Prediction: organisms will recognize (& favor) their own offspring if there"s a risk of misdirecting their parental investment. Invest in kids that offer the best return on investment: whether they will make it or not, important to direct parental investment towards their own children. When lamb is born, mother will lick baby, to change brain understanding to be able to tell this lamb is my lamb: preferentially nurse her lamb. Sheep are mobile, lambs move around a lot, therefore mom needs to differ offspring from others: therefore, special mechanisms to discriminate their lambs from others. Rat defends nest, so that other babies cannot enter the nest: defending nest because location-based, and the babies in the nest are her babies. Never expect an intelligent answer from an animal, including humans, in an environment its not adapted to. General point: some species use individual recognition; others use different cues that are just as effective in species natural environment.