The following is an interview with Xiaoming Wang, author of Dogs: Their Fossil Relatives and Evolutionary History. Wang is a curator of vertebrate paleontology at the Natural History Museum of Los Angeles County and has been studying the evolutionary history of the family Canidae for the past 20 years.
Q: Why study the fossil history of dogs?
Xiaoming Wang: The fossil records of the canids (dogs) present a unique opportunity to study this important family of predators. The richness and diversity of the fossil canids are unparalleled among modern families of Carnivora (mammalian predators). Such fantastic records, assembled over more than 100 years of careful collecting by vertebrate paleontologists, permit us to piece together a detailed evolutionary history of the family and enable us to ask many questions that cannot be easily answered by studying other groups of carnivorans.
Q: Why are the fossil records for canids so rich and abundant?
XW: Canids were among the first carnivorans to evolve, dating back to more than 40 million years ago. This long history gave canids an early head start in diversifying before other carnivoran groups had an opportunity to compete. In addition, there are rich fossil records for canids because they evolved adaptations to a more cursorial locomotion (capable of running fast and for long distances), which is ideal for living in open grassland. The global climate became cooler and drier during the late Cenozoic, conditions that favor grassland over trees. Canids thrive in such an environment and the great number of fossils of members of this family testifies to their success.
Q: What makes the dog family unique?
XW: Social hunting is one of the trade-marks of modern wolves. Having the ability to form a complex social group and the capacity to pursue prey in a highly organized manner are characteristics of the dog family (only the hyena family shares these traits with the canids among the carnivorans). Evolutionarily, canids are flexible (adaptable) predators that were often quick to take advantage of opportunities that resulted from the occasional extinction of other carnivorans.
Q: How do dogs differ from cats? What are their similarities?
XW: There are numerous anatomical distinctions between cats (felids) and dogs. Canids, for example, have a relatively long snout, blunt claws, a full complement of cheek teeth (four premolars and two or three molars), and a single-chambered bulla (bony chamber that houses the delicate ear bones). In contrast, felids have a shortened snout, sharp claws, reduced cheek teeth (two premolars and one molars), and a two-chambered bulla. Both dogs and cats are superb predators that rely on capturing preys as their means of daily subsistence.
Q: Evolutionarily, what is the path that dogs took in their approach to predation?
XW: Canids—particularly large ones, such as wolves, tend to be pursuit predators. They hunt in packs, collaborating to be efficient in catching preys as well as maximizing their killing power.
Q: Is social hunting unique to the canids?
XW: No. Hyenas also hunt collaboratively. Some cats, such as lions, do it as well.
Q: Why are canids uniquely suited for domestication? Why were canids the first animals to be domesticated by humans?
XW: It is likely that ancestral domestic dogs, a subspecies of the gray wolf, were highly social animals. Their ability to interact among themselves may be a key factor in the development of their association with humans when circumstances arose. Dogs are the most social of the historically important domestic animals (horse, cow, sheep, goat, pig, chicken), which may have led humans to recognize that they could be domesticated.