To understand whether humans are at the limit and therefore killing children by averaging too many babies we need to answer a few questions.
First, do we humans have the ability to average enough babies such that our number could have reached our current 7+ billion numbers before today, given how long humans have existed? There is no doubt that we have sufficient fertility and more than enough time. Today there are at least 40 million people proving that we can average more than 6 children. The countries of Niger, Mali, Burundi, and Somalia all are averaging more than 6 children and their total population is above 40 million (The World Factbook). To get a feel for what this means, let's assume a horrible child mortality rate where 1/3 of all children die. That means an average of 4 children are reaching adulthood and reproducing. This will double the population every generation or roughly every 25-30 years. At this rate 2 humans will become a population of 4 billion in 32 generations or about 800 to 1000 years. It is estimated that humans have existed with our current DNA for about 200,000 years. Clearly humans have enough fertility and much more than enough time to have reached a higher population number than the current 7+ billion. Therefore, either we humans are at the limit or we humans have some way to limit our fertility such that we do not reach the limit. Notice too that human population numbers rarely increased at an exponential growth rate, which supports the concept that we have hit the limit.
Second, do we clever humans limit our births to avoid the calamitous situation where we reach that 60th minute? To answer that let's first refer back to Suzuki and Bartlett. They both make the point that the bacteria will not recognize the problem before it is too late. At the 59th minute the beaker is half full. One generation later, it is full. In order to ensure the environment does not fill, we would have to recognize the impending disaster and devise ways to reduce the number of children the group is averaging to a level that will keep the population from reaching the limit.
There are many different social rules that humans have created to limit the number of babies we create, for example, marriage and the taboo of getting pregnant out of wedlock. In addition there are physical mechanisms that limit the fertility of women when times are stressful. These have fooled many scientists into believing that we do control our overall average number of children and therefore stop our population growth before hitting the limit. Unfortunately none of these can bring the fertility low enough to prevent the population from growing. An extreme example will illustrate this.
Most people understand that they should not create a baby if they cannot afford to provide for that child. Let's take that to the extreme where nobody has a child that they will be unable to keep alive until adulthood. If that algorithm is performed flawlessly, then no child will be killed as a consequence of averaging too many babies. However, notice that if the other people average say 3 children, then 1/3 of all those children will grow up to be so poor that they know in advance that they will not be able to keep their babies alive. The notion that somehow we can know in advance and not create the baby, if in the next 12-20 years we will be unable to provide for that person, is of course absurd. There are plenty of child starvation deaths every year providing proof that we fail to implement this algorithm. In addition, notice that at best this produces poverty so severe that the people suffering it know that they will never be able to afford a child.
There are physical mechanisms that shutdown or limit fertility to prevent pregnancy in stressful situations, but again, the subset of individuals that are suffering this stress cannot prevent those that are not suffering from averaging too many babies, and creating that stress.
When the population is at the limit, averaging too many babies creates child mortality. However nobody really knows this, so the notion that somehow we limit the number of babies we average in response to suffering the consequences, as an argument that we are not at the limit, makes no sense. We humans never put the cause of death as "too many people, because we averaged too many babies". For example someone posted "John, you claim the problem is all overbreeding??? Most infant deaths are caused by DIRTY WATER!" on the Suzuki youtube.com article in response to my comments. Notice how this comment is attempting to use a proximate cause of death, death by dirty water, to state that these deaths were not caused by averaging too many babies. All causes of death satisfy nature's refusal to feed too many individuals, but notice the stunningly poor choice of an example cause of death. There is no lack of clean water on this planet, except when 7+ billion humans all need it. The only thing stopping people from access to clean water, is other people.
Finally, the theory of evolution depends upon excessive breeding. It is wishful thinking to expect humans to be different from all other species in this regard.