an autodidact meets a dilettante…

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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

stuff on human ancestry 1: the australopithecines, mostly

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All the evolution we know of proceeds from the vague to the definite

C S Pierce

some of these depictions are more vague than others – we’re definitely not there yet

 

I was in a bookshop yesterday, where I picked up a copy of Yuval Noah Harari’s book Sapiens and had a gander at the back cover. I read one sentence, which went something like ‘100,000 years ago there were at least six species of Homo sapiens, now there is only one.’ Or maybe it was just ‘six species of Homo‘. It resonated with me, because it’s been a while since I’ve researched and written about the ever-fascinating topic of human origins, a topic that resurfaced for me recently on reading an essay, ‘Lucy on the earth in stasis’ by Stephen Jay Gould in his 1996 collection Dinosaur in a haystack. The essay promoted his ‘punctuated equilibrium’ view of evolution, as it reported that Australopithecus afarensis appeared to be the only hominin type in existence for a period of almost a million years, from approximately 4.9 million years ago to 4 million years ago, after which there was a relatively rapid radiation of hominid species. I could only take the essay on trust, but I maintained the thought that I should investigate whether this claim still held, some twenty-three years later. And that, further, I should investigate whether we were any clearer about our descent, as the last surviving species of that apparent radiation.

And by the way, for my education’s sake I need to straighten out the difference between hominids and hominins. We humans are both, apparently. The hominids, or great apes, include four genera: Pongo, the orang-utangs, of which there are three extant species; Pan, of which there are two species, chimps and bonobos; Gorilla (two species), and Homo, of which there’s only one extant species, but many extinct ones including Neanderthals. The term ‘hominid’ has broadened over time. The term ‘hominin’ is more restrictive, referring only to those species ancestral or related to humans, since the split from the chimp and bonobo line. This explains, I hope, why we are both hominids and hominins. Clearly, though, I should stick to the term hominin for this post, or series of posts.

Anyway, I was surprised to read this claim about the state of human play 100,000 years ago. The old Bill Bryson question, How do they know that? came to mind, but I also felt skeptical, as I seemed to remember that the number was smaller – possibly dependent on whether you were a lumper or a splitter.

We know of course that our closest living relatives are (equally) chimps and bonobos, and the latest dating of our divergence from their line is 4 to 7 million years (according to Wikipedia, but Gould put it at 6 to 8 mya, and this video from the American Museum of Natural History gives it more ‘precisely’ at 7 mya, and another Wikipedia article gives the figure as 6.5 to 5.5 mya, so who knows?) There are a couple of possibilities for our last shared ancestor – Sahelanthropus tchadensis and Orrorin tugenensis – but their more or less competing claims are mired in uncertainty, due to the extreme sparsity of material. It may well be that neither of them fit the bill.

When they look at the evidence from early hominins, researchers are particularly interested in signs of bipedalism, which have been argued to exist in S tchadensis due to the placement of its foramen magnum (the hole in the skull through which the spinal cord passes) towards the back – though this placement has been disputed, quelle surprise. In any case, these earliest hominins evolved during the Pleiocene epoch into the definitely bipedal australopithecines. The bipedal adaptation is so important to the emergence of Homo sapiens that it has been the subject of a great deal of speculation, hypothesis and argumentation. It’s likely that there were a variety of converging factors that favoured this trait’s development. For example, it provided a wider visual field, especially on the ground; it left the hands free to grasp and carry food; it enabled long-distance running, and it reduced the expenditure of energy. However, bipedalism appears to have been a slow development, and early australopithecines such as A afarensis likely spent a lot of time in trees. This is supported by anatomical features such as longer arm-bones, curved fingers, a shallow rib-cage and strong clavicular anchors for brachiation (swinging from the arms among branches).

Over time there were anatomical changes favouring bipedality. These included greater robustness of the ankle and knee joints, and changed positioning of the foramen magnum, the femur and the spine, to support changes to the centre of gravity. But the changes which have had the most long-lasting, even at times dire effects, have been those to the pelvic region. The strengthening and widening of this region, including the ilium, ischium and pubis, to support an upright stance, has to a serious degree compromised the process of childbirth. It’s been observed that australopithecines share with modern humans a sexual dimorphism relating to the lumbar vertebrae, allowing the spinal curvature of females to become more pronounced during pregnancy, which helps to better distribute the weight of the unborn child and to reduce fatigue and maintain stability of posture for the mother. However, the changed shape of the pelvis and the consequent narrowing of the birth canal resulted in what has become known as ‘the obstetrical dilemma’. Unlike virtually every other mammalian species, humans face major difficulties and dangers in childbirth, which require others – midwives or other medical professionals – to assist in the process (for example, neonatal rotation is often necessary for safe delivery). A ‘solution’ to this dilemma, which appears to have evolved over time, is a comparatively short gestation period – the time spent in the womb – to give a greater opportunity for both mother and child to survive the birth. This of course leads to a longer period of childhood dependence as it develops outside the womb. Apparently, a modern human baby is born with approximately 25% of full brain development, compared to 45-50% in other primates. Brain size at birth is limited due to the obstetric dilemma, and greater neoteny is the result. 

Encephalisation, which refers to a growth in brain size or mass relative to body size, is now seen as a later development in the human story than bipedalism. Brain size in general has become very questionable as a measure of complex evolutionary development – witness those smart corvids – and it’s worth noting that the Neanderthal brain is on average larger than ours. What’s important, though, is brain structure – something we can’t really look at vis-a-vis our ancestors. However it is reasonable to assume that our much larger brain size compared to australopithecines is largely due to growth in the temporal lobes and the prefrontal cortex. In fact all regions have grown, including the cerebellum, traditionally associated with fine motor control and balance, but more recently connected with cognitive function and language.  

But let me return to the hunt for the hominin links from the other great apes to Homo sapiens. In the mid-nineties, two new examples of early hominins were discovered, Australopithicus anamensis and Ardipithecus ramidus. I’m guessing that Gould didn’t know about these discoveries when he wrote his essay, as they seem to have punctured his punctuated equilibrium thesis, at least as regards hominins. Anyway the anamensis species is believed to have lived from about 4.2 to 3.8 million years ago, and the A ramidus specimens have been dated to around 4.4 million years ago, but interestingly, A afarensis, the principal subject of Gould’s essay, is now believed to have lived from 3.9 million years ago to 2.9 million years ago – that’s a million years after Gould’s stated range. The australopithecines first came to our attention in 1925 when Raymond Dart described Australopithecus africanus from specimens found in South Africa. A africanus is a more gracile type, and may well be in the direct line to humans, though there’s been a lot of dispute about the dating and classifying of different specimens. A africanus is generally thought to be a more recent species than A afarensis, another gracile type. So maybe we can link A africanus back to A afarensis, which in turn can be linked back to S tchadensis, with some intermediate missing links. But then there’s another recently discovered species, Australopithecus sediba, which has been dated to around 2 million years ago and is thought to be a transitional species between A africanus and either Homo habilis (which some prefer to describe as Australopithecus habilis) or Homo erectus. Another gracile species discovered in the nineties, A garhi, dating to about 2.5 million years ago, also seems to fit as a species connecting Australopithecus and Homo. From what I’m reading, the fragmentary nature of these finds, together with obvious questions as to whether particular specimens are typical of whole species (type specimens are often juveniles, which might not be such a good idea), are the main barriers to pinning down the precise lines of succession. That’s why every new discovery is such a treasure. 

I haven’t mentioned Ardipithecus or Paranthropus as yet. In the nineties specimens were found in the Afar triangle in East Africa, and classified as Ardipithecus ramidus (around 4.4 million years ago, with uncertain evidence of bipedality, and some evidence of reduced sexual dimorphism) and Ardipithecus kadabba (about 5.6 mya, possibly an ancestor of A ramidus, but known from only a few teeth and bones – the type specimen being a bit of mandible with an attached molar). It’s possible, according to some researchers, that Ardipithecus, Orrorin, and Sahelanthropus all belong to the same genus. 

I’ll have a look at Paranthropus, apparently a more robust distant cousin of ours, then move forward to the Homo genus, next time. 

References

Australopithecus Evolution (video), by Henry the PaleoGuy, 2019

Seven million years of human evolution (video), American Museum of Natural History, 2018

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

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

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

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

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

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

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

http://humanorigins.si.edu/evidence/human-fossils/species/ardipithecus-ramidus

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

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

Written by stewart henderson

October 23, 2019 at 5:16 pm

When was the first language? When was the first human?

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Reading a new book of mine, Steven Pinker’s The sense of style, 2014, I was bemused by his casual remark on the first page of the first chapter, ‘The spoken word is older than our species…’. Hmmm. As Bill Bryson put it in A short history of nearly everything, ‘How do they know that?’. And maybe I should dispense with ‘they’ here – how does Pinker know that? My previous shallow research has told me that nobody knows when the first full-fledged language was spoken. Furthermore, we’re not sure about the first full-fledged human either. Was it mitochondrial Eve? But what about her mum? And her mum’s great-grandad? Which raises an old conundrum, one that very much exercised Darwin, and which creationists today love to make much of, the conundrum of speciation.

Recently, palaeontologists discovered human-like remains that might be 300,000 years old in a Moroccan cave. Or, that’s the story as I first heard it. Turns out they were discovered decades ago and dated at about 40,000 years, though some of their features didn’t match with that age. They’ve been reanalysed using thermoluminescense dating, a complicated technique involving measuring light emitted from escaping electrons (don’t ask). No doubt the dating findings will be disputed, as well as findings about just how human these early humans – about 100,000 years earlier than the usual Ethiopian suspects – really are. It’s another version of the lumpers/splitters debate, I suspect. It’s generally recognised that the Moroccan specimens have smaller brains than those from Ethiopia, but it’s not necessarily the case that they’re direct ancestors, proof that there was a rapid brain expansion in the intervening period.

Still there’s no doubt that the Moroccan finding, if it holds up, is significant, as at the very least it pushes back findings on the middle Stone Age, when the making of stone blades began, according to Ian Tattersall, the curator emeritus of human origins at the American Museum of Natural History. But as to tracing our ancestry back to ‘the first humans’, we just can’t do this at present, we can’t join the dots because we have far too few dots to join. It’s a question whether we’ll ever have enough. Evolution isn’t just gradual, it’s divergent, bushy. Where does Homo naledi, dated to around 250,000 years ago, fit into the picture? What about the Denisovans?

Meanwhile, new research and technologies continue to complicate the picture of humans and their ancestors. It’s been generally accepted that the last common ancestor of chimps and humans lived between 5 and 7 million years ago in Africa, but a multinational team of researchers has cast doubt on the assumption of African origin. The research focused on dental structures in two specimens of the fossil hominid Graecopithecus freybergi, found in Greece and Bulgaria. They found that the roots of their premolars were partially fused, making them similar to those of the human lineage, from Ardepithecus and Australopithecus to modern humans. These fossils date to around 7.2 million years ago. It’s conjectured that the possible placing of the divergence further north than has previously been hypothesised has much to do with environmental factors of the time. So, okay, African conditions were more northerly in those days…

So these new findings and new dating techniques are adding to the picture without clarifying it much, as yet. They’re like tiny pieces in a massive jigsaw puzzle, gradually accumulating, sometimes shifted to places of better fit, and so tantalisingly offering new perspectives on what the whole history might look like. I can imagine that in this field, as in so many others, researchers are chafing against their own mortality, as they yearn for a clearer, more comprehensive future view.

Meanwhile, speculations continue. Colin Barras offers his own in a recent New Scientist article, in which he considers the spread of H sapiens in relation to H naledi and H floresiensis. The 1800 or so H naledi fossil bones, discovered in a South African cave four years ago by a team of researchers led by Lee Berger, took a while to be reliably dated to around 250,000 years (give or take some 50,000), just a bit earlier than the most reliably dated H sapiens (though that may change). Getting at a precise age for fossils is often difficult and depends on many variables, in particular the surrounding rock or sediment, and many researchers were opting for a much earlier period on the evidence of the specimens themselves – their small brain size, their curved fingers and other formations. But if the most recent dating figure is correct (and there’s still some doubt) then, according to Barras, it just might be that H sapiens co-existed, in time and place, with these more primitive hominids, and outcompeted them. And more recent dating of H floresiensis, those isolated (so far as we currently know) hominids from the Indonesian island of Flores, has ruled out that they lived less than 50,000 years ago, so their extinction, again, may have coincided with the spread of all-conquering H sapiens. Their remote island location may explain their survival into relatively recent times, but their ancestry is very much in dispute. A recent, apparently comprehensive analysis may have solved the mystery however. It suggests H floresiensis descended from an undiscovered ancestor that left Africa over 2 million years ago. Those who stayed put evolved into H habilis, the first tool makers. Those who left may have reached the Flores region more than 700,000 years ago. The analysis is based on detailed comparisons with many other hominid species and earlier ancestors.

I doubt there will ever be agreement on the first humans, or a very precise date. We’re not so easily defined. But what about the first language? Is it confined to our species?

Much of the speculation on this question focuses on our Neanderthal cousins as the most likely candidates. Researchers have examined the Neanderthal throat structure as far as possible (soft tissue doesn’t fossilise, which is a problem), and have found one intriguing piece of evidence that makes Neanderthal speech plausible. The semi-circular hyoid bone is located high in the human throat, and is found in the same place in the Neanderthal throat. Given that this bone is differently placed in the throat of our common ancestors, this appears to be an example of convergent evolution. We don’t know the precise role of the hyoid in speech, but it certainly affects the space of the throat, and its flexible relationship to other bones and signs of its ‘intense and constant activity’ are suggestive of a role in language. Examination of the hyoids of other hominids suggests that a rudimentary form of language may go back at least 500,000 years, but this is far from confirmed. It’s probable that language underwent a more rapid development between 75,000 and 50,000 years ago. It’s also worth noting that a full-fledged language doesn’t depend on speech, as signing proves. It may be that a more or less sophisticated gestural system preceded spoken language.

a selection of primate hyoid bones

Of course there’s an awful lot more to say on the origin of language, even if much of it’s highly speculative. I plan to watch all the best videos and online lectures on the subject, and I’ll post about it again soon.

References

https://www.sciencedaily.com/releases/2017/05/170523083548.htm

https://www.vox.com/science-and-health/2017/6/7/15745714/nature-homo-sapien-remains-jebel-irhoud

Did Neanderthals Speak?

http://www.isciencetimes.com/articles/6557/20131220/neanderthals-speak-like-humans-hyoid-bone-study.htm

https://www.newscientist.com/article/2128483-mystery-human-hobbit-ancestor-may-have-been-first-out-of-africa/

https://www.newscientist.com/article/2128834-homo-naledi-is-only-250000-years-old-heres-why-that-matters/

Written by stewart henderson

July 9, 2017 at 11:14 am