Social organization in Eulipotyphla: evidence for a social shrew
Résumé
Shrews and their close relatives (order Eulipotyphla) are typically considered
to be solitary. This impacts our understanding of mammalian social evolution:
(i) the ancestor of mammals is believed to have been shrew-like, and even
though Eulipotyphla are not more basal than other mammalian orders, this
might have been one reason why the first mammals have been assumed to
be solitary-living; (ii) Eulipotyphla are the third largest mammalian order,
with hundreds of species entering comparative analyses. We review primary
field studies reporting the social organization of Eulipotyphla, doing a literature
research on 445 species. Primary literature was only available for 16 of
the 445 species. We found 56% of the studied species to be social (38% were
living in pairs), which is in sharp contrast to the 0.5 and 8% reported in
other databases. We conclude that the available information indicates that
shrews are more sociable than generally believed. An interesting alternative
hypothesis is that the mammalian ancestor might have been pair-living. To
understand the social evolution of mammals, comparative studies must be
based on reliable and specific information, and more species of all orders
must be studied in the field.