My husband brought my attention to a recent article on msnbc which reports on a fossil find in Eritrea suggesting that humans have eaten beef as far back in time as 2.5 million years ago.
The fossilized remains feature a longhorned skull that looks strikingly like the totem animal of a certain Texas collegiate football team. The skull was painstakingly reassembled from shards that were found in the same dig with the remains of early humans. It belonged to a species called Bos, which is described as "essentially a missing link between more modern cow-like species found in Eurasia and the earlier African cattle ancestors found alongside hominids and dating back 2.5 million years."
The article doesn't go into a lot of detail about the evidence, but the basic thrust is that humans were associating with cattle that long ago. It's particularly interesting in light of this earlier article discussing archaeological evidence that humans began grinding grains much earlier than was realized. Such finds could revolutionize the entire history of food.