Just having severed nerves able to rejoin would be a big plus.
And while we’re at it, figure out some better way of separating the placenta from the uterus than <RIIIIIIIIIIIPP!>
Make sure that anything you do doesn’t degrade the ability to adapt to a different environment, such as a collapse of civilization. Reducing digestive efficiency to eliminate obesity is just going to kill you faster in a famine or even a temporary food shortage like being lost in the woods for a few days. Better to improve the “full” appetite cut-off feedback system.
Ideally you want things that are:
a) not going to increase the energy and resource drain on the mother during fetal development, so that pregnancy is not going to impair **her **survival chances,
b) be advantageous in all, or the great majority of situations, not just in US urban living or on a snorkelling vacation,
c) isn’t a disadvantage in other significant situations (how do you keep your gills from drying out when you’re not in the water), and
d) doesn’t demand trade-offs such as increased energy/food requirements that would be a disadvantage in other environments (gills would be a huge drain of energy to develop and maintain if we are not going to be actually living in the water for most of the time).
Obviously the solution is just more eyes, of different types, sensitivity, ranges, color receptors, wider field of view, etc. We’d have to see if the brain needed any significant modifications to process the input, though I hypothesize the answer is “not really”.
That’s what other species do. Like jumping spiders: the two big eyes are their “fancy” eyes, while the others are for just movement, etc. Some of the things you mention we might have the infrastructure for, e.g. it has been shown that 2-cone monkeys can be given 3 cone types and make use of it in a useful way.
One idea would be to create an immune system that doesn’t destroy its host while it kills of “invaders”. I refer not just to autoimmunity, but to the very common and potentially very lethal effects of merely fighting off a simple bacterial infection (i.e. eliminate things like SIRS/sepsis and ARDS.
Vonnegut cover this in his novel Slapstick. If I remember correctly,
the Chinese eventually become so small that they basically become viruses, lethal to full-size humans.
I’m quite fond of the respirocyte idea, myself, but this would fall into the category of ‘cyborgisation’ or ‘prosthetics’ rather than genetic engineering. Other possible prosthetic enhancements could be bones made from aggregared carbon nanorods (hyperdiamond)
and artficial muscle fibres stronger than muscle cells.
There might be a role for genetic engineering in all this, however; removing biological organs and replacing them with artificial ones would interfere with a myriad different interconected biological systems, and the remaining tissues would need to be adjusted to compensate.
This .pdf article from Scientific American gives a few interesting ideas concerning improvements to the human frame;
http://www.eebweb.arizona.edu/michod/Classes/182/182%202006/Better%20human%20design.pdf
assuming humans could be genetically engineered to live longer, the body could do with some improvements to ensure that they don’t suffer from wear and tear as much as unimproved people…
<69th reply>No one mentioned double-jointed back bones and a longer tongue yet?</69th reply>