312

Through selective breeding and misplaced import laws, we only ever get to see Russian dolls that are "aesthetically pleasing". In the wild, it is relatively common to get a "double-yolker" - that is, sometimes when the outer layer dies, there are 2, or perhaps 3 dolls inside. Since these dolls are often a little misshapen when compared to the outer layer, ...


202

Assuming that it's purely random, let's consider where these people would probably be. Taking the percentage of the population each country represents, we get: China: 18.2% = 6.37 people India: 17.5% = 6.125 people America: 4.29% = 1.5 people Indonesia: 3.43% = 1.2 people Pakistan: 2.78% = 0.93 people ...etc. The percentage keeps going down. This means ...


187

It's HF radio, or nothing The odds of anyone meeting again are almost exactly equal to the odds of at least two being either radio hams, or able to learn the skills from books. The population density of 35 people worldwide is so extremely low that the odds of finding someone without the benefit of global communications is practically zero. Strategies like ...


126

In the deepest, darkest, hidden places in the forest dwell the Queen Dolls. Rarely seen, these creatures resemble a normal Russian Doll only at the tops of their vast, misshapen bodies - their lower halves more closely resemble a nightmarish wooden bee hive. Riddled with thousands of cells, they disgorge the normal Russian Dolls commonly found in the ...


96

Actually, there is an organism on earth that is vaguely similar to the Russian dolls that you describe. The volvox: Individual volvox cells, a kind of freshwater algae, reproduce in the conventional way (more or less), however, they also collect into spherical colonies (called volvocates, I think) with a tiny opening at one end. These spheres can reproduce ...


73

The different causes of death are the biggest issue here. Humans will lose a lot of children to disease, elves don't seem to suffer from this Humans lose fertility early then die fairly young, again not a problem for elves Most of the death rate for elves appears to be wars, in a time of war they'd need a birthrate approximating that of humans just to ...


63

I'm going to respond to this with a framing challenge, because as it stands I think you're asking the wrong question. The issue is that the modern industrial world is a product of population DENSITY rather than total population. This may seem semantic but in a post-apocalyptic environment it's very meaningful. Modern industrialism depends on and benefits ...


56

There's not a lot to do in space, so bored people in close quarters resort to what they always do, and have large families as a result. The small families that are the norm in today's developed world are a historical anomaly. In rural China, it was nearly impossible to police a "one child" rule until they became more economically developed, because rural ...


55

Low natality rates. They would live long, but procreating a child is a very rare event for all couples. That should balance the lack of aging, if deaths due to other reasons are not too frequent.


54

This is an interesting question. Obviously, just walking about and hoping to meet someone is fruitless, the chances are just ridiculous. What you would want to do is communicate. Now we know how many people survived and what the likely distribution is, but they do not. From the perspective of a survivor, everyone around is suddenly dead or disappeared. ...


49

I figured, since a lot of people are bringing up the Birthday Problem, I'd add a separate answer just for discussing it. Simply put for those not familiar with it, the idea is that based on probability the actual number of individuals needed within a sample before overlapping becomes nearly certain is far less than the actual number of possibilities. The ...


49

(This answer supposes that electricity and the internet survives for a day or two) Either a couple of days, or many months, if ever. CALLING OUT TO ALL SURVIVORS Hello! Everybody in the world has disappeared. Considering that you are reading this, electricity, the internet, a search engine, and Stack Exchange must still be working, and you had the state ...


49

Yes, but not in the way you are thinking. One way this could happen is if some killer fungus starts growing unchecked throughout the planet, on land and sea. By killing all plant life it would destroy every other ecosystem, so it would wipe out all mammals. It would also practically wipe out all other members of the animal kingdom. This is part of the plot ...


43

Attrition Also one of the reasons rural medieval families were usually large ones. Because space stations represent the frontier, the most hazardous jobs and the workforce handling those jobs would be found there. A high attrition rate could come from pioneering exploration into unknown and likely dangerous environments, technology being inadequate to keep ...


42

Regenerate the top part. The splitting doesn't actually kills the doll - just its bottom half. The bottom half becomes a nest for the little doll that was gestating on the inside of the "mother doll" for a bit, until it can go around hunting for cookie crumbles for itself. The upper part, on the other hand, shrinks a bit in size and regenerates. After ...


39

Assumption #1: Somewhere between 40 and 50 years. Any girl babies just conceived before the Curse was thrown down will have somewhere between 40 and 50 years before menopause sets in and they will no longer be able to easily bear children once the Curse is lifted. Here I assume that Evil Villain Bad Guy was smart enough to include cryogenically preserved ...


38

An easy way to justify large cities-only settlements is to have specific requirements that can't be scaled down too easily. One example would be to need a domed environment, easier to maintain in large clusters and difficult for small detached locations. Another example is need of a perimeter confinement to keep out "unwanted guests" (e.g.: large dangerous ...


38

Budding and out-growing. Budding: each outer doll, once in a while, produces a bud, which in this case is a tiny Russian doll. Once it detaches from the mother body, it starts living on its own. Out-growing: once the doll has eaten enough, it grows, on its outer, a new shell. Think of it like the trees growing each year adding a layer to their bark. At the ...


35

107 Billion according to the Population Reference Bureau. Details Here Must warn that this can only be guessed and is based on arbitrary definitions of human. What we call hominids (i.e., humans) go back further than the supposed 50,000 BCE, but you can do a rough estimate of 600,000,000 max at any point (the maximum capacity of Earth to handle Hunter ...


34

San Andreas makes big boom! many little booms So, the Big One is finally about to happen: Scientists have seen the pressures spike, all the signs are screaming DOOM! Fortunately, just hours from disaster, Bruce Willis and friends descend into the depths with an Elon Musk designed HyperDrill and stuff the fault line with HyperGlue to the tunes of Aerosmith. ...


34

Living in a sealed environment requires everybody to be educated. You can't risk someone dumping lubricants in the toilet because that's an easy way to get rid of them, etc. Education means literacy, literacy stabilizes spelling. Computers will be common and the total populations will be relatively low. Would it be possible that names are selected to be ...


32

This idea that people with eternal youth would be constantly reproducing is not necessarily accurate; nor is the idea that producing any more than 2 children per couple going to result in population growth. Additionally, China's one child policy has had massive repercussions for the State that are only just now starting to bite. In reality, population sizes ...


31

Historical context of population growth Population expanded significantly in the middle ages, between the low after the ravages of the Justinian Plague of 541-542 to the high middle ages peak of ~1300 before the Little Ice Age brought famine. According to the Medieval Sourcebook (possibly the best thing on the internet), the population of Iberia went from ...


31

Just look at reality If you have educated women and a good healthcare system such that kids make it to adulthood in one piece by and large, you won't need to worry much about overpopulation -- individual family planning will take care of that for you, as it does IRL. If worse comes to worse, you have family planning consultants who will help prospective ...


30

Weather Plains provide little to break winds. So your plains may be windswept regions. If your tech level is low, that makes building homes harder. The winters might be too harsh. Especially if there are winds. If your settlers travel into the plains, then freeze to death because no one has proper winter clothing or insulation... There may be too much ...


30

Aging is not necessary to maintain their low population. No population can grow without limit, and in the animal kingdom, most animals die before they would otherwise die of extreme old age. These are the things that limit population growth. Food stocks. Regardless of your will to reproduce, if you don't have enough food, you can't grow new humans. ...


28

Yes. At least in a science-fiction setting, you can construct a plausible scenario where this might happen. If there is one child per couple on average, the population will halve with every generation. This would result in a long, slow decline. For example, after 14 generations (say, about 420 years), the Earth's current population of 7 billion would have ...


28

Not as long as you might think It depends on the assumptions you're willing to make. With the world population growing at a vigorous 2% per year, there would be a trillion people alive in around the year 2260. The fastest human population has ever grown in recent history was 2.2% per year in the early sixties. This type of scenario would correspond to a ...


28

Ordinary meat takes a lot calories to grow. For example you have to feed a cow 9000 calories for it to gain a pound, and a pound of beef provides roughly 1100 calories. Consuming plants directly would still be able to feed a much larger population that any kind of meat, even if you increased the efficiency of lab meat by 2x or 3x over regular meat. The ...


27

Research suggests that the number of children people have is strongly affected by the economics of children. When having many children is economically advantageous, birthrates go up, and when it's not, birthrates go down. During most of history, the cost of raising children to successful adulthood was relatively low and the benefits of having a large family ...


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