Another Mystery Ancestor Joins The Group

Science Daily has a story on genetic work done by researchers at Cornell University and Cold Spring Harbor Laboratory that suggests that there is, as yet, another unnamed ancestor to the modern human line. They write:

In the new paper, the researchers developed an algorithm for analyzing genomes that can identify segments of DNA that came from other species, even if that gene flow occurred thousands of years ago and came from an unknown source. They used the algorithm to look at genomes from two Neanderthals, a Denisovan and two African humans. The researchers found evidence that 3 percent of the Neanderthal genome came from ancient humans, and estimate that the interbreeding occurred between 200,000 and 300,000 years ago. Furthermore, 1 percent of the Denisovan genome likely came from an unknown and more distant relative, possibly Homo erectus, and about 15% of these "super-archaic" regions may have been passed down to modern humans who are alive today.

The paper is available in PLoS Genetics, which means that it is free to the public.  The above-description makes it sound like bootstrapping on stilts.  Here is a paragraph from the paper, itself, that describes the process:

In this paper, we describe a powerful and highly general new method, called ARGweaver-D, that samples ancestral recombination graphs (ARGs) [18–20] conditional on a generic demographic model, including population divergence times, size changes, and migration events. After introducing ARGweaver-D, we present simulation studies showing it can successfully detect Nea→Hum introgression, even when using a limited number of genomes, and that it also has power for older migration events, including Hum→Nea, Sup→Den, and Sup→Afr events. Finally, we apply this method to modern-day Africans and ancient hominins, and characterize both new and previously reported cases of introgression between humans and archaic hominins.

Okay, it still sounds like bootstrapping on stilts.  I am not sure how you can do a simulation to detect older migration events when that is what you are looking for in the first place.  What exactly is an ancestral recombination graph, you ask?  From a previous paper on this subject:

It is possible to capture these complex relationships using a representation called the ancestral recombination graph (ARG), which provides a complete description of coalescence and recombination events in the history of the sample. However, previous methods for ARG inference have not been adequately fast and accurate for practical use with large-scale genomic sequence data. In this article, we introduce a new algorithm for ARG inference that has vastly improved scaling properties. Our algorithm is implemented in a computer program called ARGweaver, which is fast enough to be applied to sequences megabases in length. With the aid of a large computer cluster, ARGweaver can be used to sample full ARGs for entire mammalian genome sequences.

The best data we have suggests that Neandertals and African archaics split some 600 ky ago when a group of Homo ergaster migrated out of Africa and took up residence in western Europe, leading to branching events that eventually included H. antecessor and the Neandertals.  This is supported by this research, which found about 7% introgression into the Neandertal genome of archaic H. sapiens.  The surprise was that 1% of the Denisovan genome likely came from an, as yet, undiscovered hominin.  

Increasingly, there is evidence that considerable interbreeding occurred throughout the middle to late Pleistocene, continuing through the interbreeding that occurred in China and Europe.  As I wrote about the 105-130 ky old Chinese Xuchang skulls:

These two Chinese skulls stand at the crossroads of these population movements. While showing clear Neandertal characteristics, they also express modern traits, possibly reflecting mixing with the late, modern human arrivals represented by the recent modern human finds at Daoxian. Yet they also express a clear link to ancient East Asian populations. The implications of these skulls are stark: there has been widespread population mixing and regional continuity in Europe and Asia for at least 400 thousand years. Not only did the Neandertals feel enough cultural kinship to mate and have children with these East Asian people, the early modern humans coming out of Africa did, as well. As Chris Davis of China Daily News put it: “One big happy family.”

This likely represents only a small part of the vast scope of population mixing. I will be curious to see where the ARG research leads.

Chris Stringer: Meet the Relatives

Chris Stringer has a post in the Financial Times titled Meet the Relatives.  It is sort of a whirlwind tour through the evolution of the genus Homo.    He writes:

The discoveries of Homo floresiensis, Homo luzonensis, Denisovans and Homo naledi in the past 15 years remind us that the fossil record of humans is still very patchy — stone tools are scattered across much of Africa as a witness to widespread human occupation, yet fossil evidence has been recovered from less than 10 per cent of that continent’s area.

The percentage coverage for Asia is hardly any better: there is, for example, currently only one significant human fossil from the whole of the Indian subcontinent. The discoveries of the past few years underline just how much evolutionary history remains unknown, with other extinct lineages no doubt still to be revealed.

Many of the new finds challenge how we classify fossils in relation to Homo sapiens today. I continue to call the Neanderthals a different species from us, based on their distinctive skeletons and skulls; others feel that the recent evidence of interbreeding and increasing evidence of sophisticated behaviour mean that we should merge them, and the Denisovans, into our species.

I think that the discovery of the Xuchang hominins indicates that there has been considerable population mixing for several hundred thousand years.  As I wrote at the time:

These two Chinese skulls stand at the crossroads of these population movements. While showing clear Neandertal characteristics, they also express modern traits, possibly reflecting mixing with the late, modern human arrivals represented by the recent modern human finds at Daoxian. Yet they also express a clear link to ancient East Asian populations. The implications of these skulls are stark: there has been widespread population mixing and regional continuity in Europe and Asia for at least 400 thousand years. Not only did the Neandertals feel enough cultural kinship to mate and have children with these East Asian people, the early modern humans coming out of Africa did, as well. As Chris Davis of China Daily News put it: “One big happy family.”

Whether this represents such behavior at the peripheries of different species or that of one polytypic species is, as yet, unclear.  It is very clear that our understanding of how these populations interacted is rudimentary, at best. 

Neandertal Teeth 450Ky Old Found in Italy

The Smithsonian is reporting that excavations in Italy have uncovered teeth dated to 450 thousand years ago that have Neandertal characteristics.

A fossil tooth study published today in the journal PLOS ONE analyzes some of the oldest human remains ever found on the Italian Peninsula. The teeth, which are some 450,000 years old, have some telltale features of the Neanderthal lineage of ancient humans. Dating back to the Middle Pleistocene, the fossils help to fill in gaps in an intriguingly complex part of the hominid family tree.

The species Homo neanderthalensis shares an unknown common ancestor with our own species, Homo sapiens, but it’s unclear exactly when the lineages diverged. Homo sapiens evolved perhaps 300,000 years ago, according to the fossil record, while Neanderthals’ evolutionary timeline has proven even trickier to pin down. Some genetic studies suggest that their lineage split from our own as long as 650,000 years ago, but the oldest definitive fossil evidence for Neanderthals extends back only about 400,000 years.

Conventional wisdom is that Neandertals emerged around 200 thousand years ago, in Europe. The Atapuerca Sima de Los Huesos remains, which show pre-Neandertal characteristics, are about the same age as the Italian remains. It has been suggested that Homo heidelbergensis is the common ancestor to both Neandertals and modern humans but this is far from clear. The genetics suggests that Neandertals and modern humans split around 600 thousand years ago but interacted as recently as 60 to 70 thousand years ago and interbred.Modern Europeans have between 3 and 6% Neandertal genes. 

This pushes back the origins of Neandertals and further muddies the picture of when and where these groups were and how they interacted.  More puzzle pieces. 

Modern Humans Came Out of Africa Earlier Than Thought and Did So Multiple Times

If you have been studying human evolution, this story is not new.We have suspected for some time that humans migrated out of Africa in waves, beginning with Homo heidelbergensis, up through archaic Homo sapiens and, now, modern Homo sapiens.  As the story notes, there have likely been multiple migrations of Homo sapiens, as well. 

From the story in Science Daily:

A review of recent research on dispersals by early modern humans from Africa to Asia by researchers from the Max Planck Institute for the Science of Human History and the University of Hawai'i at Manoa confirms that the traditional view of a single dispersal of anatomically modern humans out of Africa around 60,000 years ago can no longer be seen as the full story. The analysis, published in the journal Science, reviews the plethora of new discoveries being reported from Asia over the past decade, which were made possible by technological advances and interdisciplinary collaborations, and shows that Homo sapiens reached distant parts of the Asian continent, as well as Near Oceania, much earlier than previously thought. Additionally, evidence that modern humans interbred with other hominins already present in Asia, such as Neanderthals and Denisovans, complicates the evolutionary history of our species.

Here is the graphic from the story:

 
What is only hinted at in the article is that when these waves of moderns came out of Africa, they interbred with the archaic hominins that they encountered. Further, this genome was remarkably stable, since there is genetic evidence that there was at least 500 thousand years of separation between them.Also missing from the story is the range of variation that these hybridizations display.  For example, as noted by the triangle on the map, the Xuchang fossils from China seem to show a mix of modern, Neandertal and late Homo erectus morphologies.  As I noted at the time:

The implications of these skulls are stark: there has been widespread population mixing and regional continuity in Europe and Asia for at least 400 thousand years. Not only did the Neandertals feel enough cultural kinship to mate and have children with these East Asian people, the early modern humans coming out of Africa did, as well.

The other peculiar thing about the graphic is that there seems to be no migration pattern through the strait of Gibraltar. This seems odd since this is likely at least one of the routes that were taken by H. ergaster between 1.5 and 2.0 mya, and since it is thought that the Levallois tool technology comes from the Middle Stone Age of Africa, this would have been a likely route of introduction.  There may have been a barrier of sorts, suggested by the fact that the latest surviving Neandertals are from Spain. 

New DNA Analysis Allows for Greater Understanding of Modern Human Prehistory

From Science Daily:

A University of Utah-led team developed a new method for analyzing DNA sequence data to reconstruct the early history of the archaic human populations. They revealed an evolutionary story that contradicts conventional wisdom about modern humans, Neanderthals and Denisovans.

The study¹ found that the Neanderthal-Denisovan lineage nearly went extinct after separating from modern humans. Just 300 generations later, Neanderthals and Denisovans diverged from each other around 744,000 years ago. Then, the global Neanderthal population grew to tens of thousands of individuals living in fragmented, isolated populations scattered across Eurasia.

"This hypothesis is against conventional wisdom, but it makes more sense than the conventional wisdom." said Alan Rogers, professor in the Department of Anthropology and lead author of the study that will publish online on August 7, 2017 in the Proceedings of the National Academy of Sciences.

As the authors note, there is mounting evidence of a migration from Africa to Europe, likely by way of the Strait of Gibraltar, in which Acheulean stone tools are introduced by a group which became known as Homo heidelbergensis.  This group, subsequently, split, likely gave rise to the Neandertals  and the Denisovans a bit later.  Then, a second wave of migrations around 90 to 100 ky happened, during which there was hybridization between Neandertals, moderns and Denisovans.

We live in a time where we now have the genomes of archaic Africans, Eurasians, Neandertals, Denisovans and early moderns and can compare them using site pattern analysis.  These authors found that

• In contrast to previous studies, this one indicates that Neandertal population size was large, on the order of tens of thousands of people, in isolated populations
• The split between the Neandertals and Denisovans was early, on the order of 744 thousand years ago.  
• By the time you find these hominins in the fossil record, they had already split from the Denisovans, which explains why the Atapuerca Sima De Los Huesos hominins resemble Neandertals more than Denisovans.
• Therefore, Neandertal features are thought to have emerged over a long period of time in Europe. 

This analysis will help us rethink our understanding of the fossil material from Gran Dolina, which now likely represents a population from which both the Denisovans and Neandertals split.  This makes sense, given the general, non-derived nature of the fossil material from there.  Things are slowly (maybe?) falling into place.

¹Alan R. Rogers, Ryan J. Bohlender, and Chad D. Huff. Early history of Neanderthals and Denisovans. PNAS, August 2017 DOI: 10.1073/pnas.1706426114

Genetic Data Indicates Another Migration of Archaic Homo sapiens Out of Africa

Ars Technica is running a story based off of a Nature Communications article about a migration of archaic Homo sapiens out of Africa that took place more recently than the one at c. 650 kya that was hypothesized to have given rise to the Neandertals. Cathleen O'Grady writes:

The picture painted by nuclear DNA (nDNA) is that, between 765,000 and 550,000 years ago, our ancestors in Africa diverged into two groups. One group would eventually lead to our own species, although we wouldn't make an appearance until around 200,000 years ago. The other group would lead to Neanderthals and the closely related Denisovans. This proto-Neanderthal/Denisovan group left Africa for Eurasia at some point; sometime around 430,000 years ago, they diverged into distinct Neanderthals and Denisovans.

But the picture painted by mtDNA is different. Neanderthal mtDNA is more similar to modern humans than it is to Denisovan mtDNA. And the divergence date between us and them, when estimated based on mtDNA, is much more recent—between 498,000 and 295,000 years ago.

Some researchers have suggested that you can explain this mixed genetic evidence if Neanderthals interbred with another, more recent African group of humans. This would provide them with different mtDNA after they split from Denisovans. And that, in turn, means that there must have been humans, closely related to our own species, who left Africa for Europe far earlier than previously suspected.

It is not such a stretch to suggest that the recent finds from Jebel Irhoud may be a population related to this mystery population.  The Jebel Irhoud crania show modern characteristics in the face and have been placed in the modern Homo sapiens clade (if provisionally).  Whether or not they have enough traits found in later humans to be the stem group of anatomically modern Homo sapiens is not currently known.  Jebel Irhoud is a hop, skip and a jump to Gibraltar, which we know had already provided an avenue of migration for earlier populations of early Homo which gave rise to Homo heidelbergensis in Europe.

As the story notes, there are remarkable similarities in stone tool technologies between the northern  African Middle Stone Age and the European late Acheulean and early Mousterian tools.  There are Levallois flakes found in both areas, as well as similarly-made knives and points.  This suggests that populations in North Africa had some contact with those of southern Europe.  As we push the age of the modern human clade back in time, these discoveries help to frame the appearance of modern humans and how they interacted with the populations around them.  Exciting times!

The Nature Communications article, Deeply divergent archaic mitochondrial genome provides lower time boundary for African gene flow into Neanderthals can be found here and was free when I read it.

New Study on Homo naledi

Lauren Schroeder and colleagues have published a report on the skull of Homo naledi, in which they address the characteristics and attempt to place them in a taxonomic context, using morphometric analysis.  From the abstract:

Our results indicate that, cranially, H. naledi aligns with members of the genus Homo, with closest affiliations to H. erectus. The mandibular results are less clear; H. naledi closely associates with a number of taxa, including some australopiths. However, results also show that although H. naledi shares similarities with H. erectus, some distances from this taxon – especially small-brained members of this taxon – are extreme. The neighbor joining trees place H. naledi firmly within Homo. The trees based on cranial morphology again indicate a close relationship between H. naledi and H. erectus, whereas the mandibular tree places H. naledi closer to basal Homo, suggesting a deeper antiquity. Altogether, these results emphasize the unique combination of features (H. erectus-like cranium, less derived mandible) defining H. naledi. Our results also highlight the variability within Homo, calling for a greater focus on the cause of this variability, and emphasizing the importance of using the total morphological package for species diagnoses.

Another major finding of the study is that a grouping of H. naledi and specimens of Homo erectus "exceeds, in many instances, what we would expect if this grouping represented a single species."  Recall that we have zero idea how old this find is and, to the extent that this is possible, are trying to place this skull using only taxonomic analysis. Nonetheless, it gives us more information about this stage of hominin evolution and suggests that there was considerable variation of morphs running around during the transition from the australopithecines to early Homo. 

Of Stone Tools and Human Cognition

One of the things that is taught in human origins classes all over the world is that the earliest stone tools were likely made at the site of Dikika, and date to around 3.4 million years ago.  That perspective has now been called into question with the observation that monkeys can create exactly the same kinds of tools—by accident. Sarah Knapton, writing in the Telegraph has this:

In a discovery that calls into question decades of research, a band of wild bearded capuchin monkeys in Brazil were seen hammering rocks to extract minerals, causing large flakes to fly off.

Previously archaeologists believed the flakes were only made by humans through a process called ‘stone-knapping’ where a larger rock is hammered with another stone to produce sharp blade-like slivers which can be used for arrows, spears or knives.

The flakes were thought to represent a turning point in human evolution because they demonstrated a level of planning, cognition and hand manipulation that could not be achieved by other animals.

But the new research suggests that flakes can be made without any such foresight. In fact they can simply be made by accident.

“The fact that we have discovered monkeys can produce the same result does throw a bit of a spanner in the works in our thinking on evolutionary behaviour and how we attribute such artefacts,” said Dr Michael Haslam, lead of the Primate Archaeology project at the University of Oxford.

This is possible and it may be that some of the earliest “tools” aren't any such thing. When hominins started using tools in a concerted fashion has always been a large question in the evolutionary picture. It is very clear that by what we know as the Acheulean, manufactured by Homo ergaster, Homo erectus and Homo heidelbergensis, the hand axes are clearly human-made. Before that, maybe more research needs to be done to verify that what we think is human behavior actually is.  It is natural to want to impart human intelligence to our ancestors as far back as we can, in an effort to “humanize” them but, sometimes, this might be just wishful thinking.

Humans and Fire

It had been conventional wisdom that the origin of bipedality occurred in a forest/fringe environment and that a move to the savannah during the dry-out at the end of the Pliocene accelerated the evolution of humans.  That was thrown into turmoil when it was discovered that Ardipithecus ramidus possessed facultative bipedal characteristics at 4.4 million years but lived in an entirely forested environment.

Now, it seems, the savannah is seen as playing a different role in human evolution.  Charles Q. Choi, of Scientific American writes:

A longtime theory holds that early humans discovered how to use fire accidentally—perhaps while making stone tools they found that striking rocks against each other could generate sparks, and then gradually learned fire had many uses.

The problem with such serendipity-based explanations is that they "raise more questions than they answer," says evolutionary anthropologist Christopher Parker at the University of Utah in Salt Lake City. For example, these theories do not address when or where the discovery might have occurred, why it did not happen earlier or why other animals that use stone tools—chimpanzees, capuchin monkeys, crab-eating macaques and sea otters are known to do so—did not also develop fire use, Parker notes.

Parker and his colleagues suggest in a study published in the April Evolutionary Anthropology that humans developed fire use as a natural response to environmental changes. Previous research found that roughly 3.6 million to 1.4 million years ago—as the genus Homo emerged in Africa—the continent regularly experienced bouts of aridity, causing forests to shrink and dry grasslands to spread. Earlier studies suggested these climate shifts may have driven humanity’s ancestors away from a life climbing trees and toward one of walking upright on the ground, Parker says.

Yes, but there have been, as alluded to above, issues with these previous studies. If bipedality originated in the forest, as a response to who-knows-what, then they already possessed it when the drying out began. But this is not the crux of Parker's research:

Parker and his colleagues suggest in the new study that our ancestors not only grew accustomed to fire but learned to exploit it as a naturally occurring resource. This adaptation, called pyrophilia, may have set the stage for more active and deliberate human use of fire.

The research team's models suggest early humans benefited from wildfires in a number of ways: The blazes would have made it easier to find food, much as Martu Aboriginal women in Australia still rely on fire to clear brush for more efficient hunting. The models also indicate that early humans might have combed the charred remains of wildfires to dine on animals, seeds, nuts and tubers cooked in the flames—benefitting from a chemical process that not only makes many foods easier to digest but kills germs and neutralizes some toxins.

This has not been proposed before and it will be interesting to see if more evidence of this is found. Read the whole thing.

The Importance of Schöningen to the Story of Human Evolution in Europe

A lake site in northern Germany, near Schöningen, has lifted much of the veil of how advanced Homo heidelbergensis was during the later Lower Palaeolithic.  As Heritage Daily reports:

The excavations in the open-cast coal mine in Schöningen running from 1994 until today show that we have long underestimated the cultural capacities of Homo heidelbergensis. Schöningen is a key site for documenting both a high resolution record of past climatic change and how hominins lived in northern Europe during the Ice Age. Since 2008 Professor Nicholas Conard and Dr. Jordi Serangeli of the University of Tübingen have led the excavations with a major international research team in close cooperation with the Cultural Heritage Office of Lower Saxony.

the Journal of Human Evolution is making available for a time, all of the papers of a special issue on the site. That is how important it is. That link is here. 

What has been discovered, since the opening of the excavations, is that Homo heidelbergensis created advanced bone and stone implements, engaged in complex hunting behaviors and exhibited behaviors consistent with a high level of “planning depth.”  Further, they appear to have lived in a society with divisions of labor and a highly advanced communication system.

This has been referred to by the authors of one of the papers as “paradigm shifts in human evolution” and appears to represent, at least at this site and at this time period, a radical change in the way that humans were dealing with their surroundings.  In other words, at around 300,000 years ago, we seem to have the roots of modern human behavior, in Europe.  How much earlier this behavior actually shows up is, at the moment, anybody's guess.

Dennis Venema on Human Evolution and Palaeogenomics

Dennis Venema is doing the genetics end of human evolution.  He has, as with most evolutionary creationists, taken the long view of creation, to the point where he has publicly stated that the modern human genome could not possibly have originated with two individuals.  Knowing what I do of the fossil record (upcoming BioLogos posts on June 16-18), I have no problem with that.  He focuses on palaeogenomics, and writes:

The discovery of Neanderthal remains in the same location that preserved the exceptional Denisovan DNA at last provided a very high quality Neanderthal genome, the analysis of which was published just this year. This new data allowed for several more robust analyses comparing human, Denisovan, and Neanderthal genomes. These analyses produced several noteworthy results: modern mainland Asian populations also have a small amount of Denisovan DNA; humans contributed some DNA variation to Neanderthals; Neanderthals and Denisovans interbred, with DNA variation flowing both ways; and (perhaps most interestingly) Denisovans have DNA variation that suggests they interbred with yet another archaic hominin group, possibly Homo erectus.

While the palaeogenomic data indicate a split time of c. 600 Ky years for modern humans and Neandertals, it is fairly clear from other genetic evidence that there was at least some interbreeding between early moderns and Neandertals all the way up to around 50 Ky B.P. (perhaps as recently as 29 Ky, given the information from the Portuguese burial at Lagar Velho), as well as interbreeding between the newly emerging African moderns and African archaic Homo sapiens. 

The news that the Denisovans have some very archaic DNA in them is not surprising.  IF modern humans and Neandertals split around 600 Ky B.P., the only people running around on the landscape at that point were early archaic Homo sapiens/late Homo erectus.  The salient feature of the name "archaic Homo sapiens" is that it is not a taxonomic name but rather a linguistic "catch-all."  The primary reason for this is because, as I noted in my series on human origins, the earliest members of this group still have some Homo erectus characteristics, while the later ones look more modern.  When these fossils, which all date to between (possibly ) 800 and 400 Ky B.P., were pulled out of the ground, researchers did not know what to call them, so they applied this "catch-all."  Adding to the confusion is that some of the archaic Homo sapiens crania from Africa bear more than a passing similarity to some of the finds in Europe.  All were clearly transitional but what to call them was a mystery.  Researchers such as Bernard Wood, applying systematics to the problem, have suggested that these forms should be given the name Homo heidelbergensis.  Such a taxon would, however, have quite a lengthy geomorphochronocline, stretching its limits, perhaps, to the breaking point. For a refresher on these fossils, you might want to read this post. 

So, if the split between modern humans and Neandertals was around 600 Ky B.P., who would have been the progenitors of these groups?  Modern humans don't appear on the landscape until between 160 and 190Ky B.P.  Neandertals don't appear until maybe 300 Ky B.P.  Here is one possible scenario. Sometime prior to 600k B.P., there was a migration out of Africa by one or more groups of archaic Homo sapiens/late Homo erectus.  This explains the similarities between the Petralona and African Kabwe crania, as well as that of the Gran Dolina remains and the African Bodo cranium.  In Africa, the archaics went about their business being archaic until around 200 ky B.P., when the modern genome began to arise (in response to what?).  In Europe, over time, in the face of not one but two ice ages (The Riss and Würm), one group evolved into the Neandertals, who's remains are found in Europe, the Levant, northern Iraq and very western Russia. Populations in the two areas would have, depending on the level of gene flow in the circum-Mediterranean area, become genetically isolated.

Now here is the really odd thing.  When these groups reunited, so to speak, they discovered that, not only was there an attraction, they were still genetically compatible after some 500 thousand years apart—to a point. Even though they actually produced viable offspring (and the presence of Neandertal genes in modern humans demonstrates that they were), because the Neandertal and modern human genomes were "optimized" if you will, eventually over time, hybrid depression would likely have ensued, reducing the fitness of the hybrid offspring.  This may account for the ultimate demise of the Neandertals, who had a genome that, with the warming at the end of the early Würm stadial, was likely undergoing negative selection pressure.  If, in fact, there was a swamping of the Neandertal genome by arriving moderns through the gates of Europe, this would have sped up the process.

This scenario is bare bones at best but explains much of the fossil data.  It leaves aside the hotly contested notion of whether or not Neandertals were a separate species from the early moderns and, with them, reflected a syngameon, or whether, as Milford Wolpoff contends, they reflect a widely polytypic species that interbred at the peripheries.  That is for another day. 

Study: Neandertal Speech and Language Abilities Like Modern Humans

Science Daily has a story on Neandertal speech.  Work by Dan Didiu and Stephen Levinson suggests that Neandertals and modern humans share a common ancestry with regard to the use of language.  Science Daily writes:

Dediu and Levinson review all these strands of literature and argue that essentially modern language and speech are an ancient feature of our lineage dating back at least to the most recent ancestor we shared with the Neandertals and the Denisovans (another form of humanity known mostly from their genome). Their interpretation of the intrinsically ambiguous and scant evidence goes against the scenario usually assumed by most language scientists, namely that of a sudden and recent emergence of modernity, presumably due to a single -- or very few -- genetic mutations. This pushes back the origins of modern language by a factor of 10 from the often-cited 50 or so thousand years, to around a million years ago -- somewhere between the origins of our genus, Homo, some 1.8 million years ago, and the emergence of Homo heidelbergensis. This reassessment of the evidence goes against a saltationist scenario where a single catastrophic mutation in a single individual would suddenly give rise to language, and suggests that a gradual accumulation of biological and cultural innovations is much more plausible..

I am still a bit “iffy” on the whole “common ancestor of modern humans and Neandertals” thing since some are trying to argue for a common ancestor based on the material from the Gran Dolina, in Spain, and it sure as all get out looks like modern humans originated in Northeast Africa at, or near, Herto. I have a tendency to think that there was a good deal of panmixia throughout Europe and north Africa.  Otherwise, we are required to believe that there was a species split at H. antecessor into what became modern humans (how'd they get to north Africa?) on one side and Neandertals on the other and that, some 700 to 720 thousand years later, emerging moderns and Neandertals encountered one another and interbred.  That is overly simplistic, I am sure but it seems far-fetched.  It seems easier to argue that the H. antecessor material represents an archaic Homo sapiens population that was the precursor (or something like it was) to later archaics, such as Petralona and Atapuerca, out of which Neandertals came.  Then the Neandertals interbred with the north-moving moderns and somewhere in there, the Denisova population split off.  The panmixia in Europe, western Asia and Russia explains why moderns have both Neandertal and Denisovan genes, along with the modern genes that originated in North Africa.  Subsequent swamping of the archaic genome led to the demise of both the Neandertals and Denisovans.   

Middle Pleistocene Hominin Height

Science Daily has a story on work being done with the material from the Sima de los Huesos cave at Atapuerca. 27 complete long bones have been discovered there and from these, it has been possible to estimate the height of Homo heidelbergensis. Science Daily writes:

The results suggest that both men and women in the Sima de los Huesos population were on average slightly higher than Neanderthal men and women. "Neither can be described as being short and both are placed in the medium and above-medium height categories. But, both species featured tall individuals," assured the experts.

The height of these two species is similar to that of modern day population of mid-latitudes, like in the case of Central Europe and the Mediterranean.

The humans who arrived in Europe during the Upper Palaeolithic era, Cro-Magnons or anatomically modern humans, replaced the Neanderthal populations. They were significantly taller than other human species and their average height for both sexes was higher, falling in the very tall individual category.

Height remained the same for some 2 million years.

We know from the remains at Turkana that, at least for some individuals, height close to that of modern humans had been achieved by 1.3 million years ago.This probably reflects (amongst other things) a massive increase in protein in the diet, which would come about by increased hunting, something present in late African Homo ergaster. More pieces of the puzzle.

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Another Species of Homo??

There is, if you believe the work coming out of Max Planck Institute. According to an article in Der Spiegel:

The human family just got a new relative. Genetic researchers in Leipzig have deciphered the DNA of a hominid species that coexisted with Homo sapiens and Neanderthals around 40,000 years ago. A tiny piece of bone was enough for them to sequence the genome.

The miniscule amount of powder could have sat on a knife point, and yet, according to Johannes Krause, it contains something sensational. The Leipzig-based genetic researcher extracted the fine powder from a minute piece of fossilized bone -- and discovered a whole chapter of mankind's history inside it.

One wonders why the remains of such have not been found. No matter. Onward. This is a follow-up to a story that, somehow, escaped my notice earlier this year, the discovery of the Denisova girl. She, apparently is the representative of a new species of Homo that split off from the main line around 300,000 years ago, and lived in the steppes and Siberia. The speculations are almost lurid:

The scientists posed the question as to how different types of hominids might have interacted with each other. Did they hunt each other? Did they avoid each other? Might they have stolen each other's women? To find the answers to these questions, the Max Planck scientists compared DNA from the Denisova cave with that of modern man. They found no traces of Denisova characteristics in people from Africa, Europe or China. Indeed, clear indications of intermingling were only found among the inhabitants of Papua New Guinea.

The two types of hominids, researchers believe, must have encountered each other somewhere in Southeast Asia. They hypothesize that different Denisova tribes had settled there long before modern man made his way to East Asia some 30,000 years ago. The two groups must have interbred, perhaps not as a matter of course, but periodically. Later, the modern humans and their genetic dowry moved further south, whence today's Melanesians developed.

The Leipzig researchers now want to search Russian and Chinese collections for more fossils that could belong to the Denisova. The hope is to understand what they may have looked like. While the DNA provides hints on several characteristics of the Denisova, appearance is not one of them.

This is not out of the question, since hominids in this time range all belong to that kitchen sink, catch-all grade “archaic Homo sapiens,” which encompasses basically everything that succeeded Homo heidelbergensis up to modern Homo sapiens. It also means that the human family tree is considerably more bushy than we thought at this point in time.

On the other hand, if they found traces of intermingling with Melanesians and other Asian groups, it is not clear how “specific” these individuals were. The original authors have remarked that the Denisova girl represented an out-of-Africa migration, a conclusion that has been challenged by Martinón-Torres et al. ¹ These authors write:

The evidence that the ancestors of Neanderthals (i.e., H. heidelbergensis) left Africa ca. 500–300 ka is currently inconclusive, and the origin of H. heidelbergensis remains enigmatic. Whilst dispersals out of Africa might have occurred ca. 1.0 Ma, large-scale dispersals within Asia were also probable, and thus an Asian origin of the Denisovans cannot be excluded. These issues cannot be resolved without substantial improvements in the dating of key specimens, without an enlarged Asian fossil hominin record (particularly from SW Asia), and without a much more detailed Middle Pleistocene climatic record from SW Asia and NE Africa. Although the Denisova evidence is undoubtedly a fascinating piece in the jigsaw puzzle of human origins, it would be premature at present to determine the part of the picture to which it belongs.

Given what we know about Neandertal DNA showing up in the modern human genome, the remains from Denisova may yet suggest a very wide-range polytypism in the human record during the transition from archaic to modern Homo sapiens.


¹Martinón-Torres, M., Dennell, R., & Bermúdez de Castro, J. M. (2011). The Denisova hominin need not be an out of Africa story. Journal of human evolution, 60(2), 251-255.

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“Oh, My Aching Back!”

Researchers working with human fossil material between 400 and 500 thousand years ago, from the Sima de Los Huesos, have discovered a Homo heidelbergensis individual that had some serious back issues. Susan Uzel of Cambridge News reports:

Found among the bones of around 28 people at a site called Sima de los Huesos – “pit of bones” – in northern Spain, the lumbar spine was reconstructed from fragments discovered by scientists from the Centro Mixto de Evolución Humana in Burgos.

The lumbar spine comes from the same man as a pelvis found in 1994. It is thought he was aged 45, and lived more than half a million years ago.

The way in which the bones developed and the way they changed due to wear and tear show he was likely to have suffered severe back pain.

Dr Gomez-Olivencia said: “It appears that we are looking at the spine of a man who had several different problems, including inversion of the curvature of the back, spondylolisthesis, and Baastrup disease – which are associated with pain today.”

Homo heidelbergensis were nomadic hunter gatherers, relying on animals such as red deer for food, and a damaged spine would have made hunting impossible.

This is not so unusual. With bipedalism comes all sorts of issues with the back. We put an incredible amount of strain on the lower vertebrae, which often causes herniation of the discs. As we get larger and heavier (read: fatter), these get exacerbated.

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