Fleas could be in a symbiotic relationship with a rat. This would be known as parasitism because the flea is drinking the blood from the rat when the rat is losing blood to survive. (: <span />
It is estimated that the agriculture was invented 10000 to 12000 year ago. At this period of time, the modern humans or the <em>Homo sapiens</em> were spread to America.
The <em>Homo sapiens</em> begin to form villages and started domesticating animals. Also, all other ancestors of humans were possibly dead up to this period. The agriculture developments and advancements occurred after 10000 year ago.
Hence, the correct answer is <em>Homo sapiens. </em>
Bovine veterinarians i believe