Originally Posted by
John Chardine
If we indeed have an example of "cannibalism" here, I wanted to make sure people understood that there is nothing counter-adaptive to this special type of predation. There is a hugely pervasive understanding out there on the street that individual organisms behave "for the good of the species". You see this frequently in the popular press and even on supposedly authoritative wildlife specials on TV. I once saw a reference to this in so many words in the respected magazine "New Scientist" but they refused to admit it.
If we assume for the moment that individuals do indeed behave for the good of the species, then cannibalism is hard to reconcile. However, we know that natural selection works in a different way- behaviours are selected for the good of the individual or gene, not the species, so with this in mind a Peregrine is just a food item to another Peregrine.
The only thing that cannibals have to be careful of is eating relatives. This would be strongly selected against because of the decrease in inclusive fitness that this would entail (a gene for indiscriminate cannibalism would quickly go to extinction because it would essentially destroy itself). So, however abhorrent cannibalism may be, there is nothing bizarre about it from an evolutionary standpoint.