Cats cosy up for rewards: study

Gods, mousers extraordinaire or cold-blooded killers.

Whatever your view of Felis silvestris catus, there's no denying domestic cats are popular - there are about 600 million worldwide.

The bond with people goes way back. In Cyprus, the remains of a human and a cat were found buried together in a 9500-year-old grave, pre-dating Egyptian cat art by about 4000 years.

Scientists believe the relationship began when people adopted more agricultural lifestyles and saw value in keeping the rodent hunters around.

Unlike other domesticated animals bred for food, herding, hunting or security, most of the 30 to 40 cat breeds originated only in the past 150 years, and selection was mostly for aesthetic rather than functional reasons.

However, scientists investigating changes that occurred during domestication have found domestic cats' genes evolved to help them thrive in the household department.

Wesley Warren, of the Genome Institute in the US, and colleagues sequenced the genome of a female Abyssinian - a domestic breed - and compared it with the genomes of six other domestic breeds, two wild cat species and four other mammals.

They found that compared with their wild counterparts, domestic felines have changes in genes involved in memory, fear conditioning, stimulus-reward learning and alterations that support increased listening and visual alertness.

This could suggest the processes by which cats became domesticated.

The finding were published in Proceedings of the National Academy of Sciences.