Recent research has shown that we use scent to assess compatibility in finding a partner. Claus Wedekind, a biologist at the University of Lausanne in Switzerland, conducted a study where he gave 44 men T-shirts to wear for two nights in a row. The men refrained from using any scent-based products, so that only their natural scent stayed with the T-shirts (they used scent-free soap and aftershave during this period). Then 49 women sniffed the shirts, and more often than chance, women preferred the shirts of men who were immunologically dissimilar. These women also reported that the scents of their favorite T-shirts reminded them of past and current boyfriends, suggesting that they are consistently choosing partners with the same immunological profile.