Lol. That's good. So true. I didn't think of that. It's more like "unconscious" nature that is usually more efficient instead of civilizations. Although I don't understand why some crop genomes have so many more genomes than humans. Maybe wastefulness is everywhere.
Are you talking about polyploid genes? Having more copies of each gene per cell nucleus is effectively RAID: it protects against copying errors, and therefore against genetic disorders and cancers. This does have the side-effect of increasing the size of the nucleus of each cell, which is a problem if you're an animal with cells that need to float around in a blood stream and squeeze through tiny capillaries—but not if you're a plant, with all your cells locked in place.
That's also an important consideration I hadn't thought of. The plants can have the cell size constraint relaxed because of their different morphology / physiology.
In fact, it came from me looking at human and other vertebrate genomes, and then looking at some reference "crop" genomes and seeing multiples as many genes. I didn't know if they are polyploid copies as you say or not tho it could have been. I'll try to find the links where I saw these numbers (from a few years ago now) and update.
( there are many with over 30,000 genes ( cf humans < 20,000 ) and there are a few big ones ( Aegilops tauschii (Tausch's goatgrass) has 4.3Gb ), and most are more than 200 Mb ( cf fruit fly is around 180Mbp )
The weird thing is that genome size is correlated with "complexity" in non-animal world too. With fungi and so on having smaller genomes generally than large plants. All this seems weird because my assumption is that animals are more "complex" than plants. So either there is a lot of redundancy there or plants have some kind of unseen complexity. It would be cool to see models that try to quantify the explanations of large genomes given here by others ( error and viral resistance and freer nuclear sizing ) and see if those models can account for the sizes somehow, or if there might be more to the picture.
Another possibility is that genomes grow with genetic manipulation so cross-breeds have bigger genomes. But what does that say for humans? Are we the result of genetic breeding as well?
To put a finer point on it, the limit on cell size is closer to the definitional difference between what makes something a "plant" vs an "animal" than almost anything else. Plants, due to their stable tissue structures, don't need to worry about their cell size, and therefore don't need to worry about unbounded DNA growth. Because of this, they have evolved to take advantage of having "more" DNA. Yes, polyploid plants are generally healthier, because plants expect polyploidy. But even without polyploidy, plants have large amounts of "specialized-use" genetic material, libraries of specific responses (e.g. immune responses) to specific problems (e.g. parasites) that may have only existed millions of years ago. They can just keep all these one-off solutions around, evolving to protect themselves against one more thing at a time.
(This is also why plants tend to be full of weird organic molecules like terpenes, which are beneficial to nearly every animal alive today: those chemicals probably protected them from something at some point, and the genes responsible for making them have had no reason to be shut off since then.)
But animals, with a finite limit on gene-base size, must solve problems differently. Animals evolve along different lines—polyploid mutations usually result in non-viable offspring for animal species, because animals frequently have mutations that assume diploidy, with complex machinery to favor better vs. worse versions of each diploid gene using silencing or epigenetic methylation. And more generally, animals evolve solutions to whole classes of problems that have compact genetic representations. We don't have a million custom immune responses; instead, we have xenograft rejection genes, T-cells, livers and kidneys, saliva and stomach acid, the sensation of itching, skin that sheds and skin oil that clears pores, and put together, those mechanisms handle 99% of cases just fine.
And often we don't need any of those; the primary "solution" that animals have to almost every problem, is just the ability to move away from the source of the problem. If there's a predator, you can just run away. You don't need to know what the thing is, to run away from it; you just run away! Universal solution! To do that, we need a lot of things: not just limbs, but sensory organs, to know where we are and where the predator is; and nerves, to link the two; and even some sort of instinct for what predators exist, or memory to record sense-fear associations. But all those genes still take up far less space than immune proteases individualized for every bacterium and fungus on earth.
a genome is a dartboard, a virus is a dart, having a giant dartboard means the dart is more likely not to hit a bullseye (really big. so big you can't even throw the dart far enough to reach[1])
