selfhood, including genetic inheritance (“It Runs in the Family”), gender identities, sexual orientation, and dreams and sleep patterns. He also provides a powerful debunking of the “pseudoscientific” theories that undergird racism.

Among his key points is that genes are built to be modified by experience, and genetic instructions for development are not precise. In other words, our genes do not preordain our destiny.

Perhaps most importantly, he lambastes as hogwash the oft-held view that “nature” or “nurture” must battle it out to determine our individuality. “The idea that nature and nurture must be in opposition to explain human traits is silly,” he writes. “The biological challenge is that the wiring diagram of the human brain is so enormous and complicated that it cannot be specified exactly in the sequence of an individual’s DNA.”

The latest scientific studies of human development, genetics and the plasticity of the nervous system “can be controversial stuff,” he observes.

For example, on the issue of sexual identity, he says, “The argument in favor of sex and gender equality, including intersex people and a spectrum of gender identities, must be a moral argument about the way things should be, not a biological argument about the way things are. If tomorrow there were definitive proof of certain inborn average differences in the brain functions of women or intersex people or trans people, that would not be an argument for maintaining a system that denies them equal opportunity.”

Although Linden admits suffering from “the curse of the geek to overanalyze,” his Unique is an adept, deeply researched, engaging book. It is an intriguing, scientifically serious and always thoughtful guide through the labyrinth of the brain — and the “random nature” of its “self-assembly” of 500 trillion heritable but often mutable genetic and cellular connections — that determines how our individuality is formed within it.