What no one realizes is that the Giver has decided that the present regimented, controlled and emotionless society they live in is worse than the freedom, joy and yes, pain, experienced by people in the distant past. In imparting knowledge of these things to Jonas, he also encourages him to experience them himself, getting him to stop taking his daily injection and sharing information not only of the past, but of the present which of which Jonas was unaware. In the scene pictured above, Jonas learns what their society's term "release" actually means. One of the many things which is strictly controlled in this society is population: once people reach a certain age, they are "released", as are people who flaunt the rules of the elders, or are otherwise undesirable. Most people- and Jonas- believe that this means they go to live outside the community. In actuality, "release" is a euphemism for lethal injection. The Giver shows Jonas what happens at the Nurturing Center where his father works. Nurturing centers are where babies are kept until assigned a name and a family when they're a year old- sex has of course been eliminated as a means of reproduction. Babies are produced by artificial insemination using woman selected to be birth mothers. This allows for- among other things- control over how many babies are produced. There are, however, occasionally complications- such as the birth of a set of twins, which leaves the center one over their allowed quota of babies. The twins are both cared for and carefully monitored and both are healthy, so the choice comes down to weight: the one who is a few ounces heavier is kept. As a horrified Jonas looks on, his father unhesitatingly administers a lethal injection to the other baby then casually puts the body in a box and sends it to garbage disposal.
As it turns out, this perfect, non-violent society hasn't eliminated killing and murder: they've just sanitized and bureaucratized it, and called it by another name. Those involved rationalize it by pointing out that the existence of these people is not beneficial to the community as a whole. In the case of the murdered babies, they clear their consciences of any guilt by denying that the infants are people until they reach a certain age and are assigned a name- and personhood. The parallels between this and abortion are clear: in our own "moral" society, it is legal to kill babies simply because their existence is inconvenient and undesired, or because they are less than physically perfect. Those who perpetrate or champion this great evil justify it by- all science dismissed- denying that unborn babies are human beings. There is no excuse.