New York: Scientists have mapped the DNA of 27 ancient dogs spanning back 11,000 years and found that there were at least five different types of dogs present at the end of the last Ice Age.

For the study, published in the journal Science, the research team studied dog DNA dating as far back as 11,000 years ago, immediately following the last Ice Age.

By sequencing the DNA of 27 dogs found in Europe, the Near East and Siberia, team members discovered five different types of dogs with distinct genetic ancestries dating from before any other animal had been domesticated.

They extracted DNA from skeletal material to see how dogs evolved from thousands of years ago when all humans were still hunters and gatherers. "The dog samples have been gathered from museums, and other collections from across the world and by several members of this team," said study author Anna Linderholm from Texas A&M University in the US.

"Since we don't know when and where dogs were domesticated, we have collected most of the known dogs from the old world, going back as far in time as possible and using dog DNA that has been best preserved," Linderholm added.

The samples were taken from collected dog remains, such as a tooth or a piece of bone. From the samples, the DNA was sequenced, enabling the team to read the genetic code that explains the origins of each dog and how it might have been related to modern-day dogs.

"By looking at a dog's genome, we can look at that dog's history, look at his parents and their parents and so on," she said. She added that dogs look similar genetically, meaning they share a more recent common ancestor.

"The five lineages from over 11,000 years ago is more diversity than we have been able to identify before," Linderholm said. According to the researchers, all dogs seem to have originated from one ancient wolf population -- a wolf population that has since disappeared.

"We have no connection with our modern-day wolf populations with our first domesticated dogs," the study authors wrote. The researchers said that the human-dog bond can now be seen a bit more clearly. When humans moved, they almost always took their dogs with them. "We note a clear link between the movement of people and the introduction of a new type of dogs," they wrote.