Every dog has its day , and scientists are trying to figure out when that first day happened . At some point in ancient history humans developed close relationships with four-legged creatures that would have otherwise been wild , fierce wolves . A new study in the journal Science argues that the domestication of dogs happened between 18,800 and 32,100 years ago in Europe . They say European hunter-gatherer cultures were responsible for turning lupine foes into best friends , long before humans developed agriculture . It 's a conclusion that barks up a controversial tree . The study goes against the idea wolves were domesticated when they wandered over to human agricultural settlements , lured by food . The study also contradicts previous research suggesting that dog domestication may have first happened in the Middle East or East Asia . `` There were many aspects in this study that we did n't expect , '' said Olaf Thalmann , researcher at Finland 's University of Turku , who led the study . Chief among the surprises : the European origin of dog domestication . Digging up bones . Seeking to sniff out when and where domesticated dogs emerged , scientists turned to genetics . Researchers extracted and sequenced mitochondrial DNA . Mitochondria are structures in cells that convert food energy into usable forms . When working with these ancient samples , scientists focused on mitochondrial DNA because it is more prevalent in cells than DNA within a cell 's nucleus . Scientists recovered DNA fragments from the genomes of 18 prehistoric dog and wolf-like carnivores and 20 modern wolves with origins in Eurasia and America . Researchers compared these mitochondrial genome sequences with those of 49 wolves , 77 modern dogs , 3 Chinese indigenous dogs and 4 coyotes . By highlighting similarities in DNA sequences among all of these specimens , researchers put together trees of close relationships called `` clades . '' The more similar two creatures ' sequences are , the closer together they will be in the clade . Researchers organized the specimens in the study into four clades , with three of these groups having sister species represented by ancient fossils from Europe , and the fourth relating to modern wolves as well . It appears , based on these groupings , that the oldest domesticated dogs were in Europe . The carcasses that ancient hunters left behind may have attracted wolves , which could have led to a relationship between dogs and humans , study authors said . A group called Clade A includes examples of the modern dog breeds Basenji and Dingo , as well as some pre-Colombian New World dogs as old as 8,500 years . The ancient dogs of the Americas seem to have already been domesticated when they got there , having arrived with humans , Thalmann said . `` What we propose is actually the process that led to dog domestication in Europe also gave rise ... ( to ) dogs in the New World . '' Clade A demographically shows a connection with humans . Between 5,000 and 2,500 years ago dog population declined , but then began to rise sharply starting about 2,500 years ago , said Thalmann . Human population size also went up at that time , indicating that dogs were dependent demographically on the human societies , he said . Meanwhile , wolves became more scarce , as agrarian cultures emerged and wolves lost their habitats and wild game . Surprisingly , researchers did not find a population of modern wolves that might have given rise to modern dogs . In fact , modern dogs have more genetically in common with ancient wolves than the ones we see today . `` It 's quite likely that the population of wolves that gave rise to modern dogs does not exist anymore , '' Thalmann said . Dogs vs. wolves . Another big surprise from the study is , based on mitochondrial DNA , the two most ancient samples of dog-like creatures included in this study did n't seem to be dogs at all . One of the oldest samples was previously described in a 2011 study in the journal PLOS One , led by Nikolai Ovodov , a co-author on the new Science study . Ovodov and colleagues described remains of a `` dog-like '' creature from Razboinichya Cave in Siberia , about 33,000 years old , and found similarities between it and domesticated dogs from Greenland that lived about 1,000 years ago . But the new study 's genetic analysis suggests that this particular sample is an ancient sister lineage to modern dogs and wolves , not a direct ancestor . A 36,000-year-old dog-like carnivore found in Belgium does not seem to represent a direct ancestor either . `` We did not expect that these two particular dogs -- the putative earliest dogs -- that they 're not directly related to modern dogs , '' That 's not something the study authors expected , Thalmann said . So what 's going on ? There are two theories about what happened to these creatures , Thalmann said . It 's possible that both of these fossils represent early attempts of humans to domesticate dog-like animals . These creatures did not appear to leave any descendents , so they may signify a failure of domestication . Alternatively , these creatures may not have been domesticated at all , but rather unusual wolves that died out before the last Ice Age . More recent specimens -- such as a 14,700-year-old fossil from the Oberkassel site in Bonn , Germany , and the 12,500-year-old fossil from Germany 's Karstein cave -- seem to be more directly related to modern dogs . Scientists previously had evidence based on their physical features , but the new mitochondrial genome analysis adds more support , Thalmann said . By 14,000 years ago , `` dogs had become a consistent component of human settlements and were subject to deliberate burial themselves and were included in human graves , '' the PLOS One study said . On the scent of other theories . This new study does n't present the whole story , however . It did not include ancient samples from the Middle East or China , which are alternative proposals for the origins of dog domestication . Thalmann anticipates that this will be a criticism of the study . Also , regarding wolves , the study included fewer wolf samples from the Middle East and East Asia than other areas , potentially skewing that part of the analysis as well . But , notes the study 's senior author Robert Wayne , a biologist at the University of California , Los Angeles , the oldest dog fossils from East Asia are no more than 8,000 years old , making them much younger than the European samples and dating from well after the domestication of dogs . The oldest Middle Eastern dog remains are between 10,000 and 12,000 years old , and so still more recent than the European fossils . Mitochondrial DNA from ancient canines from these areas would make for a more complete picture of canine evolution , but it was not available in this study . If a 20,000-year-old dog fossil were available from these areas , scientists would also need to find other fossils to arrange them in a tree of relationships , Thalmann said . If those were genetically more closely related to modern dogs than the European samples , that would argue for a different origin of domestication -- but such samples have not been recovered . This result seems unlikely , given the close associations found between modern dogs and ancient European wolves and dogs , Wayne said . Many questions remain about the first domesticated canines . They may be dog-gone , but science is making sure they 're not forgotten . Follow Elizabeth Landau on Twitter at @ lizlandau .
Study : Dogs were domesticated between 18,800 and 32,100 years ago . European hunter-gatherer cultures domesticated dogs , researchers say . This contradicts other previously held theories .