While we domesticated a variety of animals, dogs, horses, oxen, cows, etc. we reduced our reliance on our own faculties that were replaced by the domesticated animal. In effect the dialectical relationship was not so much one of dominance, as we are now finding out, but of wait for it....mutual aid.
As we planted and transplanted wild grains and developed more domesticated strains, we also settled down into a more domesticate routine, we could no longer be nomadic hunter gatherers.
And as a result our ability to free ourselves from essentially survival tasks allowed us to develop culture, regardless of the reduction in our brain capacity.
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.
BBC - Origin of Dogs Traced
Dogs today come in all shapes and sizes, but scientists believe they evolved from just a handful of wolves tamed by humans living in or near China less than 15,000 years ago.
Three research teams have attempted to solve some long-standing puzzles in the evolution and social history of dogs.
Their findings, reported in the journal Science, point to the existence of probably three founding females - the so-called "Eves" of the dog world.
They conclude that intensive breeding by humans over the last 500 years - not different genetic origins - is responsible for the dramatic differences in appearance among modern dogs
Peter Savolainen, of the Royal Institute of Technology, Stockholm, led the study of Old World dogs, analysing DNA samples taken from dogs in Asia, Europe, Africa and arctic America.
'Bit of a surprise'
His team found that, though most dogs shared a common gene pool, genetic diversity was highest in East Asia, suggesting that dogs have been domesticated there the longest.
Researcher Brian Hare said the dogs outperformed even the chimpanzees, and the puppies were as good as the older dogs, proving the skill was innate and not learned.
"During domestication there was some kind of change in their cognitive ability that allowed them to figure out what other individuals wanted using social cues. The biggest surprise was the puppies - even as young as nine weeks old, they're better than an adult chimpanzee at finding food."
He said the research might ultimately provide some clues as to how social skills evolved in humans.
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