Did you read the article you just link to me?

" A new silverback leader is likely to kill the infants in the group, sothe nursing females will stop lactating and their reproductive cycleswill restart. Murdering the young of other males thus makes it possible for the new silverback to sire children of his own."

So its not Gorillas recognising which children are their's and which are not at an innate level that human beings don't have - otherwise they would be wiping out children at any age. It's about having the urge to mate as soon as possible, something harder to do when a new mother is nursing a child. It's a more simpler thought of "I want to mate, and have not had the opportunity to mate before"- something your own article states, rather than "I must wipe out the alternative bloodline to preserve my own" which is fairly complex.

Thanks for sharing the article, because it reminds me at something I was hinting with when I mentioned smaller mammals before. I've seen a similar thing with rabbits. A male rabbit gets a female rabbit pregnant, the female gives birth, and then the male will try to kill the babies to get the female rabbit ready to mate again.

Now, if I'm following your line of thinking - that behavior would not make sense. The rabbit has created the next generation of rabbits. It's not trying to get rid of a rival rabbit's bloodline - it's his kids he's killing! Unless of course, the rabbit's desires aren't as complex as "I must preserve my bloodline for future generations" - and more "I want to mate"

Gorillas are a big more complex I recognise, hence their reluctance to kill their own offspring if they do not have the urge to mate currently (And Gorillas fertility periods I believe are more restrained than rabbits) - but I wonder why you think rabbits will kill their own offspring almost immediately to start mating again if, as you said earlier, primitive species like rabbits both are aware of who their offspring are and have a basic evolutionary function of ensuing their survival. (Source for information on rabbits)

And while we're up, here's an article detailing the many barriers preventing animals from linking sex to pregnancy

It even gives another explanation for why silverback gorillas are likely to wipe out infants if not because of recognising that sex leads to pregnancy.

One more interesting piece of reading - key details - Mountain gorilla males, who tend to spend more time babysitting and caring for children than most ape species - have little or no interest in whether the children are their's or not, but all males focus on caring for the children.