2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/44335Observational manifestations of possible breaking of spin-statistics relation for neutrinos are considered. It is argued that bosonic neutrinos may form cosmological cold dark matter, improve agreement of BBN predictions with observations, make operative Z-burst model of ultra-high energy cosmic rays, etc. Restrictions for an admixture of bosonic component to neutrino which follow from double beta decay are discussed.17 pages, 2 figures; talks at Neutrino Telescopes, Venice, 22/02-25/02, 2005 and Rencontre LaThuile-05, 27/02-05/03, 2005High Energy Physics - Phenomenologytext