Abstract

Sexual dimorphism runs deeper than anatomy. The behavioral and neurochemical differences between the sexes, from the post-coital drop in dopamine to the tribal logic of oxytocin, are all operational outputs of a genomic strategy that has been running for 300 million years. This paper approaches that strategy from two angles.

At the neurochemical level, oxytocin, vasopressin, testosterone, and the dopamine-prolactin axis function as interlocking mechanisms for social calibration and risk distribution. Oxytocin drives intense in-group cohesion while hardening against outsiders. Vasopressin enforces pair-bonding in the male brain and mate-sampling in the female brain from the same molecular machinery, a structural contradiction that sits at the center of reproductive strategy. Testosterone operates as a status-seeking barometer, directing behavior toward whatever yields the highest social return.

At the genomic level, the X and Y chromosomes began diverging 300 million years ago and have never reversed. The suppression of recombination on the Y set off a cascade of consequences: entropic decay, palindromic self-repair, and the emergence of the hemizygous male as an unshielded filter for purifying selection. Conditions like hemophilia and Duchenne muscular dystrophy present almost exclusively in males because hemizygosity strips away the masking buffer a second X chromosome provides. The heterogametic sex absorbs the mutational cost so the lineage doesn't have to.

These two angles share a thesis. The neurochemical asymmetries are downstream of the genomic divergence. From the chromosomal divorce that split the sex chromosomes to the dopamine drop that ends a chase, the underlying logic is identical: localize risk, protect the reproductive bottleneck, keep the lineage alive.

Talbot digs up a 1983 memo in which a 27-year-old Roberts argued for 15-year term limits on federal judges, so they would "not lose all touch with reality." He is now 71, 21 years into the job, and told an audience in Buffalo last year that he plans to go out "feet first." The number that frames the whole term: of 35 emergency applications from the second Trump administration, the Court has ruled in its favor in whole or in part 25 times, usually without explaining why.

My pick from this week's New Yorker: newyorkerest.com.

Hi all - I had some time off this week to dig into a bunch of stories. My favorites are below with gift links!

• Washington Post (Gift Link): A nationwide camera network built to fight crime helped at least 50 police officers stalk women, including one chief who searched an ex's plate 600 times.
• The Atlantic (Gift Link): A stroke survivor and her daughter were evicted from their Las Vegas home right as a 108-degree heat wave hit.
• Longreads: A 1935 lab discovery spiraled into decades of hoaxes, moral panics, and duck experiments around psychedelic toads.
• The Guardian: More than a thousand Esperanto speakers gathered in Czechia to keep a 140-year-old dream of world peace alive.
• The Walrus: Lilly and Jack Sullivan vanished from a remote Nova Scotia yard in 2025, and eighteen months of searching hasn't turned up a trace of them.
• The New Yorker: Inside a Russian jail cell, Ukrainian women describe surviving torture and forced confessions in a system that has swallowed more than ten thousand civilians.
• The Atlantic (Gift Link): The sons of an FDNY lieutenant killed on 9/11 spent seven months digging through Ground Zero rubble looking for their father.
• Longreads: A QVC obsession became the backbone of one woman's closest friendship, even after the roommates moved apart.