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Most of human dna is garbage, it doesn't code for anything. A full 8% of the Human genome is just viruses. If you want efficiency, there are viruses with only

Most of human dna is garbage, it doesn't code for anything. A full 8% of the Human genome is just viruses. If you want efficiency, there are viruses with only 2 genes. 2. 1 for their shell and one for the enzyme that copies dna...

echelon 6y ago
> Most of human dna is garbage, it doesn't code for anything. It's not garbage. If you remove it, you won't have a functional human. "Junk" DNA does quite a bit: Shield from damage, change spatial conformation of DNA in 3D space, change histone wrapping offsets, provide a basis for gene duplication and mutation (which is fertile ground for evolution), etc. The spatial effects have a nonnegligible impact on gene transcription. Imagine gutting your PC and throwing just the essential components into a cardboard box and expecting them to work. A better analogy: do the same to an automobile factory, because that's a better proxy for a cell. > A full 8% of the Human genome is just viruses. Which have contributed to our evolution. The placenta has been theorized to be of viral origin. The immune system, which in places uses complex gene rearrangement, also benefits from viral genes.
- jhbadger 6y ago
  We know from the Fugu (pufferfish) genome that vertebrate genomes can get away with almost no junk. And before people say "well, that's just a fish, not an amazing human", realize that from the larger evolutionary perspective, the difference between a fish and a human is almost nothing. There is no particular reason to imagine that "you won't have a functional human" without the vast majority of junk DNA. Obviously there would be ethical concerns for doing this experiment, but the fact that onions can have huge genomes and fish small ones is pretty good evidence that there is no correlation with the amount of junk and functionality.
  - echelon 6y ago
    An organism can evolve without junk DNA. But to take human genetic code and remove the junk would change transcription that currently expects it. Portions of the DNA that might be wound would be exposed, or vice versa. It impacts DNA repair, transposition, promoter kinetics, etc. It's a vargus nerve situation. We evolved around our junk DNA. It's a part of our machine.
globular-toast 6y ago
Some of them, like HIV, encode multiple genes in overlapping sections. If ever there was a case for intelligent design it would be in these viruses, not complex organisms with huge genomes like plants and humans.
- ericbarrett 6y ago
  Wouldn’t a virus be hard-selected for short, efficient genetic code? They are so tiny that extra base pairs must have an enormous effect on their physical and mechanical condition.
  - globular-toast 6y ago
    It really depends on the virus. Some like the famous bacteriophages have relatively large DNA genomes and they are the most abundant viruses on Earth. There are also giant viruses with genomes bigger than some bacteria. It's all very strange. This leads people to think these viruses evolved via different mechanisms. Some are likely ancient and have been around since before other life started using DNA while others seem to be more like highly specialised bacteria that have lost their own ability to reproduce (hence rendering them viruses).
yters 6y ago
I believe the ENCODE project has shown the junk dna hypothesis is not clearly true. A large portion of the genome codes for something, somewhere above 70 percent, even if most of it doesn't create proteins directly. As an analogy, a piece of well written code often has a lot of extra info not directly tied to its core function, such as logging, error handling, etc. Much could be removed without impacting the core function, but that doesn't mean it is junk code.

echelon 6y ago

> Most of human dna is garbage, it doesn't code for anything. It's not garbage. If you remove it, you won't have a functional human. "Junk" DNA does quite a bit: Shield from damage, change spatial conformation of DNA in 3D space, change histone wrapping offsets, provide a basis for gene duplication and mutation (which is fertile ground for evolution), etc. The spatial effects have a nonnegligible impact on gene transcription. Imagine gutting your PC and throwing just the essential components into a cardboard box and expecting them to work. A better analogy: do the same to an automobile factory, because that's a better proxy for a cell. > A full 8% of the Human genome is just viruses. Which have contributed to our evolution. The placenta has been theorized to be of viral origin. The immune system, which in places uses complex gene rearrangement, also benefits from viral genes.

jhbadger 6y ago
We know from the Fugu (pufferfish) genome that vertebrate genomes can get away with almost no junk. And before people say "well, that's just a fish, not an amazing human", realize that from the larger evolutionary perspective, the difference between a fish and a human is almost nothing. There is no particular reason to imagine that "you won't have a functional human" without the vast majority of junk DNA. Obviously there would be ethical concerns for doing this experiment, but the fact that onions can have huge genomes and fish small ones is pretty good evidence that there is no correlation with the amount of junk and functionality.
- echelon 6y ago
  An organism can evolve without junk DNA. But to take human genetic code and remove the junk would change transcription that currently expects it. Portions of the DNA that might be wound would be exposed, or vice versa. It impacts DNA repair, transposition, promoter kinetics, etc. It's a vargus nerve situation. We evolved around our junk DNA. It's a part of our machine.

globular-toast 6y ago

Some of them, like HIV, encode multiple genes in overlapping sections. If ever there was a case for intelligent design it would be in these viruses, not complex organisms with huge genomes like plants and humans.

ericbarrett 6y ago
Wouldn’t a virus be hard-selected for short, efficient genetic code? They are so tiny that extra base pairs must have an enormous effect on their physical and mechanical condition.
- globular-toast 6y ago
  It really depends on the virus. Some like the famous bacteriophages have relatively large DNA genomes and they are the most abundant viruses on Earth. There are also giant viruses with genomes bigger than some bacteria. It's all very strange. This leads people to think these viruses evolved via different mechanisms. Some are likely ancient and have been around since before other life started using DNA while others seem to be more like highly specialised bacteria that have lost their own ability to reproduce (hence rendering them viruses).

yters 6y ago

I believe the ENCODE project has shown the junk dna hypothesis is not clearly true. A large portion of the genome codes for something, somewhere above 70 percent, even if most of it doesn't create proteins directly. As an analogy, a piece of well written code often has a lot of extra info not directly tied to its core function, such as logging, error handling, etc. Much could be removed without impacting the core function, but that doesn't mean it is junk code.