Anthropology.net

In this paper by Ruggero D’Anastasi and his colleagues, they show how lesions in the fossilised lumbar vertebrae of Australopithecus africanus Stw 431 from Sterkfontein, South Africa may have been caused by the individual’s consumption of meat during its lifetime, prompting the researchers to ask to what extent australopithecines living between 2.4 million and 2.8 million years BP may have included meat in their diet.

Abstract:

We report on the paleopathological analysis of the partial skeleton of the late Pliocene hominin species Australopithecus africanus Stw 431 from Sterkfontein, South Africa. A previous study noted the presence of lesions on vertebral bodies diagnosed as spondylosis deformans due to trauma. Instead, we suggest that these lesions are pathological changes due to the initial phases of an infectious disease, brucellosis. The macroscopic, microscopic and radiological appearance of the lytic lesions of the lumbar vertebrae is consistent with brucellosis. The hypothesis of brucellosis (most often associated with the consumption of animal proteins) in a 2.4 to 2.8 million year old hominid has a host of important implications for human evolution.

The consumption of meat has been regarded an important factor in supporting, directing or altering human evolution. Perhaps the earliest (up to 2.5 million years ago) paleontological evidence for meat eating consists of cut marks on animal remains and stone tools that could have made these marks. Now with the hypothesis of brucellosis in A. africanus, we may have evidence of occasional meat eating directly linked to a fossil hominin.

As is noted in the freely accessible paper, brucellosis is sometimes associated in modern populations with the consumption of of dairy products and unpasteurised cheese, but can also be passed on through infected meat. The lesions in the vertebrae ostensibly also conform to spondylosis caused by traumatic injury, but upon close examination we see:

A preliminary examination revealed the presence of some pathological lesions on the vertebral bodies. Lumbar vertebrae L4 and L5 have lytic lesions on the superior-anterior margin of the vertebral bodies; in particular L5 showed an excavation of the anterior-superior body with osteophytes. The position and gross morphology of the lesions were very similar to the pathological bone alterations observed in some infectious diseases in modern humans, such as in human zoonotic brucellosis [15].

The researchers postulate that this may be the oldest yet known, albeit indirect evidence that A. africanus may have included meat in their diet, and because carnivorous activity has also been observed in baboons and chimpanzees, it doesn’t seem unreasonable to suggest that predecessors of Homo may also have eaten meat. Meat consumption is suggested to have have played a significant role in human evolution, but it has yet to be confirmed when our ancestors began eating meat in sufficient quantities for evolution to have been affected, or indeed exactly the effects would have been.

Reference: D’Anastasio R, Zipfel B, Moggi-Cecchi J, Stanyon R, Capasso L (2009) Possible Brucellosis in an Early Hominin Skeleton from Sterkfontein, South Africa. PLoS ONE 4(7): e6439. doi:10.1371/journal.pone.0006439

Carl Feagans is hosting a birthday edition of the carnival over at his blog A Hot Cup of Joe, number 72 to be precise, so grab a party hat and head on over to check out the latest compilation of anthropology blogging over the last couple of weeks, including the abstract to a paper asking whether language confers other cognitive abilities in humans. Many thanks (and best wishes) to Carl for taking time out on his birthday to post this edition, and next time round Greg Laden will be the host, when 4SH returns on August 12th.

Please send submissions for 4SH 73 here, and to the same location if you’d like to host your own edition in the future, the next available window for which is September 9th.

Here’s the introduction to a paper which seeks to determine when and for what reasons modern human populations began to undergo rapid growth spurts at various times during the Late Pleistocene and on into the Neolithic:

Reconstructing the timing and magnitude of changes in human population size is important for understanding the impact of climatic fluctuation, technological innovation, natural selection, and random processes in the evolution of our species. With census population sizes estimated to be only in the millions during most of the Pleistocene [1], [2], it is obvious that human population size has increased dramatically towards the present.

A major unanswered question is whether expansion began with hunter-gatherer groups, perhaps as a result of the invention of particular technologies or behavioral innovations, or much more recently with the advent of agriculture [3]. Early mtDNA studies suggested that humans experienced a burst of population growth between 30 and 130 thousand years ago (kya)—well before the start of agriculture [4]. More recent results have extended the timeframe for sub-Saharan African growth to 213–12 kya, depending in part on mtDNA haplogroup [5], [6].

However, it is populations—not haplogroups—that are subject to growth, and many present-day hunter-gatherer groups, including those in Africa, do not exhibit any mtDNA signal of demographic expansion at all [7]. On the other hand, Y chromosome sequence data are compatible with a model of constant size for both hunter-gatherer and farming populations in Africa [8]. Autosomal microsatellites tend to indicate an early (pre-Neolithic) start to population growth, but there is disagreement among studies on the time of expansion and whether or not the expansions involved African populations [9], [10]. Zhivotovsky et al. [11] examined a large autosomal microsatellite dataset in 52 worldwide populations and concluded that African farmers, but not hunter-gatherers, exhibit the signal of population growth.

Unfortunately, inferences of demographic parameters based on the above mentioned loci may be unreliable due to the possible confounding effects of natural selection or evolutionary stochasticity (for the haploid loci), or uncertainty in our understanding of mutation rates or the underlying mutation process (for mtDNA and microsatellites) [1], [3].

As this is published at PLoS ONE, the entire paper and supplementary materials are free to access, and readers are accordingly encouraged to spread the word, as advised by Coturnix at A Blog Around the Clock:

As always, you should rate the articles, post notes and comments and send trackbacks when you blog about the papers. You can now also easily place articles on various social services (CiteULike, Mendeley, Connotea, Stumbleupon, Facebook and Digg) with just one click.

Moreover, there are many articles published each week covering a wide array of scientific research, as can be seen by regular updates at the same blog, which are aptly named ‘New and Exciting in PLoS ONE’ , and generally appear at least once a week.

Reference: Autosomal Resequence Data Reveal Late Stone Age Signals of Population Expansion in Sub-Saharan African Foraging and Farming Populations – PLoS ONE

Cox MP,  Morales DA,  Woerner AE,  Sozanski J,  Wall JD,  et al. 2009 Autosomal Resequence Data Reveal Late Stone Age Signals of Population Expansion in Sub-Saharan African Foraging and Farming Populations. PLoS ONE 4(7): e6366. doi:10.1371/journal.pone.0006366

Just a very brief news item from Atapuerca in northern Spain, where recent excavations by team leaders Juan Luis Arsuaga and Ignacio Martínez working in Sima de los Huesos, have turned up some pretty impressive cranial material from H.heidelbergensis, dating back 500,000 years, a discovery which follows on from the 1.3 million year old partial humerus find in the Sima del Elefante, earlier in the year. (PDF)

Unlike the earlier discovery, and judging by the photo, there don’t appear to be any obvious butchery or cut marks on the latest skull fragments to be found, signs which in the past have been interpreted to mean that cannibalism was taking place at the site over many hundreds of years by different resident species of archaic humans.

Thus far, Neanderthals are the only archaic human species not to have been found at Atapuerca, but according to the linked article at El Mundo, there are hopes that clues to a Neanderthal presence may yet be detected in the Galería de las Estatuas, where ‘animal fossils and stone tools’ have been found – there is no description or dating as yet, but my guess would be that the archaeologists are hinting that the stone tools bear the hallmarks of Mousterian lithic culture.

(via Mundo Neandertal)

image: Skull 17, Sima de los Huesos from El Mundo, Javier Trueba

Back in May 2009, Science Debate and the New York Academy of Science collaborated in putting together a conference by the name of ‘A Dangerous Divide: The Two Cultures in the 21st Century’, which is described at the linked website as follows:

On May 9, 2009, the New York Academy of Sciences’ Science & the City program hosted a daylong symposium in honor of the 50th anniversary of C.P. Snow’s influential lecture on the “two cultures.” Whereas Snow focused on a gap of understanding between scientists and literary intellectuals, speakers at the Academy spotlighted a troubling gulf between the scientific community today and the general public. Because science and technology are critical tools for responding to many of society’s most troubling problems, participants argued that this lack of understanding is having dangerous consequences.

Panellists at the symposium focused on the historical context of the two cultures divide, barriers to effective science communication, ways in which lack of public understanding of science is affecting politics, and ways to improve science education and science citizenship. Topics discussed included challenges in making science relevant to nonscientists, institutional pressures that are making good science journalism more difficult, practical ways to engage politicians on scientific issues, and recommendations for ways to improve science education and public understanding of science. Speakers stressed that professional scientists have an important role to play in explaining what they do and why it should be important to those outside the scientific community.

Further down on the same page is are notes describing each of the presentations that are now available to watch free online,  which can be accessed by hitting the ‘media’ tab at the top of the page, or indeed by clicking this link.

So far I’ve only had time to watch one entire presentation, that being ‘Science Communication‘ which features guest speakers Robert Keating (Discover magazine), Paula Apsell (NOVA, WGBH), Ira Flatow (NPR Science Friday), Andrew Revkin (The New York Times/Dot Earth), Carl Zimmer (Science Writer/The Loom).

This talk, including questions from the audience, lasts almost exactly one hour, and addresses the ongoing problems of how science can better communicate with the general public, through various media such as broadcast news, the printed Press (comprising newspapers and magazines), TV documentaries, and of course, the blogosphere.

Rather than analyse the entire presentation, or the ways in which science writers need to be given far more scope and opportunity to communicate with the general public, I’m just going to zero in on one area and add a brief thought or two on how TV science documentaries could and should reach a far greater audience. With the increasing reliance of the public on online resources to source science news and debate, it seems clear that much more effort needs to be made in ensuring that as many science documentaries as possible should be made available online, rather than being mostly restricted to the TV.

We live in a digital age whereby tens, if not hundreds of millions of people worldwide have access to high speed internet, the ideal medium for broadcasting documentaries in their entirety, and at resolutions high enough to compete with a TV. Yet finding much in the way of in-depth and informative science documentaries online is difficult, largely because of the way in which the TV industry is regulated, but mostly because of the stranglehold that advertisers have. Although TV has the outward appearance of being a medium which shows programmes interspersed with adverts, the opposite is actually true – the programmes are merely filler between those adverts.

So despite the fact that many of the TV documentary channels have excellent websites, the potential viewer can only see brief teasers of a few minutes’ duration at most, forcing the viewer to move from the computer to the TV – as long as they happen to live in the same country in which the show is being presented. There is no way for someone in a different country to visit a website, pay a couple of bucks/ or agree to have ads included, and watch the documentary of their choice online, there and then.

Which most often means that viewers outside the US have no access to science documentaries until or unless the shows are syndicated out across the world at a later date – meaning that a potentially vast audience will miss out on some of the best science communication on offer. A similar situation exists in Britain, where the BBC have a long history of producing outstanding documentaries – which can only be seen by TV license holders residing in the UK. This again means that only a very small percentage of potentially interested viewers will get to see up-to date and ground-breaking research portrayed in documentaries, all because of out-dated and out-moded ideas which hold that most TV content of quality should only be available on a regional basis.

So my generalistic suggestions would be for the TV advertisers and their client companies to wake up and get with the real world – literally and metaphorically, by plugging into the internet. They should be showing exactly the same TV content (including their dreary ads which could be tailored on a regional or national basis as required), or allowing for online subscription to documentary channels so that people like me in Europe would be able to access sources such as NOVA, Discovery, National Geographic Channel etc, while US residents would be able to access documentaries from the BBC, Channel 4 and others.

Although that’s a solution heavily biased towards English speakers living in the West, there are already ways of making such content understandable to speakers of other languages – in Europe for example where many US shows are broadcast with a dubbed local language, there are remote controls which allow the viewer to switch to another language, a technology which should in the future be enhanced to include more languages and be available for online TV abroad.

This wouldn’t work for all TV content of course, but as far as the dissemination of science and trying to solve problems such as energy alternatives and global warming is concerned, the more access the global public has to well made and informative TV documentaries, the greater the chances of spreading the word and finding solutions, especially at local levels. It’s clear we cannot rely on governments alone for good advice or guidance, but clear and coherent education in the guise of unbiased documentaries might go a long way towards allowing the public to circumnavigate selfish and exploitative regimes who would prefer to keep themselves in office by restricting what we know and how we come to know it.

Moreover it would be extremely interesting for western viewers to be able to access science documentaries made in places like Africa, India and Asia, where again, we might get to see documentaries detailing the effects climate change is having in those regions and what ideas and initiatives are  being undertaken by people there.

In fact I have little doubt that in 20 or 30 years’ time this technology will be c0mmonplace, but I don’t think we should be waiting that long – there are very many serious problems which need addressing right now, and it would be far better for us all to have a global audience acquainted with science, and the ways in which it can and must be used to help solve those problems, rather than a few select target audiences here in the West. As is noted in the presentation, not all the public are going to suddenly start reading PLoS or PubMed every day, but there is nevertheless a a great deal of public interest in science and how it affects our lives and surroundings, now and into the future. This is partly evidenced by the fact that science podcasts at iTunes are in high demand and accordingly downloaded in their millions, but for reasons that are not understood, advertisers have thus far shown no interest in utilising such a resource.

iTunes currently makes little effort to include science documentaries in their visual content available for purchase – there are some very good series available like ‘South Pacific’ as well as most of the David Attenborough collection, and the ‘Walking With Monsters’/'Beasts’/'Cavemen’ series, (all BBC productions), but precious little besides, Apple preferring instead to concentrate on popular entertainment. However, they do at least provide plenty of  free audio content with iTunes U, and that at least is a major step in the right direction.

I’m not sure when I’m going to be able to watch or review the other videos online at NYAS, but they should all be of interest to readers here, as should the website Science Debate, run by Shawn Otto – it was Science Debate 2008 which prompted the two presidential candidates to address science in their campaigns, and to find out how Obama and McCain responded to a set of 14 questions, plus a ton of other information, a visit to the site is advised.

image: from another Two Cultures event copyright (another) Tim Jones, Zoonomian blog.

The 72nd edition of the Four Stone Hearth anthropology blog carnival is due to appear this coming Wednesday, July 29th, and will be hosted by Carl over at A Hot Cup of Joe – so if you’ve recently written something of your own, or seen a post on another blog you deem worthy of consideration and inclusion, please send it along to the host in plenty of time.

Although this is described as a provisional paper, and therefore subject to alteration before official publication, it’s published in full as a provisional pdf, in which it is proposed that the genetic footprints of Australia’s first inhabitants, estimated to have arrived around 45,000 years BP, can be detected in modern-day Indian populations. The main points covered in the paper are as follows:

Background:  An early dispersal of biologically and behaviorally modern humans from their African origins to Australia, by at least 45 thousand years via southern Asia has been suggested by studies based on morphology, archaeology and genetics. However, mtDNA lineages sampled so far from south Asia, eastern Asia and Australasia show non-overlapping distributions of haplogroups within pan Eurasian M and N macrohaplogroups. Likewise, support from the archaeology is still ambiguous.

Results:  In our completely sequenced 966-mitochondrial genomes from 26 relic tribes of India, we have identified seven genomes, which share two synonymous polymorphisms with the M42 haplogroup, which is specific to Australian Aborigines.

Conclusions  Our results showing a shared mtDNA lineage between Indians and Australian Aborigines provides direct genetic evidence of an early colonization of Australia through south Asia, following the “southern route”.

Reference: Reconstructing Indian-Australian Phylogenetic Link by Satish Kumar, Rajasekhara REDDY Ravuri, Padmaja Koneru, B P Urade, B N Sarkar, A Chandrasekar and V R Rao.

BMC Evolutionary Biology 2009, 9:173 doi:10.1186/1471-2148-9-173

Here’s another free to access paper, by Robert Dunn et al, which discusses circumstances under which extinctions can occur,  how extinction of one species leads to others, and how extinction dynamics can be assessed and used to predict similar events in the future, when coextinction rates are predicted to increase.

This is the abstract:

The effects of species declines and extinction on biotic interactions remain poorly understood. The loss of a species is expected to result in the loss of other species that depend on it (coextinction), leading to cascading effects across trophic levels. Such effects are likely to be most severe in mutualistic and parasitic interactions. Indeed, models suggest that coextinction may be the most common form of biodiversity loss. Paradoxically, few historical or contemporary coextinction events have actually been recorded. We review the current knowledge of coextinction by: (i) considering plausible explanations for the discrepancy between predicted and observed coextinction rates; (ii) exploring the potential consequences of coextinctions; (iii) discussing the interactions and synergies between coextinction and other drivers of species loss, particularly climate change; and (iv) suggesting the way forward for understanding the phenomenon of coextinction, which may well be the most insidious threat to global biodiversity.

Reference: The Sixth Mass Coextinction: Are Most Endangered Species Parasites and Mutualists? by Robert R. Dunn, Nyeema C. Harris, Robert K. Colwell, Lian Pin Koh, Navjot S. Sodhi

Published online before print May 27, 2009, doi: 10.1098/rspb.2009.0413 Proc. R. Soc. B 7 September 2009 vol. 276 no. 1670 3037-3045

Here’s a freely accessible paper which amongst many considerations, discusses genetic diffusion in pastoral human populations at the Neolithic transition, and why Lactose Persistence, or specifically lactase persistence allele(s) (LCT*P),  which allows for the digestion of fresh milk, was strongly selected for in northern Europe, at the start of agricultural domestication. This is the introduction:

Lactase is an enzyme that allows lactose digestion in fresh milk. Its activity strongly decreases after the weaning phase in most humans. However, in many European individuals and in people from various populations of other continents, lactase is still active throughout adult life [1]. This dominantly inherited genetic trait is called lactase persistence and at least three mutations are tightly associated with it: −13,910 C/T (generally linked to −22,018 G/A) in northern Europe (100% association) [2], [3], −14,010 G/C in East Africa and −13,915 T/G in the Middle-East/North Africa [4], [5]. In this study, we will use LP to refer to the lactase persistence phenotype, LCT to refer to the lactase gene and LCT*P to refer to the lactase persistence associated allele(s).

The particular distribution of lactase persistence throughout the world indicates that this trait evolved under strong positive selection [5], [6], [7]. Two main hypotheses have been proposed: gene-culture coevolution (gcc) [8], [9], which suggests that lactose digestion confers a nutritional advantage to milk-consuming (e.g. pastoralist) populations; and calcium assimilation (cal) [10], which proposes that carriers of LCT*P are favoured in high-latitude regions, where lactose would substitute vitamin-D (deficient when sunlight is low) to allow accurate calcium assimilation, thus preventing rickets. Holden and Mace [11] studied the two mentioned hypotheses and a third one, proposing that LP was favoured in highly arid environments, where people would have drunk milk to prevent dehydration [12], [13]. Their conclusion was that LP is an adaptation to pastoralism, in agreement with the gcc model, while no evidence for the other hypotheses was found. Compatible with this theory, Coelho et al. [14] suggested that −13,910*T originated in Eurasia before the Neolithic Era, and observed a significant departure from neutrality of this variant in the few populations examined. On the other hand, these studies do not explain the significant correlation found between LP frequencies and latitude in Europe [15], as predicted by the cal model.

Reference: Selection and Demography on the Diffusion of Lactase Persistence

Gerbault P, Moret C, Currat M, Sanchez-Mazas A, 2009 Impact of Selection and Demography on the Diffusion of Lactase Persistence. PLoS ONE 4(7): e6369. doi:10.1371/journal.pone.0006369

See also: Science Daily – Longer Life For Milk Drinkers, Study Suggests

There’s been lots of interesting anthro news this past week which as yet I haven’t had the time to write up, and it might be a day or two yet before I catch up. In the meantime I hope readers will find this freely accessible paper of interest, which investigates the remarkable way in which leatherback turtles, amongst others, are able to return to specific geographical locations many years after their prior visit. Although this phenomena has long been observed, nobody as yet has been able to determine the processes and navigational capabilities by which turtles are able to achieve these feats. It has taken humans hundreds if not thousands of years to be able to navigate with confidence around the world’s vast oceanic spaces, and yet the turtle appears to have an inbuilt capacity for long distance navigation over many years without recourse to invented technologies.  This paper examines ocean currents, magnetic cues and visual clues, in an attempt to unravel the mystery of the ocean-going turtle.

Abstract:

The open-sea movements of marine animals are affected by the drifting action of currents that, if not compensated for, can produce non-negligible deviations from the correct route towards a given target. Marine turtles are paradigmatic skilful oceanic navigators that are able to reach remote goals at the end of long-distance migrations, apparently overcoming current drift effects. Particularly relevant is the case of leatherback turtles (Dermochelys coriacea), which spend entire years in the ocean, wandering in search of planktonic prey. Recent analyses have revealed how the movements of satellite-tracked leatherbacks in the Indian, Atlantic and Pacific Oceans are strongly dependent on the oceanic currents, up to the point that turtles are often passively transported over long distances.

However, leatherbacks are known to return to specific areas to breed every 2–3 years, thus finding their way back home after long periods in the oceanic environment. Here we examine the navigational consequences of the leatherbacks’ close association with currents and discuss how the combined reliance on mechanisms of map-based navigation and local orientation cues close to the target may allow leatherbacks to accomplish the difficult task of returning to specific sites after years spent wandering in a moving medium.

It is suggested that some turtles showed an ability to respond to the Earth’s magnetic field, and that this ability was compromised in some turtles who had small magnets attached to their heads by researchers; an interesting paper which suggests that in addition to the proposed factors prevalent in the turtles’ abilities to achieve long term navigational goals, other elements also play a part.

An olfactory factor might be present as described in this abstract, and note is also made of the sun, moon and stars as other possible factors present in aiding turtle navigation; in the linked paper we learn that turtles have been tracked on their voyages by satellites in space, a technology developed by humans only made possible in the last few hundred years as we began to appreciate the movements and dynamics of our own solar system. Whether turtles have a map of the skies and are able to chart the relative positions of moving objects therein, isn’t covered in this study, but such an awareness is surely a potential contender for explaining how turtles are able to keep track of their global positioning status at all times.

Reference: Navigational Challenges in the Oceanic Migrations of Leatherback Sea Turtles by Alessandro Sale and Paolo Lusch

Published online before print July 22, 2009, doi: 10.1098/rspb.2009.0965 rspb20090965

image: Leatherback turtle from ‘Why would a Leatherback Turtle Dive 1000m Deep?’ at Deep Sea News