In Guns, Germs, and Steel, which animals most helped Eurasians in Chapter 9?

Jared Diamond lists fourteen different animals which he
argues most helped Eurasians. He groups them together as the "Ancient Fourteen."
Interestingly, all but one apparently originated in Eurasia; yet all had distant
relatives (similar animals) in other countries who were not so easily domesticated. He
also draws an important distinction between "domesticated" animals and "tame" animals
Domesticated animals have lived with and in relationship with humans for so long that
they have evolved by nature to function well in captivity. "Tame" animals are not so
hardwired. Diamond says animals which could be domesticated had to be gentle and passive
enough not to be a danger to the humans who came to depend on them. He also comments
that the animals normally were gregarious "pack" animals who were accustomed to
following a stronger leader. This, he argues, allowed humans to step into the role of
the leader which the animals would follow. This is certainly true of horses, pigs,
goats, cattle and sheep. Dogs and other animals were domesticated by humans, but did not
provide the enormous benefits that were provided by the Ancient
Fourteen.

Aside from furnishing meat, the Ancient Fourteen
were work animals who could pull a cart or plow, give milk, etc. This made them
immensely important to the Aryan peoples of Eurasia.