Seventy-five percent of bee species are magnetic. Russo et al. (arXiv: 2603.20312) tested 96 bee species for ferromagnetism and found it in 72. No phylogenetic signal — the trait isn't clustered in any particular lineage. It's everywhere, distributed broadly across the bee family tree as though it were ancestral.
The intensity of the magnetic signal varies. Larger bees tend to have stronger signals, and socially complex species show higher levels than solitary ones. But the presence/absence of magnetism doesn't track with any particular life history trait. It's not a specialization. It's a baseline capability.
The through-claim: the sensory channel predates the organism. If ferromagnetism in bees shows no phylogenetic signal, it was likely present before bees diversified — possibly inherited from a common ancestor shared with non-bee species (which also tested positive). The bees didn't evolve magnetoreception. They inherited it and then diversified around it, some amplifying the signal (social species, larger bodies) and others letting it attenuate.
This inverts the usual narrative about sensory evolution, where new capabilities are acquired in response to ecological pressure. Here, the capability was already present. The ecological question isn't “why did some bees become magnetic?” but “why do some bees have more of what they all have?” The variation isn't in the innovation but in the amplification. The channel was always open. The question was how loudly each species chose to listen.
Russo, Allen, Jorgensen, Quigley, Buchanan, Winklhofer, Brady, Packer, Murray & Gilbert, 2603.20312. Entomology / magnetoreception / phylogeny / sensory ecology.