CARTA: What Was Lucy’s Impact on our Understanding of Bipedality, Diet, and Encephalization?

[@gloriaharbin1131]

This was great! Thank you for sharing your knowledge!

[@GustavSvard]

This was a really good lecture. Really good. Explicitly mentioning and correcting assumptions and theories that were what I learned in school and from watching documentaries on human origins in the 1980s/90s.

[@jfjoubertquebec]

I wonder what drove bipedality? Dancing perhaps? 🙂 Great talks!

[@TexRenner]

That's my new favorite theory.

[@GustavSvard]

When dancing skills becomes part of attracting a mate, then it would be a driver in evolution wouldn't it? :D but hard to differentiate from skills at hunting when looking at the bones? :)

[@kuukeli]

interesting video

[@mrpocock]

Do we know what locomotion we inherited from our ancestor with chimps? As i understand it, they evolved their knuckle walking after that split.

[@RileyRampant]

The question I have is, it seems apparent that, to some extent, the elaborations of the lower limbs took place while australopiths were still having a lifestyle involving trees. Does this support the concept that they were developing a terrestrial foraging strategy, and associated adaptations, while maintaining fitness in the trees more or less exclusively with their upper limbs ? That's what the evidence seems to imply - a hybrid arboreal/terrestrial lifestyle - it seems implausible that australopiths, as constituted, would be able to make a living without resort to the protection of trees. An exclusive arboreal lifestyle would not promote the adaptations in evidence. So - some pre-adaptation, with access to terrestrial food sources as selective driver, going back well before autralopithecus, which is somewhat a bipedal 'fait accompli' in progress.

[@philliprobinson7724]

Hi Riley. In the drier regions access to water was even more vital than food. Any mutations to the legs and feet that made for more efficient long-distance travel (between waterholes) would be strongly selected for as permanent adaptations. This explains why we evolved bipedalism before an enlarged cerebral cortex. Lucy was an ape who needed human mobility. I can't imagine a "knuckle-dragging" hominid beating Lucy to the waterhole, even if it had a larger brain. It seems to me the few surviving species of great apes all inhabit rainforests because they didn't need to evolve further, unlike our species. None of the speculations I've read take account of the "dry season" scenario which our ape ancestors must have adapted to long before they had the ability to make water-skins. Our ancestors were still tied to reliable water sources, even after they invented water skins. The idyllic pictures painted by artists show the happy homonims flint-chipping away around a fire near a cave, always with a babbling brook nearby. But you can bet your bottom dollar these sites were ferociously fought over in the dry season as they watched the water level falling. For a laugh, google the Aussie song from mid C20, "A pub with no beer" A case of Deja vu maybe? That's what it must have like for them. "I've tramped fifty flamin' miles, to a pub with no beer". Cheers, P.R.

[@RileyRampant]

@@philliprobinson7724 Beautiful. Great points. Clearly, that magnifies the selection pressures for getting down from the trees more or less daily - also, likely, the need to carry the youngsters along, which also reinforces the need for group cohesion in such hazardous environs, along w/ promoting the hominin/homo walking style. As you say, much of the speculation seems to over-rely upon esp. chimpanzees, when the emergent hominin lifestyle must have been radically different, likely immediately upon the essentially allopatric speciation events associated with the LCA split.. We know vastly less about Chimp evolution, given the unfavorability of fossil formation/preservation in rain-forests, along with a general impression long held that chimpanzees were 'closer' to the root. But the more economical explanation, at this point, is that the late miocene LCA was not a knuckle-walker (Chimps and Gorillas, for example, knuckle walk differently). Would love anyone more informed on these matters to weigh in - i'm just a software guy who has a casual interest in these speculations.

[@philliprobinson7724]

@@RileyRampant Hi Riley. Thanks for that. Did you google the Aussie song? It was sung by "Slim Dusty". Cheers, P.R.

[@philliprobinson7724]

@@nomadpurple6154 Hi Nomad. The "searching for water" theory is consistent with earth's climatic history. Lucy probably evolved during the ice-ages when most of the earth's fresh water was locked in polar ice-caps. Drier climates cause forests to shrink, so our existing tree-climbing adaptations were less important for our survival than new "getting about on the savannah" adaptations. Drier climates would also foster fire use, probably to ward off predators at first. I can't see how we'd have discovered how to make and feed a fire in a dripping wet tropical jungle. It all fits together rather well. "Blast, it's gone out! Sorry dear, there's just no dry wood about in this stinking jungle! Raw snake again tonight is it?" 😅Cheers, P.R.

[@philliprobinson7724]

Hi. And thank you all for dedication to very important work. I would guess that the search for WATER also had a lot to do with evolving bipedalism. Droughts happened everywhere (except the rainforests), and those species able to move hundreds of miles to a new waterhole when their regular pub ran out of beer (sorry, water), would have a huge survival advantage in the drier parts of Africa. Those tied to the trees would go thirsty. I notice the hoofed migrating species are all very efficient travelers. I'd guess bipedalism made us efficient travelers too, and that athletes from Africa usually excel in the Olympic running events. This could be part of their genetic heritage. Cheers, P.R.

[@djlafg58]

A very fine delivery with lots of important information. I was hoping she may have gone on to Ar ramidus, as the picture fills out even more clearly of bipedalism in spite of those ape feet. And of course there are its long ape-like digits. Great for wrapping around branches but no help for bipedalism. Now then how about exploring developments prior to the Australopithicenes and why terrestrial foraging was necessary. Once you start looking for the reasons for bipedalism rather than a quadramanus beast as in the Chimp, then you will be a lot closer to the reasons why bipedalism persisted, despite its drawbacks in the earlier versions as in Ardipithecus and Orrorin. Both were very likely bipedal despite the disadvantages of the early version of 2 footed locomotion. Must have been some powerful facto(s) causing selection for life on 2 feet.

[@freefall9832]

You have to drop everything to climb a tree. They decided to stand their ground and throw rocks and swing clubs. No need for a divergent big toe when you control the situation.

[@MossyMozart]

Thank you, GrandMama Lucy. I wish that I had inherited those gorgeous cheekbones!