Dr. Becker of Mercola.com suggests that ‘lack of fear in humans started as a cell abnormality’.
According to Adam Wilkins of Berlin’s Humboldt University: “When humans bred these animals for tameness, they may have inadvertently selected those with mild neural crest deficits, resulting in smaller or slow-maturing adrenal glands. So, these animals were less fearful.”
Domestication causes genetic changes (even in fish!). Here is Dr. Becker’s list:
(white patches, brown regions)
|Smaller ears||Shorter muzzles|
|Smaller teeth||Docile behavior|
|Smaller brain or cranial capacity||More frequent estrous cycles|
|Juvenile behavior||Curly tails|
Becker says that floppy ears are actually the result of deformed ear cartilage and these animals presumably don’t hear as well as those with erect ears. Also, domesticated animals have a smaller size of forebrain than their wild counterparts.
Taking dogs’ ears alone, could dogs with erect ears generally be more ‘wild’ – alert and reactive – than dogs with floppy ears? Hmmm.
Going back to Adam Wilkins’ hypothesis about the size of adrenal glands, has anyone thought of comparing the average size or maturity of the adrenal glands in Border Collies and German Shepherds with erect ears as opposed to, say, Golden Retrievers and Labradors or compared the relative size of their forebrains?
I have found utrasonographic adrenal gland measurements in dogs (without evidence of adrenal disease) which was interesting but unfortunately doesn’t mention breed. The Wiley Online Library relates measurements to the size of the dog, but again not to the breed (and particularly not to ears!): ‘Findings support our hypothesis that adrenal gland size correlates with body weight in normal dogs’.
I just wonder whether there can be any correlation at all between erect ears in dogs, adrenal function and fear – the main purpose of the adrenals being to enable the body to deal with stress from every possible source.
If lack of fear indeed started as a cell abnormality, were those Silver Foxes of Belyaev that successfully morphed into tame and totally different looking animals in only about 40 generations, those already with ‘mild neural crest deficits, resulting in smaller or slow-maturing adrenal glands‘ or did these deficits develop? Chicken or egg?
Possibly I should steer clear of scientific things I know nothing about!