Amazing statistic courtesy of Daniel C. Dennett in his book Breaking the spell: religion as a natural phenomenon (as found at 3 Quarks Daily).
Since both the domesticated animals and their domesticators have enjoyed huge population explosions (going from less than 1 percent of the terrestrial vertebrate biomass ten thousand years ago to over 98 percent today--see Appendix B) there can be no doubt that this symbiosis was mutualistic--fitness-enhancing to both parties.This is amazing. I had commented before on The Living Planet Index that it should also include humans and our livestock. I had no idea that this would account for 98% of terrestrial vertebrates.
I came across this in his TED Talk (if you haven't checked out the TED talks you should, some really interesting speakers there). He attributes this calculation to Paul MacCready. I tried to figure out exactly how Paul calculated this and was unable. But I did find out that the original figure was .1% (rather than 1%) and that this includes all land and air vertebrates (excludes marine vertebrates).
According to Eco-Economy there are 1.5 billion cattle and buffalo and 1.8 billion sheep and goats that humans have domesticated. Add in 6 billion humans and that is a lot of biomass.