> The changing climate killed more, but the humans were the differentiating factor, so which one do you point the finger at?

If we're the differentiating factor, I'd have to blame us. Am I right in understanding that these species were normally being thinned during each glacial maxima, such that it was already a set part of their evolutionary environment? If that's right, then aren't we the ones to blame?

Otherwise, is a murderer merely a "contributing cause" to someone's death if the victim happens to be sick at the time of the killing?