Archive for the ‘anthropology’ Category
the graeco-roman world: a brief reflection
Because I haven’t written much here in a while, methinks I should throw something down. I have a few things in the pipeline, but regular bouts of mild depression and sapped confidence, the is-it-really-worth-it phenomenon that overwhelms me from time to time, have left things in abeyance. So I’ll just say that I’ve finished reading a book. The Classical World by Robin Lane Fox was a cheapie, in the classical orange Penguin series. It’s the fourth book by Fox that I’ve read in the last year or two, and obviously discovering his work has been one of the great delights for me in recent times. I’ve been fascinated by the Graeco-Roman world since I was a teenager, and to find a ‘companion’ to help me explore and re-explore that world, a companion who’s liberal, sceptical, insightful, thorough and deeply fascinated by every aspect of human activity, almost makes up for not being able to be there. And by ‘there’ I mean in the Graeco-Roman world itself, but also in modern Europe and the Middle East, amongst the ruins and the archaeological digs, breathing in the traces of ancestors.
Fox ends this book at the reign of Hadrian, one of the wiser emperors, who chose to abandon the interminable military campaigns of his predecessors and to consolidate an almost unimaginably vast empire by travelling through it constantly and making himself relatively accessible to the ‘plebs’. One could argue that this was the high point of empire, from which the decline was so gradual as to be imperceptible to any ‘groundling’, just as we struggle today to work out whether certain superpowers – the term ’empire’ being hopelessly old-fashioned and discredited – are on their way up or down, and at what rate. The difference being that in today’s less rigidly confined and more informed western society, analysis of these issues is available to just about everyone at the click of a mouse.
Comparisons, though, are never as easy as they seem, because one of the first things you learn on examining the Graeco-Roman world in more detail is that it was never monolithic, in space or time. Of course we can generalize about a lot. Apart from the huge growth of the modern press, there is modern science and the concept of human rights. While slavery persists almost everywhere, it’s no longer sanctioned anywhere. Democracy, occasionally experimented with in the classical world, is a modern western standard, as is basic education for all. But many of these developments which we take for granted are relatively recent, and a historical glance at the Europe of only a few hundred years ago – the Europe of the thirty years’ war in the first half of the seventeenth century for example – might well have us preferring even the life of a slave in the Rome of Hadrian’s time.
This brings me to the old question of the impact of Christianity and the development of Christendom. Fox’s book ends on this ambiguous note, with Hadrian in his ‘semi-retirement’ villa:
By his judgements, his letters and his edicts, it was Hadrian who now made the laws by which justice was done. As emperor, he was freed from the laws; as an educated man, he was personally free from fears of the underworld. Nonetheless, in a famous poem, he addressed consolatory words to his ‘little soul’, a future wanderer in a chilly and humourless afterlife. Long centuries of change in the scope of justice, freedom and luxury lay behind Hadrian’s outlook from his villa garden. But he had no idea that the Christians, whose harassment he regulated, would then overturn this world by antiquity’s greatest realignment of freedom and justice: the ‘underworld’ would no longer be a garden-designer’s fancy.
Actually, not so ambiguous perhaps. The underworld, the pagan version of the Christian Hell, was a desolate, if rather ‘iffy’ sort of place. The Hell that replaced this nebulous, half-fancied world was definite, inescapable and relentlessly horrific. And it was apparently controlled and manipulated by the authorities of this world. A dark age indeed.
the Veblen effect and other psychological tricks
piously good stuff
A very interesting piece of research on violins and their quality, presented here, brings to mind various effects which influence our judgement when we buy or consume something.
I’ve often heard it said that you can’t beat a Stradivari or a Guerneri violin for sound quality and ‘character’, and generally the people saying it are virtuoso violinists, so I would have little hesitation in deferring to their judgement, though I would naturally want some evidence about what makes these older violins better, and why these features can’t be reproduced by modern violin makers. And even though I would readily concede that others have a better ear for quality sound and quality music than myself, terms such as ‘depth’ or ‘richness’ of sound or timbre do have rather a ring of subjectivity to them.
The double-blind research essentially found that even expert musicians and musicologists couldn’t distinguish a Stradivari from a modern instrument. The comments on the above-mentioned piece, including comments from one of the people who conducted the research, are for the most part quite enlightening, but there’s a lot of special pleading which tries to dismiss or downplay the essential finding – which is, that claims about these early violins being superior to anything made since are simply bogus. This finding can also be applied to other musical instruments [guitars being a favourite among the commentariat], as well as wines, cheeses and other products people like to get sniffy about. These non-evidence based preferences are largely a product of the Veblen effect. The prestige associated with eating, drinking, owning or playing an expensive big-name item tricks you into believing it tastes or sounds better than something cheaper or less well-known. The same effect, essentially, accounts for the general claim that ‘organic’ food tastes better than non-organic food. To those inclined that way, organic food has a prestige, a cachet, which other foods don’t possess, and this will ‘trick’ them into swearing that they can taste a real difference when they know, or think, they’re eating something organic.
With organic food there’s also the halo effect to worry about – that’s when you believe that because you’re eating something that is good for you, you can taste that goodness [the nutritious goodness being sort of enriched by moral goodness]. For example, in one little experiment, when subjects were offerred sandwiches and other foods labelled organic and those labelled as not organic, they almost universally preferred the flavour of the organically labelled products. There was in fact no difference between the two.
Will we ever be able to answer definitively this question about the supposedly superior flavour of organic food? I very much doubt it. We might like to imagine that, though taste is subjective, flavour is a matter of chemistry and can be scientifically analysed, but that doesn’t mean people will agree on flavours other than in the broadest terms. Where the differences are minute, as they generally are with organics, and with many wines, cheeses, olive oils, etc, we’ll never come to an agreement, and psychological effects such as the Veblen effect and the halo effect will continue to play a big role. Still, the more educated we are about these effects, the better.
ancient cultures and technologies
The book I’ve been reading on the neanderthals [the convention is to use capitals for these people, but I’m not sure about this, as we don’t use capitals for humans – and clearly neanderthals are a type of human, and we don’t use capitals for dolphins, lions and chimpanzees, so…] has made me think so discursively, and has opened up so many areas in which I’m ignorant and would like to learn more, that it’s hard to know where to begin. One area is that of ancient, ancestral or proto-human technologies. That’s to say, the tools these peoples used, to hunt and to gather mostly, and any other implements or pieces they might fashion. Terms such as Aurignacian, Mousterian, Gravettian and Châtelperronian are used in the book, and I’ve only vaguely heard of the first one, so I’m going to write a post here to educate myself.
It would nice to be able to neatly associate each of these cultural and technological designations with particular times and places and stages of human development, but as always, things are much more complicated. Anyway, I’ll take each of them in turn.
aurignacian tools
The name Aurignacian comes from the ‘type site’ in Aurignac in south-west France, near the Spanish border. The culture is currently dated from 47.000 to 41,000 years ago, though artifacts of Aurignacian type, such as the Venus of Hohle Fels, are continually being discovered and analysed, leading to re-appraisal of both the period and the cultural content. Aurignacian cultural sites are spread throughout southern Europe, from the western Iberian peninsula to the Crimea. Their flint tools were blades and bladelets made from a prepared lithic core, rather than flakes typical of Acheulean and Mousterian culture.
mousterian tools
Mousterian culture is named from the type site of Le Moustier in Aquitaine, France. It’s generally associated with the neanderthals, though it has also been associated with anatomically modern humans in north Africa and the eastern borders of Europe. Not surprisingly its period coincides with the neanderthal period – between 300,000 and 30,000 years ago. It’s associated with flint flake tools, and no art-work or decorative elements have so far been connected with it. The tools are sometimes associated with more sophisticated techniques such as Levallois.
gravettian tools
The type site of La Gravette, also in France, in the Dordogne region, gives its name to the Gravettian culture, noted for the use of small pointed blades in hunting larger game, such as mammoths, bison and reindeer. They also used nets for hunting. Dated between 28,000 and 23,000 years ago, it succeeded Aurignacian culture, with a similar creation of Venus figurines. The culture is divided into two regional groups, one around France, the other in the central European plains and Russia. One important feature of their technology was the use of a tool known as a burin for carving and engraving.
chatelperronian tools
Châtelperronian industry, another French designation, is associated with central and south-western France and northern Spain [the above pic is from J L Katzman’s website on paleolithic and neolithic artefacts]. It’s apparently difficult to distinguish from Gravettian and is often lumped together with it under the name of Perigordian. It has been controversially associated with neanderthals, because of claimed development upon Mousterian techniques of tool-making. It’s generally dated between 35,000 and 29,000 years ago. The direct connection between this type of technology and particular types of proto-humans is a notoriously vexed question.
There are other ancestral technologies and cultures worth mentioning. The Uluzzian of southern Italy and the Szeletian of eastern Europe [along with the Châtelperronian] were once claimed as ‘transitional’ post-Mousterian types indicative of neanderthal acculturation from Arignacian Homo sapiens, but this has been increasingly disputed. The many complex issues involved are way beyond my capacity to explain, but this paper provides a comprehensive account. The conclusion, along with Finlayson’s observations on the effects of microclimates and particular regional ecologies and the modifications of technology and hunting strategy they bring about, raise useful questions about acculturation, transitions and the realities of the multi-faceted middle-upper paleolithic period.
australopithecus sediba
I’ve been writing a bit about the origins of Homo sapiens, for example here and here, but I’ve said virtually nothing about Australopithecus sediba, a species, sub-species or whatever which has been much in the anthropological news of late. Having read up a little on the matter, I don’t know quite where to start.
Well, I’ll start with Steven Novella’s treatment of the recent findings on SGU. He makes the point that we have so little to go on as yet that we can’t be sure, but the evidence so far presented suggests that we may have found the species from the Australopithecus genus that connects it to the Homo genus. The finds were made in 2008 and have been written up recently. As Novella points out, what we’re looking for is the first evidence, in otherwise ‘primitive’ specimens such as australopithecines, of features, or some kind of feature at least, that’s typical of more modern forms, forms in the Homo line. It’s very shaky stuff because of the paucity of material from which to make generalisations, but there seems to be some tentative evidence that these specimens, possibly a mother and son, are the most human-like australopithecines yet discovered. They’ve been dated quite precisely now, to a little under 2 million years of age. Homo erectus is currently dated as existing between 1.8 and 1.3 mya. The African Homo ergaster – which has in recent years become more accepted as a distinct species, is believed to have evolved from the earlier Homo habilis around 1.9 to 1.8 mya, or to have diverged from it, with the two sharing a common ancestor. The most recent fossil attributed to H ergaster is about 1.4 million years old, and the evidence indicates that H habilis and H ergaster co-existed for a few hundred thousand years.
The matter is quite complicated, made more so by recent finds. Up until last year H habilis was the earliest known species of Homo, but analysis of some fossil remains found back in the seventies, using various recently developed techniques, have uncovered [not incontestably I’m sure] a new, more ancient species, H gautengensis. Interestingly, those making claims for H gautengensis argue that because it is older than the Australopithecus sediba specimens found, and because it appears to be larger brained and more ‘advanced’ generally than A sediba, this casts severe doubt on claims for A sediba being the transitional species. They suggest that A garhi, a gracile australopithecine, fossils of which date back to 2.5 mya, is a more likely candidate.
What’s fascinating about all this paleo-anthropological activity and controversy is the development of research tools which seems to allow more and more legitimate inferences to be drawn from less and less material. Take this quote from The Guardian on the research done on A sediba:
Researchers used a powerful x-ray scanner at the European Synchrotron Facility in Grenoble, France, to create exquisitely detailed maps of the interior of the skull of one of the individuals. The bumps and other contours revealed the imprint of a small brain, only 420 cubic centimetres in volume, but one that was apparently reorganising from a primitive structure into a more modern form.
Kristian Carlson, a colleague of Berger’s who worked on the brain scans, said some areas of the organ appeared more developed than expected.
“There are areas above and behind the eyes that are expanded and they are responsible for multitasking, reasoning and long-term planning. These are changes that mirror the differences that humans exhibit from chimpanzees,” Carlson said. The discovery challenges the previously held theory that our ancient ancestors grew large brains before they reorganised to resemble the modern human brain.
A great example of how more detailed research often raises more questions than answers, and takes us deeper into the mysteries of evolutionary adaptation and development.
more on human ancestry
Homo erectus
This is a fantastic time to be interested in human origins.
[Ed Yong, ‘Not Exactly Rocket Science’]
The post linked to above, and probably plenty of others I could’ve linked to, makes my previous post on human origins look decidedly amateurish. But after all, I’m an amateur. And that’s all good, I’m just trying to educate myself here.
The Yong post doesn’t concern itself with how far back we can trace our distinctly human ancestry, but it does refer to the multi-regional model of origins, which I carelessly mentioned in my post, and it focuses on the latest analyses of our relations with Neanderthals, through computer simulations of the spread of populations and examination of the Neanderthal genome. It also mentions a recently discovered type of archaic human called the Denisovans, with whom we also interbred. This sounds confusing, as you might think we were archaic humans when we bred with them, but apparently not – or perhaps not quite so archaic as Denisovans.
It seems from my reading that ‘archaic’ here means a form that’s no longer extant, rather than a form that’s less developed or more ‘primitive’. Evidence of the Denisovans comes from a finger bone found in Denisova cave in Siberia, only in March 2010. Mitochondrial DNA from this hominin bone, which dated back 41,000 years, suggested that it was distinct from both Neanderthals and modern humans. Next, a team examined and sequenced the nuclear genome of this hominin [all from a wee finger bone], aided by the fact that DNA is better preserved in cold climates. As we know, the Neanderthal genome and the modern human genome have also been sequenced, and a comparison of results has shown that the Denisovans and the Neanderthals shared a divergent branch from the line leading to modern African humans. The branch diverged from the lineage some 800,000 years ago, with Denisovans and Neanderthals diverging from each other some 640,000 years ago.
That so much can now be gleaned from such scant fossil finds does tend to excite. Only last year another early species of Homo was identified, H gautengensis, through analysis of a specimen found back in the seventies in the Strekfontein caves of South Africa. This species is believed to predate H habilis, emerging more than two million years ago and dying out about 600,000 years ago. It was big-toothed and small-brained, little more than three feet tall, and weighing around 50kgs. It was bipedal on the ground but probably spent most of its time in trees, and it lived largely if not entirely on vegetable matter. Can we identify such a creature as human? It probably lacked speech or any language capacity. We can’t analyse its DNA, but anatomical and other research suggests it is a close relative of H sapiens, if not a direct ancestor.
These recent discoveries of possibly or probably new lineages are due to a convergence of new techniques and accumulated knowledge – we know better where to look and what to look for. More discoveries await analysis, and previous finds await reappraisal. It looks as if our Homo ancestry will get a lot bushier as a result. There’s a bit of a language issue here. Homo sapiens are clearly human beings, and they’re direct descendants of another Homo species. H erectus is the most likely candidate, but we’re far from sure. In any case, at the point of divergence there would’ve been little noticeable difference between our species and its immediate ancestor. This difficulty about beginnings is compounded by our naming the whole genus Homo, Latin for ‘man’, in the gender-neutral sense. The genus is more than 2 million years old, our species may only be about 200,000 years old. Many would argue that H gautengensis, given the description given above, is not human. Others would argue that it is, or at least that it is proto-human [though this is problematic as it suggests a human ‘prototype’, a rather teleological term]. So the original question, how long have humans been around is dependent both on how we define ‘human’, and on what we can properly infer from the data. For example, though we might be able to infer much about the lifestyle of H gautengensis [I don’t know how they managed to work out its probable diet] from modern analyses, we might never be able to know how we’d have reacted if we’d met a specimen. Would we see recognition in its eyes? Could we have befriended it [or him, or her]? How would we have communicated? It’s more likely, of course, that both groups would’ve exhibited in-group/out-group hostility, but even so, it’s hard to imagine what that hostility would’ve felt like, with its admixture of recognition, curiosity and wonder.
In any case, for those who might want to argue that the species H sapiens and H sapiens alone is truly human, there are more complications. In 1997 remains were found in Ethiopia of a probable subspecies of H sapiens, since named H sapiens idaltu, dating back 160,000 years. The remains consisted of three craniums, and who knows how many other remains are yet to be found, of this and other subspecies. So now we prefer to call ourselves H sapiens sapiens, but more of that another time.
how long have humans been around?
A memory keeps flashing back to me of an argument I was having with a Christian friend. I said something about humans being around on this planet for x number of years. No doubt I was making the point that if Christianity has only been around for 2000 years, why did their god not allow all those earlier humans to ‘know Christ’ and presumably therefore be saved? I’m hazy about the exact nature of the argument because we were both quite drunk at the time. Anyway, his response to my educated guess about the length of time humans have been around was ‘bullshit – that’s complete bullshit’. I was taken aback – it’s not as if my friend was a young earth creationist or anything, he just thought my guesstimate was way out. Trouble is, I can’t recall whether I’d said we’d been around for 200,000 years or 500,000 years or a million years or two million. How would I know?
So I’m going to have a go at answering this question here, but before I do I might just raise an obvious issue which may or may not be philosophical. If we decide, based on fossil or genetic evidence, that the first humans lived, say, 550,000 years ago, then what about the parents of those humans? Were they suddenly not human? Not likely. There would’ve been essentially no observable difference between the ‘first human’ and its parents, and then again no observable difference between those parents and their parents, and so on back down the line. So how can the human possibly begin at all? Can’t the human be traced back to the first living thing, which would therefore also be human, in some real sense?
This is surely more than a piece of pedantry. It points up the artificiality of species differentiation, when in fact everything and nothing can be differentiated. You could counter by saying that the differentiation becomes important when it has some significance, but that would be circular. What constitutes significance?
So maybe we can’t ultimately answer this question, but we can surely try for some sort of pragmatic answer. After all, we don’t categorise Homo sapiens as separate from Homo erectus for nothing, do we?
One approach used is the Adam and Eve approach, that’s to say mitochondrial Eve and Y-chromosomal Adam (I’m not sure about these designations, which play into certain hands – after all, in another, safely dead, tradition, the first woman was Pandora, another symbol of the evil woman] . Mitochondrial Eve is our matrilineal MRCA [most recent common ancestor]. I’ve already explained, in the recent post on Neanderthals, how mitochondrial DNA, as opposed to nuclear DNA, is passed down the female line without the recombination that is the product of meiosis or eukaryotic reproduction. In fact, due to its protection within the ovum it doesn’t undergo recombination at all. It follows that we can trace our mitochondrial DNA back to an MRCA, estimated at 200,000 years ago.
But MRCA doesn’t by any means equate to the first female human. This ‘Eve’ had plenty of contemporaries – sisters, cousins, parents and grandparents, who were obviously just as human as ourselves, it’s just that their descendents aren’t traceable to modern humans in an unbroken line. The story of Y-chromosomal Adam [or Adams] is quite a bit more complicated, and considerably less resolved, and I won’t tell it here. Suffice to say that, whether or not our male MRCA turns out to be older than mitochondrial Eve [our current candidate is much younger], the same problem arises – his parents and his great-grandparents will seem, to all intents and purposes, to be just as human.
So let’s leave genetics aside and turn again to the fossil record [I’ve written quite a bit on this already, e.g here, here, here, here, here and here]. As everyone should know, this record is scratchy and controversial. One of the problems is that, given normal human variation in cranial capacity and other measures, it’s often very difficult to distinguish between a fossil of [part of] a Homo sapiens and another Homo species, of which we may have only one or two [partial] specimens with which to make comparisons. We may with varying degrees of confidence claim that Homo sapiens evolved between 400,000 and 250,000 years, but it wouldn’t be unreasonable, surely, to claim that the species of Homo that preceded Homo sapiens was also recognisably human. We know now, for example, that Homo neanderthalensis was human enough to successfully breed with.
H erectus, a species believed by many to be ancestral to H sapiens, was generally thought to have died out about 400,000 years ago, but recent work on specimens found in Java in the thirties, have led them to be reclassified [always tentatively and controversially] as a sub-species of H erectus, dating back only 50,000 years, or less. And then there’s the recent H floresiensis, which may yet be reclassified. The extinct species H heidelbergensis, which flourished in Europe between 400,000 and 600,000 years ago, is also a candidate for our immediate ancestor, though it’s disputed whether H heidelbergensis is really a separate species of H erectus or H ergaster [whose existence as a separate species is also in doubt].
So are we any closer to answering our question? My uneducated guess is that all of these species and sub-species of Homo [and there are many more than I’ve mentioned here] are variants on a line of descent dating back two million years or so, and that terms such as ‘species’ here are often more misleading than helpful. This brings me to the ‘multiregional hypothesis’ of human descent, summarised in Wikipedia thus:
The hypothesis holds that humans first arose near the beginning of the Pleistocene two million years ago and subsequent human evolution has been within a single, continuous human species. This species encompasses archaic human forms such as Homo erectus and Neanderthals as well as modern forms, and evolved worldwide to the diverse populations of modern Homo sapiens sapiens. The theory contends that humans evolve through a combination of adaptation within various regions of the world and gene flow between those regions. Proponents of multiregional origin point to fossil and genomic evidence as support for their hypothesis.
All of which sounds more than plausible to me, especially as it allows me to say that humans have been on this planet, in some form or another, for nigh on two million years. It’s a particularly useful stat for baiting the religious – two million years and Jesus drops in only 2 thousand years ago. What about those poor lost souls scratching around for a million nine hundred and ninety-eight thousand years before that?
Anyway, it’s an intriguing story, so let’s keep on digging and researching to fill in the gaps or to create new conundrums for ourselves about ourselves.
more on our Neanderthal ancestors
more Neanderthal eye candy
To continue with my Neanderthal confusion, I’ll quote from the brief Cosmos article and try to tease out some meanings and investigate further.
Mitochondria reproduce asexually – without mixing of genes – so if they’re replicating a lot, as they need to do in continuously dividing sperm cells, they may build up deleterious mutations that are potentially lethal to their ongoing reproduction.
Okay, some questions. What exactly are mitochondria and why do they reproduce asexually? What are they doing in our sperm cells? Aren’t sperms ‘male’ as opposed to egg cells? But apparently mitochondria are found in female germ cells too. What’s going on?
Mitochondria are membrane-enclosed organelles found in eukaryotic cells. Above all, they generate ATP, providing the cell with chemical energy. And they do many other things – in fact, you could clearly spend a lifetime or several in investigating the properties of and the various functions of these wee beasties within cells, so I’ll try not to get too distracted. The number of mitochondria within particular cells varies enormously, from one to thousands, depending on the organism or the tissue. They have their own genome, quite separate from the DNA in the nuclei of their host cells. This genome is substantially similar to bacterial genomes, and this has famously prompted a hypothesis about endosymbiosis which is now, I think, generally accepted. But I digress. Or do I?
Presumably this symbiotic relationship between essentially bacterial mitochondria and eukaryotic cells means that the mitochondria exist in all cells of the eukaryotic organism, including the germ cells. ‘Continuously dividing sperm cells’ is a term that has thrown me – I was at first thinking of the continuously dividing germ cells of the blastula, but no, these are sperm cells continuously reproduced within the adult male. Nature being nature, this reproduction isn’t absolutely perfect every time and there’s the occasional mutation. This is a problem, as the mutations don’t just die off as they might in a different environment – but if a certain percentage of the replicated cells are mutant, wouldn’t that figure be constant as the cells multiply? But presumably these cells don’t just divide endlessly into hugely huge numbers… I’m thinking too much? Let’s return to the article:
Female germ cells, however, are held in a prolonged phase of dormant suspension from the moment of formation in late foetal life until just prior to ovulation. And so mitochondrial DNA in oocytes – female germ cells – is protected from mutations. For this reason, female parents pass on their mitochondrial DNA but male parents do not.
I get at least some of this. The female germ cells, with their mitochondria, are formed in late female life, and they don’t replicate ‘until just prior to ovulation’. What exactly is ovulation, then? By the word itself, I’d have thought ‘the formation of eggs’. So oocytes, female germ cells, aren’t themselves eggs. Forget that, they are eggs, and ovulation is about the discharge of an oocyte [or ovum] from a ruptured ovarian follicle. So the oocyte doesn’t change or replicate at all? It’s just discharged into – where? Down the fallopian tube, one egg per month [usually] in human females. By month, I mean, per cycle. If it doesn’t get fertilized, from its new position in the lining of the womb, it’s discharged through menstruation. Sorry, just getting this clear. What I do get is that the ova are ‘fully formed’ even before their female ‘owner’ is born. The female’s ovum becomes fertilized when a sperm cell penetrates the nucleus of the ovum, and its chromosomes combine with those of the ovum. The mitochondrial DNA remains the same, and of course is only carried on through the female line. I think I’m clear about this, more or less, for the first time.
Let’s go back again to the article:
Since Neanderthal mitochondrial DNA is absent in living humans, it suggests that any hybrid offspring who carried the mitochondrial DNA from Neanderthals didn’t contribute to the 4% of shared human-Neanderthal DNA.
The article then goes on to canvas a few theories as to why this might be so. But whatever the explanation, the fact is that the modern human genes traceable to Neanderthals are solely the result of male Neanderthals mating with female humans. And now we get to Haldane’s Law, which relates to the sex ratio of the offspring of hybrid animals. Basically, XY [male] progeny in such cases will be likely to be non-functional, non-existent or sterile, due to the high mutation rate of Y chromosome genes. So, more female progeny would be produced, but they have not turned out to be contributors to our gene pool