an autodidact meets a dilettante…

‘Rise above yourself and grasp the world’ Archimedes – attribution

Archive for the ‘hominins’ Category

a bonobo world? an outlier, but also a possibility: 2

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1. the small world of bonobos

Definitely one of the best introductions to the bonobo world is Frans De Waal’s 2006 essay for Scientific American, available online. It describes a species that branched off from its chimp cousin some two million years ago. Although genetic researchers have made it known that humans are equally related to chimps and bonobos, we’ve come to realise that a basic bean-count of genes shared is an overly simplistic approach to measuring our connectedness with other species. In any case we still have much to learn from both of our closest living relatives, especially in terms of their social relationships, and our own. We have of course developed a culture, or a range of cultures that are much more diverse and dynamic than our primate cousins, which is some cause for optimism. We are, I hope, always learning better how and what to learn.

I believe it is very much worth looking at chimps and bonobos, not as opposites, which of course they aren’t, nor quite as models for humans to follow, but as two of many possible forms of our species in an earlier stage of cultural development. The fact is, and I should think this is unarguable, early humans, in their territoriality, their aggression, their gender-based division of labour, and their ownership fetishism, have largely developed from the basic cultural outlook of chimps rather than bonobos. Our history is marred by mostly male violence and hubris, and the power of possession, formerly of land, latterly of resources and technological know-how, and their transformation into financial power and influence, leading to systemic inequalities and a cult of selfishness.

But of course human culture isn’t one thing, and it has been subject to dizzying developments in modern times. Most astonishing is the growth of knowledge and its availability and rapid dissemination in the internet age. I’ll be taking advantage of that growth and availability in what follows. However the ‘democratisation’ of knowledge that the internet potentially provides is hampered by various anti-democratic forces, such as governments who are largely able, and very much concerned, to control information flow within their borders, and social media moguls who are less interested in accurate knowledge than in the monetisation of any and every opinion. 

Whether the internet revolution, which has been with us for little more than a generation, will lead to a greater homogeneity of human culture, or its opposite, or neither in any clear sense, is yet to be seen, and so it might seem a little rich to try to learn, in our human world of close to 8 billion denizens, from the habits of a small group of primates struggling to eke out an existence in a forested region south of the Congo River. Current estimates of bonobo numbers in the wild range from 10,000 to 50,000. As is well known, their habitat is often under threat due to the political instability in the region, which has also made it difficult to assess numbers. In any case it’s clear, as with most endangered species, that the greatest threat to their survival in the wild is Homo sapiens.

Of course, one way to learn from them is to treat them as just another culture. This no doubt leads to questions about the culture concept, which will be further explored, but it seems clear that the most intelligent non-human species, such as chimps and bonobos, most cetaceans, elephants and some corvids, are highly socially organised, to say the least. Of course, always thinking of counter-examples, I can’t account for the intelligence of octopuses and some other largely solitary cephalopods, though one theory has it that their complex neurology developed as a defence against a wide range of predators – which has also been cited, mutatis mutandis, as an explanation for the complex development of culture in western Europe. 

One of the most interesting questions about bonobos and their largely female-dominated society is how that society came about, considering that bonobo females, like chimps, gorillas and humans, are smaller on average than the males. Clearly, size and attendant strength is an advantage in the kinds of environments early humans and their primate cousins had to deal with. We have no clear answer to this question, though it’s noteworthy that the bonobo diet, being less meat-heavy than that of chimps, would require less aggressive hunting, and strength to overcome prey. This raises the question – did the rise of females lead to a less carnivorous diet or was it the other way around?

First, let’s look at the bonobo diet. They are very much tree-dwellers, and fruit always forms a large part of their diet, but also leaves, seeds and flowers. Animal foods include worms and some insects, and the occasional snake or flying squirrel. This suggests that they rarely go on hunting expeditions. The bonobo habitat is generally more forested than that of chimps, and they spend more time in the tree-tops, harvesting the food they find there. It could be that the physical habitat of chimps, which is relatively more savannah-like, actually led to a more spread-out, competitive culture, compared to the closer-knit bonobos in their denser, tighter environment. If this is true, it’s reasonable to infer that the strength advantage of the larger males might be diminished by habitat. Perhaps, given a few million more years, the size difference between males and females may reduce. 

On another point of physicality, bonobos are described as slightly more gracile, or slender, than chimps, which has led some experts to believe that their physical resemblance to Australopithecus makes them closer to living examples of our direct examples than chimps. Others see different connections:

According to Australian anthropologists Gary Clark and Maciej Henneberg, human ancestors went through a bonobo-like phase featuring reduced aggression and associated anatomical changes, exemplified in Ardipithecus ramidus.

Using bonobos as a guide to potential human behaviour often meets with strong push-back. I’ve experienced this myself in a number of conversations, and usually the argument is that we are so far removed from our primate cousins, and so much more culturally evolved, and diverse, that comparisons are odious. However, I suspect much of this is due to an arrogance about our sophistication which prevents us from learning lessons, not only from other primates but from other cultures that we deem inferior, even without consciously acknowledging the fact. Yet we are learning those lessons, and benefitting from them. Generally speaking, we – I mean those from a WASP perspective, like myself – are recognising that indigenous or first nation cultures were far better adapted to their environments than the later white arrivals – and that this adaptation was hard-won over many generations, during which a collective bank of experience developed. I would cite Bruce Pascoe’s book, Dark Emu, and its many references, for bringing about greater recognition of the achievements of Australia’s long-resident non-European cultures, for example. 

 

References 

https://www.scientificamerican.com/article/bonobo-sex-and-society-2006-06/

https://en.wikipedia.org/wiki/Bonobo

https://www.awf.org/wildlife-conservation/bonobo#:~:text=Total%20bonobo%20population%20numbers%20are,is%20rapidly%20destroying%20the%20rest.

https://www.theatlantic.com/science/archive/2019/07/why-did-octopuses-become-smart/593155/#:~:text=Cephalopods%20do%20not.,that%20chimps%20or%20dolphins%20do.

Dark Emu, by Bruce Pascoe, Magabala Books, 2014

Written by stewart henderson

October 23, 2020 at 3:12 pm

why homo sapiens sapiens?

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Homo sapiens sapiens – really??

Canto: Here’s a question. On the first page of Thomas Crump’s A brief history of science, he mentions our species, Homo sapiens sapiens. I’ve occasionally seen this designation before, but usually we’re only singularly sapient. What gives? I’m not aware of any species called Homo sapiens insapiens or quasisapiens or semisapiens, yet I’m sure there’s a reason…

Jacinta: Well I suspect it’s not because we’re big-noting ourselves, but then again, it is a self-congratulatory moniker, but we deserve it…. don’t we? ‘Sapiens’ being Latin for ‘wise’ or ‘astute’, and we’re doubly so, en it? Anyway, I think it’s about palaeontological techno-lingo, and it’s possibly controversial. Like we’re not the only Homo sapiens species but we’re the only extant ones, and we’re leaving a space open for some earlier Homo sapiens species, either yet to be discovered or yet to be designated as such, instead of being designated as Homo sediba or naledi or whatever.

Canto: So the Australian Museum, which designates us simply as Homo sapiens, does make a distinction between archaic (from 300,000 years ago) and modern (from 160,000 years ago) Homo sapiens, but needless to say, there is controversy, due to the paucity of the record and the mix of archaic and modern features, especially with fossils dated to before 160,000 years ago, which some scientists give an entirely different name, Homo helmei. 

Jacinta: Sounds like the lumpers and splitters issue once again. According to the Bradford foundation, the Homo helmei name is based on one partial skull dating from about 260,000 years ago (aka the Florisbad skull), and claimed (perhaps not by many) to represent an intermediate species between H sapiens and H heidelbergensis. But I suspect some of these scientists want to get recognition for identifying a new species rather than admitting that early humans, like modern ones, came in many shapes and sizes. 

Canto: Well here’s more from the Australian Museum:

Homo sapiens sapiens is the name given to our species if we are considered a sub-species of a larger group. This name is used by those that describe the specimen from Herto, Ethiopia as Homo sapiens idàltu or by those who believed that modern humans and the Neanderthals were members of the same species. (The Neanderthals were called Homo sapiens neanderthalensis in this scheme).

Jacinta: Interesting use of the past tense there. I note that the Australian Museum appears to state unequivocally that modern H sapiens is directly descended from H heidelbergensis. I also note that the Florisbad skull is measured as having a brain capacity larger than the average modern human, but I can’t see how much can be made of that. It’s no doubt still within the range. As for H sapiens idàltu, there’s disagreement, of course. If these 160,000 year-old Ethiopian fossil remains – which include three well-preserved crania, the best of which is of an adult male with again a cranial capacity on the large side – are accepted as a H sapiens sub-species, then this is said to justify the H sapiens sapiens subspecies nomenclature for the rest of us. 

Canto: That’s a partial explanation, but I still think the double sapiens moniker has a hubristic odour to it. Assuming H sapiens idaltu to be a genuine subspecies (such luminaries as the physical anthropologist Chris Stringer disagree), who’s to say it was less sapient than the line that led to us? Just because it didn’t survive? 

Jacinta: Well, that’s the dilemma – if you accept than there are other subspecies, then I suppose you have to accept a triple-barrelled name for each one. The third name – well, we can’t really choose a locality, because we’re everywhere. Or a skill, because we have too many. The name idaltu, by the way, comes from the Afar language around Ethiopia, and means ‘elder’ or ‘first-born’, which seems to suggest that this subspecies was ancestral to ours. In any case, you could argue that since our species basically controls the Earth, as mistresses of all we survey, the double sapiens title is well-earned. At least until we get zapped off our pedestal by multiply sapient aliens. 

Canto: Yeah, well, one sapiens is enough for me, and I’m sticking with that. 

 

References 

https://australian.museum/learn/science/human-evolution/homo-sapiens-modern-humans/#:~:text=Homo%20sapiens%20sapiens%20is%20the,members%20of%20the%20same%20species.

https://en.wikipedia.org/wiki/Florisbad_Skull

http://www.bradshawfoundation.com/origins/homo_helmei.php

https://en.wikipedia.org/wiki/Homo_sapiens_idaltu

Written by stewart henderson

September 27, 2020 at 6:36 pm

Human ancestry 2 – a meander through a couple of million years’ time and a world of space

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Man is descended from a hairy, tailed quadruped, probably arboreal in its habits.

Charles Darwin

Homo neanderthalensis, with a very bad toothache

 

So in this second post I’ll take a little look at Paranthropus and then try to make sense of the move from Australopithecus whateva to Homo whateva, and so on….

There’s a lovely vid about Paranthropus here, which I’ll take much of the following from. There are three known species, P aethiopicus (about 2.7 to 2.3 mya), P boisei (2.3 to 1.4 mya), both only found so far in eastern Africa, and P robustus (2 to 1.2 mya), in southern Africa. They’re all robust species, as opposed to the gracile species A africanus. They have large cheekbones, jaws and teeth, and a prominent sagittal crest across the top of the cranium, a feature shared by gorillas and orang-utangs, and which evolved to attach strong chewing muscles down to the jaw. Apart from these robust characteristics, they shared many features with australopithecines, and have even been defined as robust australopithecines by some. It’s always difficult to split up (or lump together) specimens when only small fragments are found, so there’s a hunt on for more, and bigger, bits and pieces. From what they’ve got, though, it’s estimated that they had a cranial capacity of 475-545 cc, not much more than the average chimp, with a height of about 156cm (just over 5 feet) and a weight of 40-50kg. Smallish perhaps, but I’d be willing to bet they had a pretty impressive muscle to fat ratio. They also appear to have been sexually dimorphic to a greater degree than humans, suggestive of dominant males fighting over females, as in the case of gorillas. There’s also some evidence that the females lacked or had a less prominent sagittal crest. 

How are the Paranthropus species related to modern humans? Surprise surprise, we don’t know, and the pathways to and between the various types of Homo just get more complicated. They may simply have died out, as the more recent Neanderthals did. Researchers desperately await more finds, and more techniques for connecting the dots. 

So, leaving Paranthropus behind, it’s clear from my last post on the subject that tracing the path from our common ancestor with bonobos (my fave ape) has been a fraught process of speculation and disputation, but of course we have no choice but to keep on trying to trace that path. So, what’s the most recently-lived species of Australopithecus, and the most ancient of the Homo species, as far as we know? 

The species A africanus and A sediba seem currently to be in competition to be the immediate ancestor to Homo habilis along the pathway to H sapiens, though there may have been an intermediate, as yet undiscovered, species.

A africanus is known from four sites, all in South Africa, but dating the specimens has been difficult and controversial. The first discovery, the Taung child (1925) is still not clearly dated, and claims for it suffered at the time of its discovery, and for decades afterwards, due to the Piltdown hoax, which I won’t go into here. However, in the mid 1930s the first adult australopithecine was found, and eventually given the A africanus moniker. Evidence of bipedality in this and another adult female, found in 1947, together with evidence of a cranial capacity of about 485 cc for both, was striking evidence that bipedality long preceded brain growth (it has since been mooted as a result of reduced forestation and increased savannah-like environments through climate change, though bipedal traits seem to have existed even before this). A lack of facial projection in these specimens was suggestive of advancement towards modern humanity. And just by the bye, evidence of tool-making among hominins now goes back to 3.4 mya, associated with the A afarensis species. A fourth specimen, ‘Little Foot’, dated to around 3.7 mya, was found in the nineties, but there’s debate about whether it belongs to A africanus or a ‘new’ species, A prometheus (actually suggested by Raymond Dart decades ago). There’s an interesting piece on this here.

I wouldn’t want to be quoted on this, but it seems that the A africanus fossil of a skull now known as ‘Mrs. Ples’ is the most recent A africanus fossil ever found, dated to about 2mya. But what about A sediba? This is the most recently discovered australopithecene, mostly associated with Lee Berger (and his young son), who discovered the first bones in 2008, in South Africa. It has been argued, by its discoverers, to be the most likely transitional species between A africanus and either Homo habilis or H erectus (and it should be noted that many consider H (or A) habilis to be an australopithecine, its placement as Homo being largely based on the use of flaked stone tools, at a time when tool use by australopithecines wasn’t known).

So I think I’ll skip this controversy for now, as I want to get to the more recent radiation of Homo species. Having said that, immediately I start looking at the earliest forms given the Homo moniker, such as H habilis, H erectus and H ergaster, I encounter vast uncertainty and controversy, not to mention my own ignorance. I’ve already discussed H habilis; H ergaster (1.9 to 1.4 mya), according to Wikipedia, ‘is now mostly considered either an early form, or an African variety, of H erectus‘. Oh dear, I thought H erectus was African!

In fact, the first fossils identified with H erectus were found in Eurasian Georgia and in China, but the species may have back-migrated to Africa. Or maybe not. I’m on the verge of giving up here, but I’ll extricate myself from the mess by listing and briefly discussing the various forms of Homo that have been postulated. These aren’t necessarily in chronological order.

  1. H habilis (approx 2.1-1.5mya) – short but with longer arms compared to modern humans, with a cranial capacity of around 700 cc. Used stone tools. Relatively robust, compared to H ergaster. Contested classification. Probably co-existed with H erectus. Only found in Africa.
  2. H ergaster (approx 1.9-1.4mya) – I’ve used the Wikipedia existence range here, but the Australian museum suggests that arguments about existing classification of specimens may extend that range up to 700,000 ya. They also point out that some don’t accept this classification at all, preferring H erectus. They were relatively hairless and more closely resembled modern humans than earlier types. Possible specimens found in modern Kenya, Ethiopia, South Africa, and most notably in Georgia (Eurasia), which suggests first emergence of early humans from Africa occurred about 1.7mya. Cranial capacity, about 860cc .
  3. H erectus (approx 1.8mya- 100,000ya?) – first found in Java, other specimens found in Indonesia, China and Africa. Short and stocky with heavy brow ridges. Sometimes hard to separate from H ergaster, especially the African specimens. H erectus is now more widely believed to be a side-branch, and H ergaster our more direct, if more ancient, ancestor. Cranial capacity about 1050cc.
  4. H rudolfensis (approx 2.4mya- 1.8mya) – specimens found in modern Malawi and Kenya. A contested classification, could be lumped in with H habilis. There is always a difficulty when dealing with limited specimens, which might be atypical, juvenile or of unknown gender. Anyway, estimated cranial capacity, about 750cc. Size and shape insufficiently known.
  5. H heidelbergensis (c700,000-300,000 ya) – evolved in Africa, but in Europe by 500,000 ya (African fossils are mostly older). Lived and worked in co-operative groups, using a variety of tools. Specimens found in England, France and Spain as well as in the region of Heidelberg, Germany. Possibly as far east as northern India. Also in Zambia and South Africa. Physically tall, up to 180 cms, suggesting descent from H ergaster. Brain capacity approx 1250cc.
  6. H neanderthalensis (?800,000-40,000 ya) – some have argued that they were around as recently as 28,000 years ago. The first fossil was found in the 1820s, and was the first fossil of any extinct hominin ever found. Their cranial capacity, at 1500cc, is larger than that of H sapiens, not surprisingly due to their larger overall build (shorter but much more solid). No specimens found as yet in Africa, but a large number of finds throughout Europe and the Middle East (and possibly in China) allow us to build a clearer picture of Neanderthals than any other extinct hominin. They used a variety of tools, which they may have obtained through trade with modern humans. They wore animal hides and used fire for warmth, cooking and protection. Physically they were thickset, with heavy brow ridges and a relatively receding forehead, a forward-projecting face, a large, broad nose, and strong neck muscles. It’s now known, of course, that they interbred to some degree with modern humans, but it’s also likely that they competed with them for scarce resources, especially during ice ages. Though we don’t now consider them to be ‘nasty, brutish and short’ it may well be that the greater resourcefulness of H sapiens hastened their demise.
  7. H rhodesiensis (c800,000-120,000 ya) – now generally seen as an African subspecies of H heidelbergensis, with specimens found in Rhodesia/Zambia, Ethiopia and Tanzania.
  8. H cepranensis (c900,000-800,000 ya) – based on one fossil skull cap, or calvaria, unearthed near Ceprano, Italy in 1994. Others are for H heidelbergensis. The dating is also highly contested, with some arguing for around 450,000 ya. There’s probably quite a few more of this sort – but every new find is exciting.
  9. H denisova (? – 15,000 ya) – This isn’t an agreed taxonomic title, but the Denisovan finds are certainly exciting, with mitochondrial DNA being recovered from the first find (in a Siberian cave), the finger-bone of a juvenile female (how do they know that??). Other specimens have been found in the same cave, and another has been found in Tibet. There’s not enough material for us to picture this species, but the DNA tells us that they interbred with Neanderthals, and to a lesser degree with Melanesians, Papuans and Aboriginal Australians.
  10. H floresiensis (c190,000-50,000 ya) – found only on the Indonesian island of Flores. Another exciting, and puzzling, recent find. Could they have been killed off by those passing though on their way to Australia? Researchers are still hoping to recover mitochondrial DNA from the most recent specimens. Physically, these were unique humans with a very small stature and a cranial capacity of 380cc (chimp size), though with an enlarged Broadman area 10, which is associated with complex cognitive abilities. Other skull features, though, suggest a primitiveness going back more to H erectus. Tools found at the site have raised controversy. Do they belong to H floresiensis? They don’t easily equate with such a small brain. There is no precedent. Much still to be learned.

So I’ve raised far more questions for myself than I’ve answered. Hope to come back to this topic in future, with a focus on bipedality, climate effects, the beginnings of ‘culture’, and migration, among other things.

References

https://australianmuseum.net.au/learn/science/human-evolution/ (a great site, with links to details on particular species)

Paranthropus evolution (video), by Stefan Milo, 2019

https://en.wikipedia.org/wiki/Australopithecus

https://en.wikipedia.org/wiki/Australopithecus_africanus

https://en.wikipedia.org/wiki/Australopithecus_sediba

https://en.wikipedia.org/wiki/Homo_ergaster

http://humanorigins.si.edu/evidence/human-fossils/species/homo-habilis

Written by stewart henderson

October 30, 2019 at 9:59 pm