According to The Modern Farmer, people have been farming deer since the 1970s. The link provided also explains the benefits deer farming has over conventional livestock farming. The one fundamental problem I have with this is that they're still farming wild deer. Which means that they are not yet completely reliant on humans, along with other environmentalist complaints.
So let's hypothesize on deer farming during the Neolithic, a time when agriculture was just starting. We still have Rangifer, the caribou, only this time, they are FULLY domesticated, not SEMI-domesticated. There are also the deer listed in the link, too:
- Cervus (wapiti, sika and red deer, though I'm personally not so sure considering how big and volatile they are, especially during rutting season)
- Axis axis (chital, or Indian spotted deer)
- Dama dama (fallow deer)
- Odocoileus (whitetails and mules)
If any one of these have been bred to serve humans in the sixth or seventh millennium BCE, would we still breed cattle, sheep and goats along with them, or would the domesticated deer fill all three niches at once?