Apes, spite and sympathy

I was dubious about reports of research said to show that 'spite is a uniquely human emotion'. But I haven't really thought my doubts through. It looks as if Neil Fairweather articulates one quite well in a letter to New Scientist:

Chimpanzees are incapable of spite, it seems...but researchers are having difficulty reconciling this with the idea that chimps do exhibit altruism. I suggest a simple explanation: spite is not the "evil twin that cannot be separated" from altruism, as researcher Keith Jensen puts it. Altruism is the tendency to do things that benefit others, at your own expense. Its opposite is miserliness. Spite is the tendency to attempt to harm those who have benefited in your stead. Surely its opposite is the tendency to attempt to help those who have suffered while you have gained. Is this not sympathy? If chimps show sympathy towards individuals who have been deprived for their benefit, but not spite towards those who have benefited from their loss, then there might be some explaining to do.

[For textbook nastyness, see reports of mass "execution" of gorillas in Congo.]