This just isn't true. Not only is cannibalism somewhat common amongst the animal kingdom, there's nothing to support the idea that animals don't eat species that are similar. Lions, tigers, and chimpanzees all eat other members of their own species on occasion.
However, cannibalism, and to a lesser extent eating similar species, does present problems beyond simply depleting the gene pool. For instance, the chance of contracting a disease from your meal is much higher if its a similar animal (likely to be susceptible to the same pathogens).
I think the point Dr. Rozzi is making is that although we like to think humans are deviant from other species in this way, there is evidence to the contrary.
(BTW, lions don't eat tigers because tigers are 2x as large, and they don't coexist outside zoos. I get your point, but couldn't resist :-)
However, cannibalism, and to a lesser extent eating similar species, does present problems beyond simply depleting the gene pool. For instance, the chance of contracting a disease from your meal is much higher if its a similar animal (likely to be susceptible to the same pathogens).
I think the point Dr. Rozzi is making is that although we like to think humans are deviant from other species in this way, there is evidence to the contrary.
(BTW, lions don't eat tigers because tigers are 2x as large, and they don't coexist outside zoos. I get your point, but couldn't resist :-)