Gene banks aren’t enough to save the world’s food

Starting with a new plant I will buy a few varieties whose descriptions suit my fancy. Then plant as many seeds as I have space for. Adapting plants is a numbers game. Some won't germinate, some will grow slowly, some will become diseased and some will be eaten by pests. None of those are suited for the local environment. Thin the planting to allow the strongest growers room. It should be obvious which ones to keep. Once you have the plants that started from seed best its time to start selecting for other traits. Traits depend on the plant but for food you should be selecting mostly for taste at first. For example, I am crossing one pea variety selected for wirey strong vines and purple pods and a couple others for taste. This is my third year with those and I am getting sweeter pods on wirey vines but the vines aren't quite as strong or tall. So, I planted some of the original wirey vine seeds to try pushing the line that way more.

Some trait selection is unintentional. The plants are going to adapt to you as well. They will adapt to how you plant, harvest, and save the seed. With my grains some of the plants are too short to harvest with a sickle comfortably. Those go in the eat or feed to chickens pile. Some also don't separate from the plants when I thresh by hand. Also to the chickens. What I am left with are seeds that were easier to process just by not being super careful to get everything. With biennials or clonal root crops you will also unintentionally select for plants that store well as you have to keep the roots over winter to plant them in the spring.

I started saving seed about 5 years ago so nothing has really stabilized into something that could be considered a new variety. But, I have seen the steps closer to my goals.

Purchased seeds are a narrow part of that plants gene pool. If they are open pollinated they were bred until most of the produced seeds make the same looking and tasting plant in a specific environment. Really, if you are gardening, you should learn how to save seeds unless you have a seed grower near you. If you save seeds you will also have more seed than you know what to do with.

All you really need space for is allowing plants to reach full maturity. Some plants, like carrots or radishes, get huge if left to seed. One fruit from most plants will give you more seed than you likely planted. Each seed in a fruit is a unique individual that was fertilized by a different pollen. Even with self fertilization the seeds will not be genetically identical.

We don't need every application of technology, but the rest is a fantasy.

Yeh, the mathematically correct way. There are only about 4-5 generations of humans on the planet at any given point in time. Only the youngest of those can create the next generation. If each generation is getting smaller than the previous because the fertility rate's low, why would you expect population to stabilize?

> Migration is a thing, so unless total fertility is sub-replacement,

Outsourcing your fertility to countries with rapidly declining fertility probably isn't a long term (or short term) fix for the problem.

> "functionally extinct" is a tad bit premature.

In less than 25 years, it will be global. Unless you believe that in a handful of African countries that it will stay above 5 forever, even though it was twice that less than 80 years ago.

> the fact of group size temporarily inducing stress-related infertility until a population is below

So, you believe that all the little girls who exist today, who grow up as only children, who have no aunts or cousins, who see their school teachers childless, all their role models childless... they'll grow up themselves and say "Wow, I want 9 children of my own!"?

I think you're confusing the models here. The moose don't have low fertility, it's as high as ever, but the wolves eat so many offspring, or the food sources so sparse they starve.

In the stress-induced models like Calhoun's mice, population never recovers. The mice become extinct. Even though there's plenty of food, plenty of water, plenty of entertainment. Even after the population crashes, and there's no overcrowding, even then their fertility rates are so low that they just go extinct.

I have no doubt that unless you're in your 60s, you'll one day come to understand that I was correct. This is coming, and nothing other than underwhelming horror at the thought of me being correct explains why you choose to argue about it. HN is filled with people who understand how to predict trends with lines on a chart, and you know or could quickly verify which way fertility numbers are trending. Which direction it is that they can only trend, at this point. "Functionally extinct" is indeed the perfectly correct term for this. It's what you call a species that still has living extant specimens, but for which there is no realistic way for the species to survive in the long term. That's humans.