humankind Q

If all humans were say 15-20’ tall on average, would the planet food supply and other necessities be able to provide enough for them adequately? Considering it’d take more food and bigger buildings, etc to accomodate them I wouldn’t think so, but I’m curious for any answers from knowledgable people here.

Is it strictly chance that our world is “human size” and most things are scaled to our size instead of dinosaur size?

Well food supply these days is more or less dependant on the effort we put into producing it. We currently produce about half again as much food as we need, and that’s with wasteful practices like grain fed beef and organic farming. It’s theoretically possible to produce sufficient food the whole world in an area of about 250, 000km^2. So I don’t think food supply would be the problem, althouhg diet could get a little bland.

The next thing to work out is what effect size would have on metabolism. Large animals generally have a slower metabolic rate pound/pound because of a realtively smaller surface area. So a human 3 times normal height may not need even twice as much food once they stop growing. This is hard to work out because a human of that size is physiologically impossible.

So then we need to look at shelter. Again, these days shelter is mostly a matter of economics. With high rise accomodation we could fit the entire human popultion into an area about the size of NY state IIRC. Triple this and you still have more than enough room. Again, the quality of life issue is the problem, not the resources available to sustain life.

The world isn’t scaled to human size, any more than it is scaled to dinosaur size. Many plants produces seeds far to small to be edible to people without the use of tools, while others produce fruits that are so high up and on such thin branches that a human without tools can’t reach them. Similarly most animals are too big, too fierce or too fast for humans to live on.

Conversely we are too big to dig protective burrows that don’t collapse. We are too big to be able to hide beneath the bark of trees. We are too big to hibernate during bad seasons. We are too big to survive on a diet of just grass seeds or just dad rats.

The oceans are too wide for humans to swim, desert areas are too big and dry dry, arctic areas too big and cold and so on.

The world is what it is. The use of tools has allowed humans to exploit a lot of resources that chimpazees can’t. That’s all there is to it. The world isn’t human scale. In fact it could be said that humans are just small enough to be considered prey by most predators while still being to big to take advanatge of most shelter. The world is defintiely not human scale.

Humans and other animals can’t just be any random size, because there are specific connections between, for instance, the strength of bones and their length and thickness, and many other factors. Consider the thickness of an elephant’s legs in relation to its height, for instance.

Another example: if you take any given object (the body of a man, for example) and double its height, the mass has increased by a factor of the cube, but the area of the skin only by the square. So a skin surface that was sufficient to cool a six-foot man is woefully inadequate for a twelve-foot man.

These and other physical constraints explain why all creatures are the size they are and not larger or smaller. This is the fallacy of science fiction films with giant ants or spiders, or giant or miniature humans, for that matter. The strength of the materials that insects are made out of can support them and that size, and that size only. Any bigger and they’d be crushed under their own weight. (To say nothing of the various physical processes such as respiration and circulation that wouldn’t scale up properly.)

A really great exposition of all this (and more) can be found in “Two New Sciences” by Galileo, specifically the Second Day of the dialogue. If you haven’t read Galileo’s works, you should, because he is brilliant (of course) and, unlike many other classical authors, eminently accessible and even amusing. Many of his important works are written as dialogues between three characters representing the received orthodox (usually Aristotelian) views, the commonly held opinions of the day, and Galileo’s ideas.

One could argue that Galileo invented the scientific method, and it is incredible to see him doing it in these books.

To be Dinosaur sized, Humans would need to be dinosaur-shaped- an upright bipedal posture in Earth Gravity would probably end in tears, bad backs, broken bones when you fall over-
look what happened to King Kong…

T-rex was bipedal, but carried its backbone more or less horizontal, with a balancing tail;
a giant human would need a radical redesign.
Food would not be such a terrible problem, although I expect that you could not support billions of giant humans easily-
after all, look at the way elephants degrade their environment when they become too numerous.

Thanks to genetic engineering, someone will probably try it somewhere a few thousands of years from now… perhaps on a low-gravity moon world,
although miniaturisation is more likely if you want to cram a large population onto a small spaceship or asteroid.
Reduce people to the size of dormice and they could exploit a whole bunch of new ecological niches.
They could even parasitize the giant people-
human fleas.

Miniatures might lose a bit of processing power in the old cranium, so perhaps this isn’t such a good idea.

SF worldbuilding at