Let's see: the average human life span is now almost 80 years, from around 30 years through most of history and pre-history. Women no longer have a high risk of dying during childbirth. People no longer have to have a dozen children in the hopes of seeing at least one survive until adulthood. I wouldn't be alive today without the advances in human knowledge that have given us modern medicine, and I thank God for giving us people willing to devote their entire lives to advancing knowledge.
BTW, the term "survival of the fittest" simply means surviving to reproduce. Fit organisms reproduce; unfit organisms do not.
According to Moses people during the first 2000 + years after the formation of The Adam lived nearly a thousand years. Imagine that if you can, Methuselah lived 969 years, the longest recorded life span in a flesh body. It was the Creator repulsed by the activities of His children that brought forth the flood. Only Noah and his family of the descendants of the Adam, had not mixed with the fallen angels.
I know that for the all ethnic peoples we find upon this earth today that one of two things had to have occurred. Noah took two of every flesh, including all ethnicities, or else that flood only covered the portion of this earth wherein the descendants of the Adam that had polluted their bloodline to Christ. Now there is some evolutionary biology to study.
It was just prior to the flood that God shortened the flesh life span to 120 years.
I do not dispute that 'modern medicine' has in many cases extended the life span of many people. But eventually all flesh dies and returns to the dust from which it came....and their soul/spirit, good - bad- or indifferent returns to the Maker that sent it to be judged.
Oh and that term "survival of the fittest' has become so politicized it means whatever the entity handing out dollars or demanding dollars, decides it means. Our founders stated that there are unalienable rights that come only from the Creator, 'life, liberty, and the pursuit of happiness... whereas liberals claim they can do things better, playing 'god' decide who they will fund to survive.