Alternate paths to orthostasis

Question

I've asked a whole array of questions, so far, centered around an ongoing project of mine that features a world, in an alternate evolutionary timeline, where a variety of well-known mythological creatures live alongside humans.

One of the species I'm now considering to include in this project are werewolves - not shape-shifting ones, but just wolf-like creatures with a human-like, or orthostatic, posture.

I've seen a few similar projects (As in "plausible fantasy creatures" projects) with werewolves, and all have made them orthostatic descendants of wolves, often without providing any explanation why a group of cursorial quadrupedal hypercarnivores even evolved to stand upright.

Instead of humanoid wolves, I'd like to go for something a little more plausible; giant, bipedal baboons. Given that they are primates, it seems more likely that they might develop orthostasis (Since we did), and they have a very dog-like head, which could be developed into an even more wolf-like one.

I know that humans evolved orthostasis by being descended from arboreal primates which were driven into a savanna habitat, where they were forced to become cursorial, but could not become quadrupedal since their ancestors had hands, and could not take up bipedalism with a theropod-like gait because they were tailless.

However, are there any other reasons, set of events, or evolutionary transitions, that would make a population of baboons or baboon-like primates evolve to be bipedal with an upright back, besides that of humans? The main reason for this is just that I'd like to "shake things up" a bit, rather than copying the evolution of hominids.

I guess that somehow making the ancestral baboons be tailless would be a good idea, to avoid ending up with these:

Source: https://speculativeevolution.wikia.com/wiki/Raboon

Another key thing is that baboons already live in the savanna, or at least Olive baboons and Chacma baboons(the ones with the most dog-like heads) do, so any transition to bipedalism will be different to humans'. An important part of the end result is that they still have fur - humans lost most of their hair after becoming cursorial.

Answer 1

It's thought that hominid bipedalism was ultimately a result of resource scarcity; we had to travel a long way between calories on the savannah and our bipedal gate was more efficient than our quadrupedal one so we had to walk upright to cover the distance. This led to better upright walking being a survival trait that was reinforced generation on generation. To have this same effect in baboons you need them to be fussier eaters; as it is their generalist diet means they don't need much travel to find food even in quite harsh environments. And you need them to be less efficient quadrupeds because as is they're extremely effective as quadrupeds.

This might be accomplished by striping the savannah of ground level foods, either by flora species reductions or dietary adjustments. If baboons had to reach and climb for their food more often than not then longer arms and a more versatile hip and shoulder joints would become advantageous reducing their specialisation based effectiveness as quadrupeds.

Answer 2

Sometimes all you need is a stomach flu (and possibly some brain damage).

In 2004 macaque in an israeli zoo got sick and had, in her care team's words, a near death experience (go figure). After recovering she would walk exclusively upright.

The original links from newspapers from back then are sparse and most don't have pictures, but the story is preserved in this wiki.

In a way it makes sense. Maybe it was our diet, or something in our gut, and not anything else that got us walking upright. Whenever I hear proponents of the paleo diet talking:

"Don’t worry about getting enough carbohydrates (...) you don’t NEED any at all. Contrary to popular belief, there is no lower limit to the amount of sugar your body needs.”

-Dr. Ron Rosedale

... I can't help but picturing those people knuckle-walking and screaming like chimps.

So add some potatoes to your hominid species diet and watch the magic. They'll be walking upright before they develop larger brains.

Answer 3

Do your baboons have to become truly upright to fill the bill? A werewolf is a creature of terror, and humans are not always reliable narrators after a terrifying experience.

A larger baboon, hostile to humans and with evolved nocturnal habits (perhaps due to its poor relationship to humans) might do the trick. If a peasant encountered a 5 foot tall baboon at night, and the baboon rose on to two feet to attack, the resulting tall tale might end up sounding pretty much like the description of a werewolf attack.

Especially if the nocturnal baboon adapted to live in caves during the day, and lost much of its body hair and became albino as a result. An angry 5 foot tall albino baboon with the mange would certainly scare the living heck out of ME.