Lessons of Homo naledi

New discoveries of fossilised hominin remains have to varying degrees helped to shape our ever-morphing interpretation of hominin evolution. Homo naledi is a case in point.

Though many worker in the field of palaeoanthropology were disappointed with the confirmed Middle Pleistocene age of the Dinaledi remains, this news nevertheless fills a void in our understanding of Middle Pleistocene evolution.

H. naledi confirms what we have known since the astonishing discovery of Homo floresiensis, namely that small brained hominins continued to thrive in some part of the planet right up to recent times. H. naledi can now join Homo floresiensis in the small brain Middle to Late Pleistocene club.

Palaeoanthropologist can now exercise a high level of skepticism on dating hominin fossilised remains using morphological stucture and statistics. In 2015, palaeoanthropologist John Francis Thackeray concluded Homo naledi to be over 1.5 Ma, while Mana Dembo and her colleagues concluded an age of 930,000 years of age for the Rising Star remains. Though Dembo et al were closer to actual age of the remains, they were still nearly 600,000 years off.

Finally, H. naledi continues to confirm what we have known since the announcement of Australopithecus sediba that hominin evolution features an ever changing mosasicism. With Australopithecine-like shoulders and cranium, while the lower limbs and foot appears more derived.

Doctoral student addresses critics of the Cerutti Mastodon Controversary

An anonymous doctoral student associated with the Cerutti Mastodon research addresses critics on Reddit as follows:

First off, my qualifications: My current advisor is the third author on this paper and I worked under (and collaborated with) the second author when I worked at the San Diego Natural History Museum (in fact, I re-prepared some of the material in this paper about 6 years ago). Furthermore, I am a doctoral student in the final months (hopefully) of my PhD. My dissertation work has been on proboscideans (elephants and their relatives), but I have also done a fair amount of work on cetaceans (whales) and other vertebrates.

As far as the dating methods go, this site was dated using multiple types of absolute dating methods, which all resulted in a very similar age. However, the Uranium-series dating (not to be confused with radiocarbon dating, which could not give you an accurate age this old) that was used here got results with a very high confidence. In fact there is essentially no evidence of alteration that might lead to an older date (which really would not be common anyways). The dates recovered are almost unimpeachable (and I don’t say that lightly). I would be very surprised if a geochronologist or any other expert had a major problems with the dates themselves (in fact a geochronologist was a reviewer for this paper for just this reason). Also, to the people that are saying that it is perhaps time to reassess our methods of isotopic dating in general, I strongly suggest you spend more time researching and trying to understand these methods before you make a claim like this…

One other misconception that I keep seeing here are peoples’ interpretation of what is meant by “human” in this paper. “Human” is meant here in the sense of a species of the genus Homo, not necessarily Homo sapiens specifically. In fact, because of the old age it seems fairly unlikely that this would be the modern species of human rather than some other [unknown] species.

I’m sure there will be other questions or comments here throughout the next day or so, and I will try to check in from time to time and update this post. I’m also happy to answer any questions that I can (to the best of my knowledge).

Edit 1: To the folks wondering if this site could have been scavenged by humans (as opposed to hunted), I would say that, that is absolutely possible. In fact there is really no evidence one way or another to argue for hunting over scavenging at this site, and I don’t believe that this paper takes a stance on this either. In fact, I would say that the argument of hunting vs scavenging in association with this mastodon is somewhat irrelevant. What is important is that this extremely old site (relatively speaking, anyways) has fairly clear association with ancient human activity.

Edit 2: Several people have pointed out that the article discusses a lack of evidence of meat stripping on the specimen. This does suggest scavenging, as it likely means the soft tissue was at least somewhat rotted and not usable.

Edit 3: Many people are suggesting that this animal could have been scavenged or had its bones modified many thousands of years after its death (i.e., implying the tools are much younger than the mastodon). To that point 1) the type of breakage seen on these bones is indicative of damage while the bone was still fresh. Fresh bone (sometimes called “green bone”) breaks in a very different “spiral pattern” than older dried out bone; and 2) you have to remember that the sediments that the tools and mastodon are found in represent the context in which they were buried. Therefore since these materials were all found within the same layer they must have been buried at the same time. It is possible that ancient humans exhumed old bones (though I know of no actual evidence of this), but we would see telltale signs of disturbance to the sediment (which was not observed here).
In other words, I don’t think that arguments about this site will come down to whether the material is associated and coeval, but whether folks think that these artifacts are indeed stone tools. Those people who do not agree with this identification will then have to reconcile the crazy taphonomy at this site and attribute it to some other natural process (which will be no small feat, IMHO).

Edit 4: For the people asking why we don’t have any evidence of humans (or human remains) in North America in the time between the age of this site and more generally accepted dates:

First off, I would just like to note that we are almost certainly not talking about a direct lineage of humans between the time of this site and those of Clovis times (in fact, as I’ve stated above, we are likely not even talking about the same species). This was likely a very small population of humans that made it to North America that probably died out long before the modern species of human ever made it over. In that sense, there isn’t necessarily a gap of time to “bridge”.

As for why potential sites might not be preserved: There are a couple of reasons that you might not have evidence of humans found from this time. First off, you may not have rocks of the right age readily exposed in the region where the individuals were living (which is somewhat the case on the west coast, as far as I am aware). Second, the individuals could be living in an environment that is not conducive to preserving fossils (e.g., organisms that live in montane environments tend to not preserve in the fossil record because sediments are not being deposited in those regions). Third, getting preserved in the fossil record (in general) is very rare, and if your study organism has a very small population size or is short lived (as we would expect in the case here) then you have a very very low probability of being preserved (let alone found and collected). Finally, even if these scenarios aren’t the case, there is the possibility that scientists have just been looking in the wrong strata, region, or age.

Upper Palaeolithic Beads of southern France

THE UPPER PALAEOLITHIC IS BEST UNDERSTOOD PERIOD OF THE OLD STONE AGE, BEGINNING SHORTLY AFTER THE EXTINCTION OF HOMO NEANDERTHALENSIS AND THE ENCROACHMENT OF THE NEW HOMININ HOMO SAPIENS FROM AFRICA INTO EUROPE.

The Upper Palaeolithic is marked by the dominance of artefacts, left behind by our ancestors. When compared to more recent times particularly to the advent of farming 10,000 years ago, evidence for how our Upper Palaeolithic ancestors lived and ordered their societies is very much lacking. Recently, questions are beginning to be raised about how we prejudge Upper Palaeolithic hominins.

Claire Heckel of the American Museum of Natural History, in association with the French National Centre for Scientific Research (CNRS) wants to harness the power of statistics and the archaeological record to understand the level societal complexity. Many decades ago, archaeologists assumed that early hunter-gatherers were simple people with simple societal structure. The rise of farming in the fertile crescent was argued to be a sharp contrast to what came before, with the sudden need to settle, develop states and thereafter kingdoms. Archaeologist today can’t entirely shed their idea of the contrast between the two moments in time. The question here is: Have we exaggerated the simplicity of Upper Palaeolithic hominins?

In order to begin to answer this question, we first need to find evidence of how Upper Palaeolithic society was structured. Heckel was very interested in what a tiny insignificant object like a bead could tell us about Upper Palaeolithic society. These Basket-shaped beads were found at four archaeological caves and rock shelters in Aquitaine, southern France. The beads are extremely interesting due to the projected time and effort needed to craft them. Some of the beads were made from steatite (soapstone), which is a talc-schist metamorphic rock, which got its name from the soapy feel of the talc in the rock. While others were crafted from mammoth ivory, broken into segments in a five-stage process.

The archaeological record has not always been very clear in shedding light on the past and so many anthropologists have appealed to ethnography to help explain what we see in the archaeological record. Many forget that what happens to the Kalahari Bushmen cannot count as a way of explaining the Upper Palaeolithic hominins of frozen Europe. The first archaeologists to try to use ethnography, was Dr. Lewis Binford who lived with the Nunamuit of Alaska as a way of peeking into life in Late Glacial Europe. This was flawed logic because it does not count as evidence and we need to return to the archaeological record to the direct clues. That is what Claire Heckel is doing here, by using morphometric analysis of 402 basket-shaped beads, the level of standardisation can be quantified.
Taking 6,432 data points on the 402 basket-shaped beads, Heckel used Analysis of Variance (ANOVA) to compare and contrast the shape and form of the beads from 4 cave and rock shelter sites. The results suggested that bead production was a highly standardised process and the statistical analyses were compared to those of Neolithic and Bronze age archaeological sites throughout the world, the level of mastery was comparable to the bead production specialisation during the advent of farming. There has been some debate as to how we should describe craft work in the Upper Palaeolithic.

For example, Jacques Pelegrin argued in 2007, that the word Mastery should be used to describe intensive craft work in the Upper Palaeolithic, while the word specialisation should be used to describe intensive craft work in the Neolithic. This debate continues today but however you phrase it, there is exchange taking place in the region of Aquitaine, southern France. Exposures of Steatite are easily identifiable compared to mammoth ivory, part of a biological organism that roamed the landscape. We can gauge the distance the steatite travelled from the source to the cave or rock shelter sites, an impossible task to overcome when it comes to ivory.

Heckel proposed three different models to explain the archaeological record in Aquitaine. Model 1 suggested that there was a single point in the region, where these beads were produced and distributed from there. Model 3 suggested that the Upper Palaeolithic nomadic groups crafted the beads at the four caves sites. But it was Model 2 that best fitted the above statistical analyses, suggesting that there were multiple territories with their own individual centre of production, while exchange and distribution resulted in the deposition at the cave and rock shelter sites. Heckel’s work is only the beginning of a long research process to see if we have exaggerated the simplicity of Upper Palaeolithic societal structure. Based on the basket-shaped beads found at the early Aurignacian archaeological sites, a small group of people appear to be spending a great deal of time crafting these beautiful objects.

Reprint from Heritage Daily

 

Skulls reveals that ancient Americans didn’t mix with neighbours

It’s a real head-scratcher. The shapes of human skulls from a narrow strip in Mexico reveal that first arrivals to the Americas may have kept to themselves, even when there were no geographical barriers that would have prevented them mixing.

Genetic studies have begun to unravel the complex story of the earliest American settlers, but archaeological studies can provide important details too – particularly the careful study of human skull shape. This is influenced by someone’s genetic history: when two populations become isolated from each other and can no longer interbreed, they each begin to develop unique genetic signatures – and skull shapes.

Mark Hubbe and Brianne Herrera at the Ohio State University in Columbus and their colleagues took detailed measurements from a series of 800 to 500-year-old skulls unearthed in three regions of Mexico. They then looked at equivalent measurements from skulls found at a number of sites across North and South America, East Asia and Australasia and analysed how skull shape varied with location.

Skulls from two of the Mexican regions – Sonora and Tlanepantla – clustered together in the shape analysis. But skulls from the third region, Michoacán, were different. The variation was on a scale normally seen between two populations that have been separated for millennia, often because they have settled in regions that are thousands of kilometres apart. Yet the distance between Michoacán and Tlanepantla is under 300 kilometres.

It’s an astonishing discovery, says Hubbe. Mexico was first inhabited at least 10,000 years ago, and the founding populations may well have had different genetic histories before they settled in the area. Crucially, the populations seem to have been so reluctant to interbreed that those genetic differences were still apparent just 500 years ago. “For whatever reason, these differences have been maintained for thousands of years,” says Hubbe.

Mexico lacks obvious geographical features that could have kept people apart – but formidable cultural and language barriers might have existed, says Hubbe.

“When it comes to population history, a whole host of scenarios are possible,” says Noreen von Cramon-Taubadel of the University at Buffalo, New York. “We see instances even in modern populations where neighbouring groups live in close geographic contact yet do not mix extensively in terms of marriage.”

Skull and other remains at Brazilian burial site

Hubbe and von Cramon-Taubadel collaborated on a second study, which involved analysing another set of early American skulls (pictured top and above). These came from Lagoa Santa in eastern Brazil and date back 10,000 to 7000 years, not long after South America was first inhabited.

“The Lagoa Santa material is unique in the entire New World,” says André Strauss at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who was also involved in the work. “It presents abundant, well-preserved, old skeletons with reliable associated archaeological context.”

The researchers discovered that these earliest South Americans – the “Palaeoamericans” – had skull shapes that are distinctly different from those of most indigenous South American populations alive today.

“The differences between the Palaeoamericans and today’s South Americans are so large that they cannot simply have appeared in 10,000 years,” says Hubbe.

In other words, the Palaeoamericans cannot simply have evolved into today’s indigenous South Americans. Instead, the researchers estimate that the two populations split apart from a shared ancestral population at least 20,000 years ago, offering a much larger time window for the two groups to develop distinct skull features.

Because the consensus is that the Americas were not inhabited 20,000 years ago, this conclusion implies that South America may have been colonised in at least two distinct waves – one represented by the ancient people at Lagoa Santa and another by today’s indigenous South American populations.

This goes against the general assumption that South America was initially colonised in just one wave, before the Europeans arrived. It isn’t the first evidence that the South American story is more complicated, though – a 2015 study also raised the possibility of multiple colonisation waves by uncovering a genetic link between some of today’s Amazonian populations and indigenous groups in Australia.

“It is great to see this new analysis of morphological data,” says Pontus Skoglund at Harvard Medical School, an author on the 2015 study. “It reiterates that there is something interesting about the peopling of the Americas that we don’t quite understand yet.”

Journal reference: American Journal of Physical Anthropology, DOI: 10.1002/ajpa.23186

Journal reference: Science Advances, DOI: 10.1126/sciadv.1602289

Article Reprint from New Scientist

How forensic science can unlock the mysteries of human evolution

image-20161220-26741-nuu3lc.JPG

People are fascinated by the use of forensic science to solve crimes. Any science can be forensic when used in the criminal and civil justice system – biology, genetics and chemistry have been applied in this way. Now something rather special is happening: the scientific skill sets developed while investigating crime scenes, homicides and mass fatalities are being put to use outside the courtroom. Forensic anthropology is one field where this is happening.

Loosely defined, forensic anthropology is the analysis of human remains for the purpose of establishing identity in both living and dead individuals. In the case of the dead this often focuses on analyses of the skeleton. But any and all parts of the physical body can be analysed. The forensic anthropologist is an expert at assessing biological sex, age at death, living height and ancestral affinity from the skeleton.

Our newest research has extended forensic science’s reach from the present into prehistory. In the study, published in the Journal of Archaeological Science, we applied common forensic anthropology techniques to investigate the biological sex of artists who lived long before the invention of the written word.

We specifically focused on those who produced a type of art known as a hand stencil. We applied forensic biometrics to produce statistically robust results which, we hope, will offset some of the problems archaeological researchers have encountered in dealing with this ancient art form.

Sexing rock art

Ancient hand stencils were made by blowing, spitting or stippling pigment onto a hand while it was held against a rock surface. This left a negative impression on the rock in the shape of the hand.

Experimental production of a hand stencil. Jason Hall, University of Liverpool

These stencils are frequently found alongside pictorial cave art created during a period known as the Upper Palaeolithic, which started roughly 40 000 years ago.

Archaeologists have long been interested in such art. The presence of a human hand creates a direct, physical connection with an artist who lived millennia ago. Archaeologists have often focused on who made the art – not the individual’s identity, but whether the artist was male or female.

Until now, researchers have focused on studying hand size and finger length to address the artist’s sex. The size and shape of the hand is influenced by biological sex as sex hormones determine the relative length of fingers during development, known as 2D:4D ratios.

But many ratio-based studies applied to rock art have generally been difficult to replicate. They’ve often produced conflicting results. The problem with focusing on hand size and finger length is that two differently shaped hands can have identical linear dimensions and ratios.

To overcome this we adopted an approach based on forensic biometric principles. This promises to be both more statistically robust and more open to replication between researchers in different parts of the world.

The study used a branch of statistics called Geometric Morphometric Methods. The underpinnings of this discipline date back to the early 20th century. More recently computing and digital technology have allowed scientists to capture objects in 2D and 3D before extracting shape and size differences within a common spatial framework.

In our study we used experimentally produced stencils from 132 volunteers. The stencils were digitised and 19 anatomical landmarks were applied to each image. These correspond to features on the fingers and palms which are the same between individuals, as depicted in figure 2. This produced a matrix of x-y coordinates of each hand, which represented the shape of each hand as the equivalent of a map reference system.

Figure 2. Geometric morphometric landmarks applied to an experimentally produced hand stencil. This shows the 19 geometric landmarks applied to a hand. Emma Nelson, University of Liverpool

We used a technique called Procrustes superimposition to move and translate each hand outline into the same spatial framework and scale them against each other. This made the difference between individuals and sexes objectively apparent.

Procrustes also allowed us to treat shape and size as discrete entities, analysing them either independently or together. Then we applied discriminant statistics to investigate which component of hand form could best be used to assess whether an outline was from a male or a female. After discrimination we were able to predict the sex of the hand in 83% of cases using a size proxy, but with over 90% accuracy when size and shape of the hand were combined.

An analysis called Partial Least Squares was used to treat the hand as discrete anatomical units; that is, palm and fingers independently. Rather surprisingly the shape of the palm was a much better indicator of the sex of the hand than the fingers. This goes counter to received wisdom.

This would allow us to predict sex in hand stencils which have missing digits – a common issue in Palaeolithic rock art – where whole or part fingers are often missing or obscured.

Palaeo-forensics

This study adds to the body of research that has already used forensic science to understand prehistory. Beyond rock art, forensic anthropology is helping to develop the emergent field of palaeo-forensics: the application of forensic analyses into the deep past.

For instance, we have been able to understand fatal falls in Australopithecus sediba from Malapa and primitive mortuary practices in the species Homo naledi from Rising Star Cave, both in South Africa.

All of this shows the synergy that arises when the palaeo, archaeological and forensic sciences are brought together to advance humans’ understanding of the past.

The above article was reprinted from The Conversation

What about insects in hominin diets?

For those fans of human evolutionary research news, you will be well aware of the lack of research into the role insects played in the diet of hominins over the past 6 or so million years.

Image

An Ant! – Credit: Wiki Commons

This topic was addressed back in 2001 in the chapter of an academic volume by William McGrew of the department of Archaeology and Anthropology, University of Cambridge. Since then nothing has been done to address ways in which such an investigation could be conducted. What can be done to address this? Look at what we………..modern primate diets and the role insects play in their diets from the human to the Orang-utan. Let’s then look at the earliest evidence for hominin consumption of insects. South Africa has nabbed that prize, thus far. The Lower Palaeolithic sites of Swartkrans, Sterkfontein and Drimolen contained hominin fossil bone tools with wear patterns similar to those wear patterns you find on sticks used by Chimps to fish for termites. Fossil remains of Paranthropus robustus were found at these sites and the evidence suggests they were feasting on termites.

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Paranthropus boisei (Extinct cousin of Paranthropus robustus) – Credit: Wiki Commons

Examining the fossil evidence is one focus, but there are others including, lithics, residues, dental microwear, stable isotopes, DNA and coprolites (Fossilised shit…..basically). The dental microwear is quite problematic, because you have to take note that the tooth has been in the earth for millions of years (2.4 million years for the earliest Paranthropus specimen). Stable isotopic research is the much more promising of the topics discussed in William McGrew’s latest paper for the Journal of Human Evolution.

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