(Sorry, today’s clearly my day for idle questions.)
Humans have a tradition of tinkering with the animals we breed. We developed horse breeds with vastly different coat colors. Hens that lay eggs virtually every day. Cows with all sorts of horn shapes.
Obviously this goes for size, too. Look at Great Danes versus chihuahuas. Those smallish pigs some people keep for pets. Mini horses. And so on. And this without high-tech radiation treatments or advanced DNA tinkering or anything. We just bred the ones with the most of whatever trait we are looking for together and picked the best of the resulting litters and then bred them together and so on. Easy peasy, cavemen could do it.
So, can it be done with basically any animal that we can control the breeding of?
Personally, I think it would be fun to have a herd of three foot tall giraffes. Let’s get on it?
I wanted similar things when I was a kid (My idea was a puppy that never developed adult dog characteristics remaining extremely cute until death) but I was told by my aunt that it would be really cruel to the animal, selecting for small giraffes could lead to all sort of genetic problems in the breed.
To answer your question, yes, within reason. I don’t think you could breed a mouse-sized elephant, no matter how hard you tried, but for most physical characteristics, given enough time and effort, you could modify almost any animal.
It’s not quite that simple. There are limits to how directly scaling works.
For example, a giraffe is able to be so slender and yet tall because of the properties of bone and muscle. Scaling those might make bits too fragile. Or the genes controlling size also control the length of legs and necks.
Think of dwarf humans. They tend to have full-sized torsos and stumpy legs or legs and arms. That wouldn’t make much of a giraffe.
If whales could evolve from hyena-like land animals I guess we could make mouse size elephants too, it’s just a matter of time and money (which I grant would probably run out before the objective is achieved)
Sure, but I’d imagine the problem would be the time scales involved.
The way it works is that you breed the smallest ones together in each generation. So they get a little smaller each time, hopefully.
Over a long time, this’ll end up with a smaller animal. You see this in food-limited environments where the smaller animals survive, putting evolutionary pressure toward smaller animals.
But to get an animal to any sort of reasonably small size like that, it takes a LOT of generations.
I’m certain you could eventually, or at least your descendants could. Elephants evolved from ancestors the size of a hyrax or shrew, and after becoming gigantic made it back to the size of a dog:
In Sicily, where dwarf elephants were slightly larger - the size of a pony - we have evidence that the shrinking happened quickly, in about 40 generations or a little over a thousand years. Human directed selective breeding could probably achieve smaller sizes and a faster turnaround.
In the fox experiment, it only took about 30 generations (a little less than 30 years) of selective breeding to produce dog-like foxes: Domesticated silver fox - Wikipedia
By 40 years on:
Trut wrote in 1999 “that after 40 years of the experiment, and the breeding of 45,000 foxes, a group of animals had emerged that were as tame and as eager to please as a dog.” Fitch described the tame foxes as “incredibly endearing”.
Elephant reproduction cycles are much longer, though, maybe taking 10-15 years to reach sexual maturity. 30 generations of that might take half a millennium. That’s assuming we couldn’t use GMO editing along the way to help speed it up, just selective breeding.
Well, not anymore - they’re all dead now. But the diagram is of a real fossil species of Paleolaxodon.
The Phillipine Dwarf Elephant seems to be in some dispute; it’s only known from a single tooth which was identified as a molar, but it may in fact be a different tooth which would have come from a larger animal.
The Sicilian elephant is known from better material. There were also dwarf mammoths on islands near California and dwarf stegodons on Flores at the same time as dwarf hominids.
This was in fact part of the domestication process for both dogs and cats. Domesticated animals are more childlike than their wild cousins. This seems to have been a byproduct of selecting animals for being more friendly and obedient towards humans.
