Miniature Humans?

Factual Questions
1

While watching a dog show the other day, it struck me that there is a great disparity in the sizes of the largest to smallest dogs. And humans bred them to these sizes. From a small terrier to a Great Dane is a tremendous difference in height and weight.

All pesky ethical considerations aside, could we breed humans to be fully functional and say 20 inches tall? I know that there are folks who are naturally of smaller than usual stature, so what’s the lower limit of human size.

Miniature humans could be useful for space flight. Less food and air required. IIRC, one of Heinline’s books had a jocky for a space pilot for that reason.

2

Nope - I’m pretty sure you’re thinking of C.M. Kornbluth and Frederick Phl’s The Space Merchants, in which the first human to Venus was a jockey because of his size (“They zippedme into the space ship!”)

Although Heinlein did have the first human into space being female for much the same reason (lightest and smallest in the pool of trained individuals) in his occasionally brilliant and frequently embarrassing screenplay for Operation Moonbase.

3

Lucia Zarate was apparently about 26.5 inches tall and fully functional. The shortest mature human on record seems to be Gul Mohammed, listed as 22.5 inches tall. So it is probable that functional adult humans, of normal intelligence, could be bred to approximately the size you suggest. Whether they would also have a normal life span, or would be able to reproduce and breed true, would be uncertain. Zarate died of exposure at the age of 37, while Mohammed died at the age of 40.

Breeding to a much larger size than normal would create many more problems due to stress on multiple organ systems. Most giants have been short-lived, and most large breeds of dogs have health problems of one kind or another.

4

CalMeacham you are correct about the book title. I always get confused between “Space Merchants” and “The Man Who Sold The Moon”.

Thanks for the links, very interesting. I know that giant dog breeds have a short lifespan, such a shame.

5

I don’t see why we couldn’t do it, given enough time. (Humans take such an annoyingly long time to reach reproductive maturity.) The OP specifies “fully functional” adults, so that would mean that simply breeding the tiniest humans that we can wouldn’t have satisfactory results. Usually if people are really really short, it is because of dwarfism or some other type of disorder. Much like breeding dogs, we wouldn’t only be breeding for size, but for other characteristics as well.

Now if we went ahead and started a breeding program with really short people who had no health problems or genetic disorders…

(Note: I don’t know much about genetics, but I’ve read a bit about dog breeding. If I get something horrifically wrong, please be kind.)

Here’s a scenario:

Let’s say that there is a worldwide agreement to send a group of colonists to Mars in 100 years. That time will be used to develop the necessary technology, of course, but it will also be used to breed extra-small colonists. Since 100 years is only enough time to have 4 or 5 generations, we wouldn’t reach the “lower limit of human size,” but it would be a start.

A few assumptions:

  1. Everybody who can be in the program will want to be in the program. Women will bear multiple children via artificial insemination. There will be no major fertility problems. Nobody dies before being bred.

  2. No genetic engineering will take place. Only good old-fashioned breeding will be used. Also assume that no major developments in genetic testing will occur. Like dog breeding, the program will depend on a variety of types of testing, but will also have the elements of trial and error and dumb luck.

  3. For simplicity’s sake, assume that the products of each generation will only breed with each other.

So the Program Engineers would launch a worldwide search for 1000 initial candidates for the program, say people 17-19 years of age. Call them Generation 1. The goal is to create a group of people of minimum size with excellent characteristics.

First, all people who have a “disqualifying factor” are eliminated. Anyone with any kind of genetic disorder is disqualified. Anyone who is, or has a good chance of being, a carrier of a genetic disorder is out. Anyone who has a strong family history of disease is out. Anyone who is not themselves healthy is out. Anyone who does not meet a minimum standard of intelligence is out. And so on.

Of the people who are not automatically disqualified, the shortest will be identified.* Let’s say 1,000,000 very short viable candidates are chosen.

The candidates will be then ranked according to various characteristics. Of course, height will be one of the most important ones, as will be a family history of shortness. Other desirable characteristics will include intelligence, creativity, athleticism, and all the usual stuff. Undesirable characteristics will include anything that might be unwanted in a pioneer society, from laziness to family history of twins.** (What might be considered desirable or undesirable is a whole 'nother thread.)

Then 500 male and 500 female candidates with the best combination of stature and characteristics will be chosen.***

Let’s say that G1 is bred over the course of a decade.**** Each breeding pair will have an average of 4 babies, giving us a G2 population of 2000. As they grow towards reproductive maturity, they will be evaluated and tested. A certain percentage will have disqualifying factors and will be dropped from the program. The remainder will be ranked like their parents, according to stature, good characteristics and bad characteristics. The top 500 males and 500 females in G2 will be identified and bred, producing G3.

Then G3 will be evaluated, and the top 1000 will be bred to produce G4. G4 will produce G5. Assuming an average generation length of 25 years and assuming my math is right, the G4s and G5s will be getting on a spaceship to Mars. The G5s will attain their adulthood on the trip, so you can consider the G5s the colonists. No new colonists will arrive for at least 100 years.

G5 will be the first generation to choose their own reproductive partners. Meticulous records will have been kept and the cultural taboo against incest has been maintained, having been modified to discourage romantic feelings between genetic “brothers” and “sisters.” In other words, G5s and their offspring will not be bred according to any program, but will avoid inbreeding as much as possible. Since there will be no Engineers running things, all offspring that can reproduce will probably do so. The population will grow.

So fast-forward to the time when G5’s grandchildren and great-grandchildren are being born. What will the Martian colonists look like? How small would they be? Will they be genetic minisupermen? Will new genetic disorders have arisen?

  • Would it be the shortest overall, or the shortest relative to their own populations? I’d vote for the latter in an effort to maximize genetic diversity. A short Norwegian might be taller than an average pygmy, but if he manages to be short among the Norwegians, you know he has some strong shortness genes in there. Mate him with a short pygmy, and there you go.

** Nothing’s inherently wrong with a family history of twins, but multiple births are inherently higher risk than single births, so we might as well breed it out of our colonial population.

*** Is a G1 population of 1000 enough to ensure sufficient genetic diversity?

**** Would it be better to have each breeding pair produce multiple babies, or to switch it up, having each baby produced by a different set of parents?

6

I’m not sure why you’d want to eliminate people with pituitary or achondroplastic dwarfism from your breeding population. Small dog breeds were produced from founder populations with exactly the same syndromes. They didn’t just breed the smallest wolves together for generations to produce chihuahuas, they chose pituitary dwarfs. And corgis, dachshunds and basset hounds were chosen from achondroplastic dwarfs.

If you want really small humans, the best bet would be to select pitutary dwarfs and select your breeding population from among those with the fewest secondary health problems from that dwarfism.

7

Plus, we know that our immediate ancestor, Homo erectus, bred itself* into miniature form. Homo floresiensis was 3 feet tall. They seem to be every bit as functional as their “normal sized” ancestors.

*using the term losely. It was natural selection that was the cause.

8

Sounds like there are lots of pitfalls, but could be done if the social and political need was there.

Thanks!

9

Breeding them smaller can produce problems as well; animals are “scaled” to a certain size; reducing them down can produce hormonal imbalances, physical deformities or misfits, et cetera. Note that the dwarfism–if I may use that politically-incorrect term–is general the result of some kind of developmental or congenital defect that causes a hormone malfuctions; most, er, extremely diminutive persons may have disproportionately short arms and legs but regular sized torso and head, or somesuch, so they aren’t just a scale model of a person. Attempts to miniaturize domestic animals (toy dogs, miniature ponies, dwarf elephants, et cetera) generally results in an animal with health defects, behavioral problems, and shortened lifespan. There appears to be no reason to expect that miniaturizing the brain in proportion would reduce intelligence, although there has to be a limiting case somewhere; a human with a brain the size of that of a fluke couldn’t have human-like intelligence.

There are, natually, other difficulties with miniaturizing people; you’d have to design tools, equipment, and interfaces for that scale. This isn’t so difficult with something like a keyboard–heck, a Blackberry would be the perfect size for the OP’s 20" man to begin with–but with a wrench or a drill you’d have to account for the dramatic reduction in leverage, inertia, and strength. Your micro sapiens may fit in your dollhouse-scale spaceship but probably couldn’t perform basic service. (It is impractical to linearly scale down tension fasteners or material thicknesses for structural reasons.) Then there’s man’s relationship to other animals; those who’ve read John Varley’s Steel Beach will understand what I mean. A Bichon Friese is just an annoying little dog to even a normal-sized child, but to a 20" human, it would be a major threat, as would predators like the domestic housecat or opportunistic scavengers like the rat. One would expect your miniature humans to be more sensitive to contaminants as well, which would be another negative.

As for saving lifesystem resources and food mass for spacefairers; it’s a valid point, but perhaps not as significant as it might seem. Any long-term space travel or permanent space habitat is going to have to be nearly closed circle in terms of environment; a vessel designed for interplanetary journeys isn’t going to be viable with CO[sub]2[/sub] scrubbers and an oxygen replunishment system; it’s actually going to have to be able to catalyze oxygen from waste on a continuous and reliable basis. So your reduction is on the scale or throughput of the equipment rather than total resources consumed, and the longer the mission or the larger the crew the less significant that is owing to economies of scale. (The economy in this case being power and volume consumed rather than build cost.) You would save food mass and habitable volume, but technologically speaking it’s probably easier to design for additional storage and space than to develop and manage a long-term selective breeding program or genetic modification to produce your dwarf subspecies, logistical issues notwithstanding. And the ethical and public relations challenges to developing your Ken & Barbie astronaut corps make it unlikely any such program would have popular support even if it were feasible.

The honest, dirty little truth about space travel is that from a cost vs. benefits standpoint it is easier, cheaper, and far less risky not to cart around blobs of protoplasm at all. We’ve gotten far more in science value from even our crude unmanned probes than we’ve ever attained from manned exploration, despite the restrictions of technology and the limited capacity for communication. There’s very little we can accomplish by adding even a well-trained and autonomous astronaut that can’t be better done by a robotic explorer, and owing to the enormous amount of work and design compromises it takes to transport and protect a human from the unfriendly environment of interplanetary space or the hazards of exploring the vacuum environment of most moons, not to mention the caustic atmospheres and crushing gravity of most planets.

There are only two genuine reasons for manned exploration and colonization; one is to further secure the future of humanity by getting a significant pool of human genes away from any catastrophe that would destroy the Earth, and the second is…pure hubris, a desire that Man (and I use the term in the gender-neutral form) be the intelligence to explore and dominate the Solar System, the galaxy, et cetera, rather than the increasingly autonomous tools of humanity. I daresay most manned exploration enthusiasts do not regard a computer–not even the Heathkit machine they built themselves–to be a worthy successor or descendent, and envision Star Trek-like utopia-esque spaceships to whisk them to far-flung exotic locales. This is probably hopelessly unrealistic–in order to perpetuate our legacy in the hazards of space, we’ll either have to pass the torch on to synthetic organisms that are more robust, or we’ll have to modify ourselves to accomodate those conditions. Maintaining Earth-like conditions in thin-skinned steel cans sans the protective atmosphere and magnetosphere of a planet is an expensive and likely unviable situation in the long term, even for miniaturized successors.

Stranger

10

Shoot. Both my kids were about 20" tall when they were born, and they seemed just fine. Of course, I haven’t had any luck getting them to stay that way.

11

Have you tried the Bonsai Kitty technique?

12

In case people didn’t catch that, the remains of a group of Hobbit People were found in Indonesia a couple of years ago. The regular human population seemed to know a lot about them even though the remains found were thousands of years old. Islanders claim the little people were still on the island 100 years ago and they could still mimic them.

The hobbit people only grew to three feat tall. Last I heard, it wasn’t conclusive that they were descended from Homo Erectus.

13

Couldn’t we just tinker with a 1920s-style Death Ray and make it into a shrink-o-ray? Quicker results; better lightshow.

14

This discover is still quite new, and doubtless needs a lot most study. The “dwarf” Erectus population theory seems to be the most reasonable, and I’ve seen the skull and agree that they look very Erectus-like. But you are correct in saying that that this still somewhat controversial. I hope there are a lot more finds in the future, maybe some that are intermediate in size between the Hobbits and mainland Erectus populations.

15

There’s also the colony of tiny people bred and raised to be comfortable on Venus in PKD’s The World Jones Made.