To: primate-talk@primate.wisc.edu
Subject: [PT] Domesticated Primates?



(from suddarth@aztec.asu.edu [ DEVON SUDDARTH ])

Theory suggets greater role for man's best friend


By Shelly Simonds


Dogs and humans have been best friends for a long time - about 100,000
years - according to the latest estimates. But one ANU anthropologist
could create a new controversy with his latest hypothesis about the
human-dog relationship.


According to Dr Colin Groves, Reader in the Department of Archaeology and
Anthropology in the Faculty of Arts, not only did we domesticate dogs,
but dogs may have domesticated us.


Dr Groves believes early humans came to rely on dogs' keen ability to
hear, smell and see - allowing certain areas of the human brain to shrink
in size relative to other areas.


"Dogs acted as humans' alarm systems, trackers and hunting aids, garbage
disposal facilities, hot-water bottles and children's guardians and
playmates. Humans provided dogs with food and security. This symbiotic
relationship was stable over 100,000 years and intensified in the
Holocene [Period] into mutual domestication," said Dr Groves. "Humans
domesticated dogs and dogs domesticated humans."


In a keynote address to the Australasian Society for Human Biology in
December, Dr Groves repeated an assertion made by others as early as 1914
- that humans have some of the same physical characteristics as
domesticated animals, the most notable being decreased brain size.


The horse experienced a 16 per cent reduction in brain size after
domestication while pigs' brains shrank by as much as 34 per cent. The
estimated brain-size reduction in domesticated dogs varies from 30 per
cent to 10 per cent.


Only in the last decade have archaeologists uncovered enough fossil
evidence to establish that cranial capacity in Homo sapiens declined in
Europe and Africa by at least 10 per cent beginning in the Holocene
Period, about 10,000 years ago.


Dr Groves believes this reduction may have taken place as the
relationship between humans and dogs intensified and the animals allowed
for the diminishing of certain human brain functions like smell and
hearing.


Brain size is not uniformly reduced with domestication, said Dr Groves.
The forebrain and the corpus callosum shrink the most while the midbrain
and the medulla are least affected; in humans, however, the midbrain and
the olfactory bulbs are strongly reduced.


Dogs are by far the oldest domesticated species, showing up on the
archaeological record about 10,000 years ago. Until recently this was
widely accepted as the date for the domestication of dogs.


However, a ground-breaking paper by a group of international geneticists
last year pushed this date back by a factor of 10.


Led by Robert Wayne, at the University of California Los Angeles, the
team showed that all dog breeds had only one forbear, the wolf, by
analysing the mitochondrial DNA of 162 wolves from around the world and
140 domestic dogs representing 67 breeds.


"The study found that dogs have been separate from wolves for as long as
different geographic groups of wolves have been separate from each other
- and that is a very long time indeed," said Dr Groves.


The present day gene pool of dogs is varied and well-mixed, according to
the study. A review of the research in Science magazine noted that only
one other mammal exhibits the rare combination of vast genetic diversity
and widespread well-mixed gene pool - humans.


A coincidence? Dr Groves doesn't think so.