Yrolg1 t1_jack5ch wrote

> As for the timeline, bipedality is far older than one million years before sapiens, and in fact arrives around three million years before the earliest erectus. Australopiths are decidedly bipedal by 5mya, there’s a strong case for pushing this another million years back. Erectus dates back to just barely 2mya.

There are different kinds of bipedalism. Australopithecus was not an obligate biped. Early homo were unable to run even if they were obligate bipeds. Erectus was the first hominin that demonstrated modern capabilities. This is what I meant by cursorial adaptions, i.e. adaptations for running, which are not derived traits from earlier primates and novel to Erectus onwards. Nuchal ligaments, Long bone length, gait, narrowing of the hip, extension of the achilles tendon and arched foot, broader heel and short toes. I'm unsure of any others off the top of my head. These traits would have appeared around 1.8mya, but erectus was a highly variable chronospecies so I said "over a million years ago" because I wasn't positive if they appeared all at once. If they were present in African erectus or Asian erectus, etc.

> Hair loss is a hazier picture because we still have basically all of the mammalian genetics for fur, and the adaptations seem to be substantially in hundreds of regulatory elements,

I wasn't actually counting hair loss as a thermoregulatory adaptation, because it definitely is more of a recent feature. Hair vs body lice and all. There are other adaptations which may have, or were, present. These include evaporative cooling, larger body size and its corresponding metabolic benefits and greater surface area (to prevent hyperthermia). The changes in gait and obligate bipedalism mentioned above also conferred metabolic/energy conservation benefits. Bipedalism itself can be considered such an adaptation, but it clearly didn't evolved in response to selective pressure for hunting, and that's the rub with much of this. It very well might be that we just evolved a kit that could be repurposed for a hunting style - and we're misunderstanding the cause and effect.

> Remember, this is all a position again the actual hypothesis coined “Endurance Running/Persistence Hunting Hypothesis”, not the occurrence of persistence hunting in human evolutionary history overall, which is incontrovertible. The hypothesis frames persistence hunting as the adaptive roadmap for bipedalism and hairlessness, and given the timeline of these elements it’s basically unsupportable.

This is a fair point. There is of course the question of when it appears, and I'd argue that there is support for its appearance well before sapiens.

> which is incontrovertible.

I disagree about how emphatic this is. I think there's ample support for its occurrence, of course, and I do believe it, but the primary source for it in modern humans comes from a single author (I don't recall his name, but it might be Liebenberg) writing about the San, who are very much a removed population operating outside their indigenous cultural norms. Moreover, there are several criticisms of his work the greatest that out of the dozen or two dozen observed persistence hunts, the majority of them were induced by the researcher and not spontaneous. So there's weak evidence that it was a preferred strategy, although from my own reading it's actually very successful compared to traditional hunting in that the great majority of hunts are successful and on average the caloric efficiency does well exceed a traditional hunt when factoring in success rate. Maybe they're just picky.

Maybe projectile weapons are just much safer and preferred. One of the postulates of the hypothesis is that persistence hunting was a response to the general inability of a hominin to take down non-exhausted megafauna through other means. Even with handaxes and spears, it would be very difficult, unless you're (literally) a Neanderthal. Perhaps the adoption of projectile weapons (the oldest don't predate sapiens, I believe 90kya) is what ultimately ended the reliance, if any, on habitual persistence hunting. Could Erectus even throw a spear? I seem to recall hearing something about their wrist being unable to rotate.


Yrolg1 t1_jab011j wrote

> This is called persistence hunting theory, and as I’ve mentioned elsewhere in this thread, it’s really just a theory at this point. There is virtually no material evidence of it being a consistent selection pressure across human evolutionary history.

There are numerous cursorial and thermoregulatory adaptions which make more sense within the context of persistence hunting, however. That being said, these made their appearance about a million years before h. sapiens was a glint in erectus's eye or definitive projectile weapons.


Yrolg1 t1_jaawbtx wrote

> It’s not really a shift in academia or anything as much as advances in genetic sequencing allowing us to see conclusively that the genetic makeup of all modern Europeans is around 1-3% Neanderthal dna

And the article says a Neanderthal ancestor 4 to 6 generations back. 2^5 = 32, or about 3% of his ancestry.