AFAIK it all boils down to the fact that during embryonal development our cells, which at that point were just a blob of undifferentiated autonomous chemical machines, somehow managed to unanimously agree upon the cardinal directions (up-down, left-right, front-back) for future development - and thanks to this, we don’t have toes growing out of our ears.
Too bad evolution is blind, and now our windpipes and digestive tracts cross over. It works, but it would have been nice if choking wasn’t a thing.
Other examples of interesting (sometimes called ‘unintelligent’) evolution might be how we walk upright, leading to complications with childbirth and back pain, blindspots because of our optical nerve, and or that recurrent nerve that does a random U-turn.
Evolution is basically millions of years of patches without ever getting a rebuild form the ground up. It’s mostly ok, but some bugs stick around
Interestingly, the recurrent laryngeal nerve is looped around that way because the structure of the nerve grows in before the structures of the aorta and other large vessels fully grow in and orient into their correct position, so the nerve ends up looping around them.
We just walkin’ with a couple billion years of biotech debt in us.
I always thought that was a poor design. Aliens likely would find that disgusting.
What interests me is that I believe all warm blooded animals also share this trait. Not certain that is true but if so, wouldn’t that mean it evolved in a very early period?
Also what I find interesting is that the layout of humans to most animals is the same. A head with eyes then nose then mouth among with the brain behind it. Most of the organs are in similar locations. It seems strange that there would not be more variety.
This is just based on an offhand comment from a lecturer during a practical session during my time studying animal management in college, not directly from a biology lecturer so citation needed, but apparently rabbits don’t have a combined windpipe/digestive tract and it means that a blocked nose can kill them. So even if choking wasn’t a thing we’d have to worry about something blocking our noses and suffocating us.
Oh that’s actually a good point, so there are upsides as well.
Movies would also look really silly when someone would get killed by having their nose pinched closed
That 85% of DNA that apparently does nothing? Commented out.
It has a small function. A random gamma ray decides to absorb into DNA? Well, 85% chance it won’t matter.
My understanding is that on average a human will make malignant cell about once a year, but the other anti-cancer systems of the body deal with it. People that develop cancer had one of those cells escape the system. Without introns this would be a much more frequent event.
Similar idea: at work we were sintering metal powders together in a vacuum chamber, but had oxygen diffuse into the metal about twice as much as our limit to keep it strong. So the lead researcher took titanium powder that weighed a little more than twice what our work part weighed and put it in the chamber, and the oxygen level dropped to about half in our parts. After that he started making three parts at a time to keep oxygen levels down.
It’s not a reason for developing this way, but introns are great for familial testing. They don’t need to be preserved so they’re changing all the time. If we didn’t have introns, familial testing would have to be done by looking at several DNA or protein types. Blood type, what D2 receptor phenotype. What MTHFR phenotype, etc.
Sorry for long post but I love this topic: in all primates non-coding DNA, there’s the gene that makes vitamin C. Most mammals make their own, except primates and Guinea pigs. In primates, the vitamin C gene is broken at the same location. So, the chances of multiple species of primates developing this mutation at the same place is very low. They’d all have to develop this mutation at the same place and thrive over the other members of the species, and become the dominant phenotype, and all offspring consume enough vitamin C in their diet to thrive also. Every single primate!
Instead, it’s much more plausible that one primate or primate ancestor develop this mutation in an area where the food sources had plenty of vitamin C, and a population reduction caused this ancestor primate to be the sole ancestor of the remaining primates, which then evolved to become monkeys, apes, and humans.
The Guinea pig vitamin C mutation that causes it to not work? It’s in a different location than the primate mutation.
Edit: apparently some primates can make vitamin C. But most can’t, and the ones the can’t, the gene is broken at the same place.
I recognize several of these words.
(Jk thats very detailed and interesting! You seem really passionate about your work/study!)