Yah, I got a bit carried away and and referenced something half remembered from a documentary. It’s a bad habit I haven’t succeeded in breaking yet. Sorry.

The paper below states that evidence indicates initial domestication probably occurred in East Asia.
http://adsabs.harvard.edu/abs/2002Sci…298.1610S

My understanding however is that the the current dominant hypothesis is that domestication happened in one area and the resulting animals accompanied humans as we migrated to new locations rather than domestication re-occurring in each new area with other canid species.

In my (inexpert) view this makes them as non-native to most areas of the world as we are.

As for the break down of droppings. That is a weak argument on my part and I don’t have any sources to back it up. My (again, inexpert) understanding is that the waste collectors for a given local ecosystem will specialize in the nutrients and composition of what is left by true native species’ and that they may not be adapted to effectively handle everything left by domestic dogs. My further understanding is that the manufactured diet (canned wet food and bagged dry food) of most owned dogs would compound the issue.

What makes you think that dogs are only native to central Africa? Have you ever heard of wolves, or maybe coyotes? Archeology shows that there were dogs in North America in the Pre-Columbian era (that is before Columbus “discovered” the Americas.)

Not disagreeing that dog poop has plenty of nasty organisms in it, just that they aren’t native outside of Africa, or that the soil isn’t able to break dog poop down.

The biggest reason is disease control. Any feces will contain numerous types of harmful, infectious organisms. Those commonly found in dog’s droppings include various types of worms, salmonella, and giardia. When droppings aren’t picked up and disposed of properly they will increase the spread of these organisms and the diseases they cause in humans, other people’s pets, and wild animal populations.

This can happen by direct exposure to the droppings but also through indirect means. Some organisms will migration into soil and persist after the droppings are no longer present. Others will wash away in rain to contaminate local waters. Others will spread with the help of animals that feed on feces, flies and rats being common examples. This last example is compounded because the extra nutrients help these animals breed more successfully increasing their populations.

It’s also important to remember that unless you are in central Africa dogs are not a native species. This means that, unlike those of native species, dog droppings may not break down efficiently or support the local ecosystem by “fertilizing the soil”. In some cases they may actually damage local systems by supporting the excess growth of various algae or fungi.

Also remember that in areas with a sufficiently dense population of dogs (read many urban environments) the amount of waste left can easily exceed the ability of natural processes to remove it. A lot of poop can pile up very quickly if not disposed of.