Why a lower life expectancy and a higher birth rate is better

Thanks to modern medicine, life expectancy has increased substantially. More children survive childhood, and people live longer. But perhaps it's too good to be true? What if the status quo of higher life expectancy and lower birth rate requires a large expenditure of energy that's ultimately based on petroleum that may not be available in the future?

Childbirth

When more children survive childhood through external factors like caesarean birth, there is less "evolutionary pressure" to be able to survive natural childbirth.

An analogy: suppose some birds somehow get isolated on an island where there are no predators. Eventually, some of them will lose the ability to fly, beause on this island there is no evolutionary pressure to be able to fly. There are no predators to eat the birds that don't fly. Soon the flightless birds will multiply. But this isn't necessarily to say that the flightless birds are somehow inferior. Because nature tends to be economical, it will often (within an ecological niche) get rid of unnecessary features because those features are expensive to maintain. Within an ecological niche such as the ground, a flightless bird is more efficient than a flying bird. So on this island, the ability of flight has been trimmed from some of the birds because it is unnecessary and wasteful. Still there will be flying birds as well, because they occupy a different ecological niche (the air). In the air, obviously the flightless birds don't do well at all but the flying birds do quite well.

In human populations, lack of evolutionary pressure leads to similar outcomes. When childbirth becomes safer through external factors (caesarians, etc), there is less evolutionary pressure for babies to present properly or grow to a safe size within the mother, and there is also less evolutionary pressure for mothers to be able to give birth naturally. Over time, this lack of evolutionary pressure leads to small but significant increase in the average size of babies, and small but significant decreases in the size of the female pelvis. Eventually, a situation may result wherein women cannot give birth naturally any longer and require medical assistance. Whereas now childbirth is a normal function of the human body, eventually it will become a medical emergency.

There are at least two problems that I can see with this situation:

1. It requires the presence of a medical industry that is often parasitic. Parasitic because it is more profitable for those in the medical profession to recommend that women get c-sections even if they are capable of giving birth naturally. Eventually when women lose the ability to surive a normal childbirth, it is the medical profession that will profit the most.
2. If for some reason medical care on a large scale isn't available, then it's possible that unimaginable numbers of women and children will die in childbirth. Returning to the example of the birds on the island, suppose predators such as dogs are introduced to the island. The flightless birds will most likely be wiped out. Similarly, when the childbirth environment changes (lack of medical care), the large proportion of women with pelvises too small or who are giving birth to too-large babies will not survive childbirth.

Just as in the breast-cancer industry that profits from donations to fight breast cancer, the medical industry similarly plays on our emotions when it comes to the safety of women and children in childbirth.

Childhood

Another factor that increases life expectancy is that more children these days survive into adulthood, thanks to antibiotics, vaccines, better hygiene, safety practices, etc. Same as in childbirth,  children who survive to adulthood with the help of external factors no longer face evolutionary pressure to survive to adulthood unassisted. This will lead to weaker immune systems on average, antibiotic overuse and resistance, reliance on vaccines, allergies becoming more common, etc. Soon children will come to rely on external factors to keep them alive because there is no pressure to be self-reliant. Again, the medical industry profits from this state of affairs.

Old age

Still another factor that increases life expectancy is that people live longer. Again, people rely on various (and usually expensive) medical interventions to help them survive to an old age. In fact, the cost of keeping a person alive for a year increases as that person ages. This is because as they get older they require more expensive interventions to keep them alive. It is not unreasonable to suggest that it costs more for one person to live to 100 than for two people to live to 50 each. Again, the big winner here is the medical industry. In order to justify the spending required, they play on our emotions, just as they do when it comes to women and children.

There are several disadvantages to having a large elderly population, apart from the required amount of medical intervention. The elderly are also less productive and a lot of welfare spending goes to them. And of course someone has to pick up the bill for this, and that is the taxpayer.

Higher birth rate

Thus far we've considered the factors that raise life-expectancy. If we were to overhaul this system, it would result in a lower life expectancy. But if more people are dying, then there will need to be some way to sustain population levels. Thus a higher birth rate is justified. However, it has to be done the right way. It makes little sense to encourage single mothers to have lots of children, because those children will ultimately wind up costing society far more than having a higher life expectancy. I believe that, done the right way, a higher birth rate will make people happier. People will be more productive (because younger people are more productive on average), and people will be more health conscious. It is well known that the more you take care of someone, the less care they take of themselves. It shifts the responsibility of survival to the individual, where it belongs.

With a lower life expectancy and a higher birth rate, government could go back to the ideal of "defending and protecting the right of an individual to life, liberty, and property", as explained by Frederic Bastiat. Such a setup requires less taxes, less government interference, less welfare, less medicine, less energy expenditure, more robust children and therefore people, etc. People will also have children earlier, which also leads to positive outcomes for children (better genes and parenting).