What if australopithecus was carnivore?

Everything changes. :-) So much of our history is the outgrowth of the creation of agriculture, from having where there were plants amenable to domestication to start with all the way to finding and controlling new farming lands to settle in. Jared Diamond lays this out wonderfully in "Guns, Germs and Steel". The question is, since animal husbandry is more resource intensive, were we carnivores how much population could we maintain? I doubt anywhere near as much as we have now. Serious animal husbandry would be delayed because growing crops for animals was an outgrowth of growing crops for ourselves.

Take einkorn & emmer wheats, for instance. There's evidence to show they were evolving towards their modern forms in which the grains were more strongly attached to the stalk which allows for much easier harvest than if it just fell off easily onto the ground. This made palaeolithic, pre-agricultural humans forage for them more, and that in turn spread the plants with that variation around to larger areas and made it more successful.

But carnivorous ancient humans wouldn't be doing that so feed crops don't get developed until much later when some enterprising person says "Hmm… we've been breeding these varies of animal for better meat traits, I wonder if we can do that with the plants they eat as well?" Of course, Homo carnivorii wouldn't be as attuned to the natural cycles of plant growth like we were since it hadn't been necessary for them to survive. So if our technology develops apace but lacking the agriculture stuff, I'd think we'd have a good chance of killing off a lot of animals and putting our own survival in peril through extinction of prey if ecological management doesn't get discovered fairly early on. We may be smart & hve language and oral traditions, but recovery after the crash might take so long oral traditions are not good enough and we could drive ourselves extinct if we expand across the globe and drive all the megafauna extinct through over hunting before we learn animal husbandry because we'd never be able to fall back upon browsing for plant foods when herds are thin.

But let's say that through happenstance Homo carnivorii discovers eco management and learns to not only ration themselves but also to rotate their herds through pasture lands in a conservationist manner.

Rather than owning the land, I'd speculate that we'd "own the herds" and that a world in which everybody is like the nomadic Mongol and Turkic tribes of the central Asian steppes and follow them around and mostly only getting into wars when those herds compete for pasture land. The "centres" of civilization would be the savannahs and plains because thats where we see herds of mammals gathering. There may be more biodiversity in the forests and jungles, but the mammal herds also tend to be smaller in number and more dispersed (they also tend to be more sedentary than migratory).

Cities as we know them would never develop as there would never be that many people. Pre-agricultural global population estimates centre around 5 million people so I'd speculate the until some smart chap thinks up the idea to grow crops and support larger herds we'd be limited to 50 million Homo carnivorii. There's be a few mining settlements because after flint & stone somebody will discover metalworking. I suspect it would be one of the forest civilizations that depends on sedentary deer herds but then once the larger steppe civilizations get wind of the technology they're the ones who will develop iron age industry.

Developing feed cropping agriculture will be tricky. Taking a few pots, growing plants and selectively planting only the biggest seeds/fruits would probably show results in as little as a decade to show the idea is possible, and then clear a few small, garden-sized plots of land to grow just that plant and show that growing in bulk is possible. But this now is where it gets tricky. While they may be able to grow the crop more densely than the wild it's still not going to be close to OTL modern crop yields and it would take many, many acres of tillage to get enough crop to feed even a small herd through the season in which they would normally migrate elsewhere. A 1600lb steer gives about 600lbs of meat of various cuts and Homo carnivorii would probably eat 5lbs a day on average (based on a 350-500lb lion needs about 11-15lbs a day). If Homo carnivorii is adapted to eating only ever few days, 20lbs at a time, that steer would feed 30 people, a small nomadic group, but unlike plant foods it is more difficult to preserve so you don't have to eat it right away. So 15 people, one steer a week, 52 steer each year. Cows give birth say once a year and it takes two years for an animal to mature so you'd need 104 cows, 52 giving birth in alternate years in an established herd to keep up with demand, so you'd have 100 cows plus 52 born that year plus 52 born the year before plus 52 that will be slaughtered this year, so a minimum her of 260 cattle barring accident or disease or theft or predation to feed 15 Homo carnivorii.

That is much larger than OTL family farms in the middle ages and is going to take the tilling and maintenance of hundreds of acres of wheat to feed that herd with the much lower yield of palaeolithic crops. It takes about a day to plow an acre with a team of oxen, about a week by hand. This mini-tribe of 15 adult people, 10 teams could plow 300 acres in a month. I'm assuming that once the inventor goes from test-breeding wheat in clay pots for a few years and then learns about clearing and tilling land for the next step they will already have had ox-drawn carts and easily make the leap to oxen pulling plows. Problem is, I'm not sure that palaeolithic crop yields would mean 300 acres is sufficient.

But it's going to have to be an influential person doing this to put hundreds of o acres under plow with no ingressions by the herds of other tribes. Heck, the eco-management of migratory herding might even have become part of the religious aspects of society and invoke anger at a heretical action. It would take a few thousand years before crop yields got them down below even 200 acres to take care of a 300 head herd.

I would guess that in the ATL, by our time it would still be late copper or early iron age technologies with very early stage feed cropping in a few scattered places.