I've been wondering for a while what would need to be done to produce post-humans - a race of folk who are fixed and do not suffer the physiological problems that evolution has bestowed upon us. In my ignorance I thought it would not take much. No. That is wrong. I now see there are loads of flaws in the human body.
One of the biggest has to be the pharynx - the design of which means the larynx and oesophagus are very close. So we cannot eat while we breathe, nor breathe while we eat. How many deaths must that contribute to every year? About 4,000 in the US alone. But that's just one, almost everywhere you look in the body there are bugs. These range from the macro (spine) to the micro level (genes).
- The spine - started out as a suspension bridge but now we walk upright it's acting as a pillar. I'm no engineer but that does not seem like a good choice.
- Wisdom teeth
- The tibia - about 50% of stress fractures are of this bone
- The menstrual cycle
- The recurrent laryngeal nerve - good for fish. For humans? Not so much.
- The human body's response to certain sorts of heart failure makes people sicker. A lot of the medicine given to people who have suffered systolic heart failure is to combat these deleterious effects.
- John C Avise has written extensively on the basic, built-in problems that can cause diseases. He notes that about 75% of human genes are documented to carry mutational defects associated with one disease or another. Here is the full list.
- Humans cannot synthesise their own Vitamin C - unlike almost every other animal. The reason? The gene for the enzyme to do this is defective in humans (and many other animals).
The big problem with any attempt to bio-engineer a better body (leaving aside the knotty ethical problems aka eugenics) is our complexity. We are starting to know more about what genes build a baby (Hox) but we are a long way from doing anything other than tinkering. Is this why transhumanists emphasise fixes via other means such as better prosthetics?
I wonder what else would change if we were fixed? If those bugs in our biology could be swept away. We'd be healthier and live longer. But a lot of living emerges from our biology. The tides of hormonal change and bodily reactions to what we do or is done to us are the well-springs of our behaviour. Our biology rules, or ruins, our choice of mate. If my happiness with someone is not related to the make-up of their immune system what would I respond to? Alternatively, would everyone be attracted to someone who has an incredibly strong immune system?
My reaction to what you said is determined by the stew of chemicals my brain is steeping in at any point in time. Though there are obviously limits to the range of reactions given my biology. So the fixed would be different. They might seem genuinely strange but also have their own quirks.