Tuesday, 28 December 2010

How Neanderthals cooked their food

But the Neanderthals were also capable of harvesting and processing plant foods. In a study published in the US journal PNAS, calculus was removed from the teeth of three Neanderthal individuals: Shanidar III from Shanidar Cave, Iraq and Spy I and Spy II from Spy Cave, Belgium. Shanidar III yielded a large number starch grains, some of which were identified as originating from the Triticeae tribe of grasses, which includes the wild relatives of wheat, barley and rye. Others were from legumes. Importantly, many of the grains had been cooked. Although less numerous than the starch grains, a number of phytoliths were also recovered. These are rigid microscopic bodies, composed of silica, that occur in many plants and serve a number of purposes, including lending the plant structural rigidity and making it distasteful to predators. The bulk of the phytoliths recovered from Shanidar III originated from date palms. Starch grains were also recovered from the two Spy Cave Neanderthals. Some were found to be from tubers, possibly of water lilies. Others were from grass seeds, possibly sorghum.

Although neither site has yielded evidence of stone artefacts specialized for use as grinding implements, or of storage features, there is clear evidence that at both sites Neanderthals were employing preparation techniques which increased the edibility and nutritional quality of plant foods, including husking and cooking of seeds. Date palms have different harvest seasons to barley and legumes, suggesting that the Shanidar Neanderthals practiced seasonal rounds of collecting and scheduled returns to harvest areas.

Anthropologists have long been interested in the timing of two major hominin dietary adaptations; the cooking of plant foods and an expansion in dietary breadth or “broad spectrum revolution”. This led to the incorporation of a diversity of plant foods such as grass and other seeds that are nutritionally rich but relatively costly to exploit. That the Neanderthals mastered both adaptations in two widely-separated climates – Mediterranean and northern oceanic – is further proof of their sophistication.

Henry, A., Brooks, A., & Piperno, D. (2010). Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets (Shanidar III, Iraq; Spy I and II, Belgium). PNAS , Early Edition, 1-6.

Thursday, 23 December 2010

Modern humans interbred with Denisovans

In 2008, a distal manual phalanx of from a hominin little finger was recovered from Denisova Cave in the Altai Mountains of southern Siberia. The cave is named for a hermit called Dionisij (Denis) who is supposed to have lived there in 18th Century, but if this is true he was only the latest in a long line of inhabitants.

In April 2010, a report was published in the journal Nature (Krause, et al., 2010) suggesting that the phalanx had belonged to a hitherto-unknown human species. The small bone was dated by stratigraphic methods and found to be in the region of 30,000 to 48,000 years old. It is believed to have belonged to a child aged between 5 and 7 years old, but other than that no morphological classification could be made. However, due to the cool, dry climate, it proved to be possible to extract DNA from the bone and isolate mtDNA fragments, from which it proved possible to sequence the entire mitochondrial genome. Because we inherit our mtDNA solely from our mothers, this led to the find being dubbed X Woman, despite being from a juvenile of then unknown gender.

At the time in question, Neanderthals, identified as such by their mtDNA, were living less than 100 km (60 miles) away. The presence of an Upper Palaeolithic industry at Siberian sites such as Kara-Bom and Denisova itself has been taken as evidence for the appearance of modern humans in the Altai before 40,000 years ago. The expectation, therefore, was that the mitochondrial DNA from the bone would match that of either Neanderthals or modern humans, but neither turned out to be the case. Instead, sequencing revealed that X Woman had last shared a common ancestor with Neanderthals and modern humans about a million years ago.

X Woman clearly wasn’t a Neanderthal or a modern human, but what was she (if indeed she was a “she”)? One possibility was Homo heidelbergensis, the presumptive common ancestor of the Neanderthals and modern humans. But Homo heidelbergensis appeared no earlier than 600,000 years ago – long after X Woman’s ancestors. On the other hand, the date of one million years was too late for X Woman to be a late-surviving descendant of the first wave of Homo erectus to reach the Far East.

Towards the end of 2010, a second report was released in Nature detailing the sequencing of X Woman’s nuclear genome (Reich, et al., 2010). It turned out that “X-Woman” lacked a Y-chromosome and therefore was indeed female. Also described in the same report was an upper molar tooth. The latter appeared to be from a young adult and also yielded mtDNA, which in turn confirmed that it belonged to a different individual to phalanx. For this reason, the term “X-Woman” was dropped in favour of “Denisovan”.

According to the report, both mitochondrial and nuclear genomes suggest that the Denisovans are more closely related to Neanderthals than they are to modern humans. The nuclear data suggested that the Denisovans diverged from Neanderthals 640,000 years ago and from present-day Africans 804,000 years ago, suggesting that Densovans and Neanderthals were sister groups, sharing a more recent common ancestor than modern humans and Neanderthals. Africans were used for the comparison to avoid the confounding effects of the interbreeding thought to have occurred between archaic humans (previously thought to be Neanderthals) and the first modern humans to leave Africa. It was also found that the archaic component of the modern Eurasian genome has closer affinities to Neanderthals than to Denisovans, confirming that the interbreeding did occur with the former rather than the latter.

The divergence data obtained from the nuclear DNA is rather at odds with that obtained from the mtDNA. The report suggested two possible causes; firstly interbreeding between Denisovans and as yet unknown hominins; secondly, that the Denisovans retained an archaic mitochondrial lineage that has been lost from Neanderthals and modern humans due to the effects of genetic drift. The latter explanation is the more parsimonious, but the report concluded that the two scenarios were equally likely according to the data.

The most remarkable finding was that 4.8 percent of the nuclear genome of present-day Papuans derives from Denisovans, greater than the Neanderthal contribution of 2.5 percent and meaning that uniquely for modern humans, the Papuans are more closely-related to Denisovans than they are to Neanderthals. Overall, the data was consistent with a scenario in which modern humans, on leaving Africa, interbred with Neanderthals and then, at some subsequent point, the ancestors of present-day Papuans interbred with Denisovans, but this did not affect any other non-African populations. The implication is that Denisovans were present in Southeast Asia as well as southern Siberia. This in turn raises the possibility that the archaic humans living in the Far East as recently as 27,000 years ago (Swisher, et al., 1996), conventionally described as late Homo erectus, may in fact be Denisovans.

The Denisova tooth, which is probably a third or possibly second left upper molar, is fairly large, within the size range occupied by Homo erectus and Homo habilis and larger than that typical of Neanderthals and early modern humans. But the report failed to note that some early modern human teeth are also very large, such as those associated with the 35,000 year old lower jawbone from Peştera cu Oase in Romania I) (Trinkaus, Milota, Rodrigo, Mircea, & Moldovan, 2003; Trinkaus, et al., 2003). Size alone probably does not tell us very much. That the tooth shares no derived morphological features with Neanderthals or modern humans further indicates the distinctiveness of the Denisovans; but it also lacks any features in common with the very few third upper molars that have been recovered from other late archaic hominins in the Far East. Thus the tooth fails to support a connection between the Denisovans and known archaic human fossil remains from the Far East.

Clearly there is a very interesting story here, but until further fossil and/or genetic evidence comes to light, there is nothing more definite that can be said at this stage.

Krause, J., Fu, Q., Good, J., Viola, B., Shunkov, M., Derevianko, A., et al. (2010). The complete mitochondrial DNA genome of an unknown hominin from southern Siberia. Nature , 464, 894-897.

Reich, D., Green, R., Kircher, M., Krause, J., Patterson, N., Durand, E., et al. (2010). Genetic history of an archaic hominin group from Denisova Cave in Siberia. Nature , 468, 1053-1060.

Swisher, C., Rink, W., Anton, S., Schwarcz, H., Curtis, G., Suprijo, A., et al. (1996). Latest Homo erectus of Java: Potential Contemporaneity with Homo sapiens in Southeast Asia . Science , 274, 1870 - 1874.

Trinkaus, E., Milota, S., Rodrigo, R., Mircea, G., & Moldovan, O. (2003). Early modern human cranial remains from the Pestera cu Oase, Romania. Journal of Human Evolution , 45, 245–253.

Trinkaus, E., Moldovan, O., Milota, Ş., Bîlgăr, A., Sarcina, L., Athreya, S., et al. (2003). An early modern human from Peştera cu Oase, Romania. PNAS , 100 (20), 11231–11236.

© Christopher Seddon 2010

Wednesday, 22 December 2010

Grim fate of Neanderthal family group, 49,000 years ago

Evidence has come to light of the grim fate of a Neanderthal family group that lived in Spain 49,000 years ago. After apparently enduring a lifetime of privation, they were killed and eaten by members of a neighbouring Neanderthal group – presumably themselves on the brink of starvation and thus driven to extremities.

In 1994, extensive human remains were found at El Sidrón, an extensive system of karstic limestone caves in the Asturias region of northern Spain. Systematic excavation commenced in 2000 and to date around 1800 hominin skeletal fragments and 400 Mousterian-type stone tools have been recovered. The latter include side scrapers, denticulate pieces, a hand axe, and several Levallois points. The human remains are thought to represent twelve Neanderthal individuals, including three adult males, three adult females, three male adolescents and two juveniles and an infant of unknown gender.

A group size of 12 individuals at El Sidron is reasonably consistent with a previous estimate of between 8 to 10 individuals per Neanderthal group, based on the size of sleeping and combustion activity areas in the long-occupied rock shelter of Abric Romaní, near Barcelona. However, because the original external deposit cannot be studied, it could not be rules out that the El Sidrón group was larger and that some original members are not represented among the remains.

The tools and remains were found in a side gallery deep within the cave complex, and was probably introduced into the cave from the surface when a violent storm caused an upper gallery or a series of fissures to collapse. Pebbles and clay were also dragged down from the surface. The whole assemblage is around 49,000 years old. Around 18 percent of the tools have been refitted, suggesting that they are all the same age and that the associated human remains represent all or part of a contemporaneous social group of Neanderthals, who died at around the same time.

The low temperature of the side gallery meant that genetic material has survived and mitochondrial DNA has been extracted from each of the individuals. It was found that all three of the adult males carried the same mitochondrial lineage, but the three adult females all carried different lineages. Mitochondrial DNA is not a part of the primary genome and is inherited solely from the maternal line. The implication, therefore, is that the males shared the same maternal lineages but the females all had different maternal lineages. This suggests that in Neanderthal groups, mature males remained within their family birth group, but females came from outside. Patrilocality, as it is known, is present in about 70 percent of modern human societies, where men remaining in the family home but women move to the home of their new husband upon marriage.

But there is a darker side to the discoveries. All the El Sidrón individuals suffered from developmental stress, or periods of growth arrest, presumably arising from malnutrition. This is indicated by deficiencies in dental enamel, present on over 50 percent of the group members’ incisors, canines and premolars and over 30 percent of their molars. Five of the members had experienced two such episodes of growth arrest and one adult had experienced four. It is clear that for this extended Neanderthal family, life was very difficult – and in the end, it seems, they met a grim fate.

Cut marks and breaks have been found on many of the bones, including lower jawbones, skulls and long bones; evidence of skinning activity and extraction of bone marrow and brains – in other words, cannibalism.

Lalueza-Foxa, C., Rosas, A., Estalrrich, A., Gigli, E., Campos, P., García-Tabernero, A., et al. (2010, December). Genetic evidence for patrilocal mating behavior among Neandertal groups. PNAS .

Rosas, A., Martınez-Maza, C., Bastira, M., Garcıa-Tabernero, A., Lalueza-Fox, C., Huguet, R., et al. (2006). Paleobiology and comparative morphology of a late Neandertal sample from El Sidron, Asturias, Spain. PNAS , 103 (51), 19266–19271.

Vallverdu, J., Vaquero, M., Caceres, I., Allue, E., Rosell, J., Saladie, P., et al. (2010). Sleeping Activity Area within the Site Structure of Archaic Human Groups Evidence from Abric Romanı Level N Combustion Activity Areas. Current Anthropology , 51 (1), 137-145.

© Christopher Seddon 2010

Thursday, 25 November 2010

Whatever happened to "the customer is always right"?

If you are running a shop, it always used to be a rule that you should give the customer what they want. Not any more it seems. Increasingly, presumptuous managers are coming round the the idea that THEY know best.

Until recently, I used to have a couple of fresh-baked poppy-seed rolls or ciabattas from my local Sainsburys for lunch. Notably these two types were easily the most popular types, and often sold out. I was therefore completely mystified and a little put out when, shortly before Christmas last year, the store stopped selling poppy seed rolls and then, to compound the felony, discontinued the ciabattas a few months later. As both types remained on sale elsewhere, I assumed that this was the result of some kind of mixup, but after months of correspondance had failed to resolve the situation, I finally got to the bottom of the matter - "This is based on our policy to provide a wide and varied range of products and to offer our customers the opportunity to try something different."

Excuse me, I'll decide when and if I want to "try something different". For my part, I "tried" shopping at Waitrose instead of Sainsburys, which is "different" but probably wasn't the intended consequence of this policy. Unfortunately, Sainsburys are not the only offender. The sandwhich chain Pret a Manger is virtually synonymous with its All Day Breakfast - a bacon, sausage, egg and tomato sandwhich which is even described as "famous" on their website. Except try finding an outlet that actually sells it. If you live in Glasgow or Liverpool, you are fresh out of luck - "None of our shops in Glasgow or Liverpool sell this sandwich" I was informed, after frustrating experiences in both these places. The situation in London is little better; earlier this week I gave up in disgust after trying no fewer than four outlets.

The explanation: "This sandwich is one that Managers can choose whether to sell or not in their shops dependent on sales and customer demand." Right, once again, the manager knows best. If you are nursing a hangover in Glasgow or Liverpool - hardly an infrequent occurrence - you'll have to make do with some ghastly rabbit-food special and tell yourself it it so much better for you than the all-day breakfast you'd dragged yourself out of bed for.

© Christopher Seddon 2010

Saturday, 16 October 2010

MS Queen Victoria in Istanbul

Launched in 2007, the Cunarder MS Queen Victoria and her sister ship MS Queen Elizabeth are twice the size of the Titanic and significantly larger than the original RMS Queen Mary and RMS Queen Elizabeth and the legendary French SS Normandie.

Tied up alongside the Istanbul Modern art gallery, the sheer size of the ship is apparent in this photograph.

The Victoria is a modified Vista class cruise ship. Unlike her even bigger sister RMS Queen Mary 2, she is not an ocean liner, lacking the reinforced hull and greater speed of the Mary and her predecessors. For this reason, Cunard have been criticised for designating the Victoria and the Elizabeth as "Queen" ships. But the fine lines of the ship contrast sharply with the motorised barge looks of many cruise ships.

The great ship sets sail.

A day after the Victoria's departure, her place on the quay was taken by the even larger but rather more mundane-looking MSC Magnifica.

© Christopher Seddon 2010

Feral cats of Istanbul

It is impossible to go anywhere in Istanbul without seeing cats, often congregrating in large groups.

A short distance from the Hagia Sophia, an orange tabby sits on the bonnet of a Mercedes.

Another orange tabby, sitting on the door of a large, derelict wooden house on the Asian side of the city.

© Christopher Seddon 2010

Sunday, 3 October 2010

The enigmatic "Venus" figurines of Upper Palaeolithic Europe

Female carvings are known throughout the European Upper Palaeolithic and are collectively known as Venus figurines, though they predate the Roman goddess by tens of millennia. They are chiefly associated with the Gravettian period, though they are also known from the preceding Aurignacian. The earliest currently known is the 35,000 year old Hohle Fels Venus, a mammoth-ivory figurine recovered in 2008 at Fohle Fels Cave in the Swabian Jura of south-western Germany (Conard, 2009).

Typically lozenge-shaped, these figurines are characterised by exaggerated sexual characteristics, with very large breasts, accentuated hips, thighs and buttocks, and large, explicit vulvas. Other anatomical details tend to be neglected; especially arms and feet, and the heads generally lack facial detail. The contrast with the classical portrayal of Venus could not be greater. The figurines are carved from materials including mammoth ivory, serpentine, steatite or limestone and are often coloured with ochre. Others are made from fired clay, making them among the earliest known ceramics (Vandiver, Soffer, Klima, & Svoboda, 1989). Many have engraved or incised patterns, which may represent hair and clothing.

Left. The Willendorf Venus (left) is carved from limestone and tinted with red ochre. It was discovered in 1908 near Willendorf, Austria and now resides in the Museum of Natural History, Vienna.

Centre. The ivory Lespugue Venus (centre) was discovered in 1922 at the Rideaux cave of Lespugue (Haute-Garonne) in the foothills of the Pyrenees, and is now displayed in the Musée de l'Homme in Paris.

Right. The ceramic Dolní Věstonice Venus (right) was discovered in 1925 in Moravia (now part of the Czech Republic). It is not currently on permanent display to the public.

The figurines are between 22,000 to 29,000 years old.

Since the first examples were discovered in the 19th Century, many have attained iconic status. These include the Venus of Willendorf, which is 11.1cm (4 3/8 in) high and carved from oolitic limestone. The statue was discovered in 1908 by archaeologist Josef Szombathy near the village of Willendorf in Austria, which is associated with the Gravettian period and now resides in the Natural History Museum Vienna.

The figurines are often interpreted as fertility figures, mother goddesses etc, but their real function is unknown. One novel suggestion, by anthropologists Leroy McDermott and Catherine Hodge McCoid, is that they may be self-portrayals of pregnant women. They note likenesses between a photograph of a “Venus” figurine viewed from above and one of a pregnant woman standing with her feet together, viewed from her own perspective looking down on her breasts and abdomen The theory has met with a certain amount of scepticism, but McDermott and McCoid argue that it provides a parsimonious explanation for the features found in representations of the female form from the Upper Palaeolithic (McDermott, 1996; McCoid & McDermott, 1996).

Wednesday, 29 September 2010

You couldn't make it up - but rail companies can!

In the last month, there have been two cases where rail passengers have been fined because they got off the train BEFORE the right stop.

Couple fined £114 for getting off train before their final stop - 6 September 2010

Getting off train early costs Durham professor £155 - 27 September 2010

You don't have to be Mr Spock to see that this is a totally illogical state of affairs. In fact it is barking mad and the words "you couldn't make it up" spring to mind. Unfortunately rail companies can and do, being run by people whose brains operate on wavelengths different to those used by the majority of humans since Upper Palaeolithic times.

The arguement employed by the rail companies is that "it is against the terms and conditions" to get off at an earlier stop if buying a discounted-rate ticket, contrary to something known as "common sense" (admittedly in short supply at rail companies). But it is more than contrary to common sense, I would argue that it is also contrary to law.

A train company can force a passenger to leave a train or penalise them for remaing aboard without a valid ticket. What it cannot do is when a train has made a scheduled stop to force or coerce somebody to remain aboard against their will, or penalise them for failing to remain aboard. I would argue that to do so is not only stark staring mad, it is false imprisonment, a serious offence in common law.

If so then the terms and conditions are irrelevant and unenforceble, because common law takes priority. For example, if the terms and conditions said "If you leave the train before your stop, you will be shot", it is extremely unlikely that anybody trying to implement this policy would escape a lengthy jail sentence. I strongly doubt if the argument "I was only enforcing the terms and conditions" would cut much ice in court.

False imprisonment is a less serious offence, but it is still an offence. If somebody did sucessfully argue in a court of law that preventing somebody from leaving a train early did constitute false imprisonment, then railway companies would be in trouble. Which is why I suspect they backed down in the case of Professor Evans, albeit hiding behind the face-saver of "good will". If the London couple had refused to pay, I suspect the outcome would have been the same.

If this argument is ever successfully tested in a court of law, it will hopefully force and end to this ridiculous policy and it will be a massive victory for common sense.

Sunday, 12 September 2010

70th Anniversary of the discovery of the Lascaux Cave paintings

On 12 September 1940, less than three months after the fall of France, four teenage boys and a small dog named Robot made one of the greatest archaeological discoveries of the last century. The group were walking through the sloping woods above Lascaux Manor, near the town of Montignac, which lies on the Vézère River, Dordogne. They were investigating a local legend about an old tunnel, said to connect Lascaux Manor to the ruined Château de Montignac on the other side of the river. Robot was running on ahead of the boys and was attracted to a deep hole in the ground. Covered with overgrowth, it had been exposed by the falling of a tree.

Accounts vary as to what happened next. According to some versions, the little dog fell into the hole and had to be rescued; others claim the boys used their penknives to enlarge the hole, cutting away earth and removing stones; others suggest that the boys first equipped themselves with picks, shovels and lighting before returning to investigate further. Whichever version is correct, they enlarged the hole and at length they were able to slide through feet-first, one by one, along a semi-vertical shaft embedded with stalagmites, finally reaching a dark underground chamber. There, in the flickering glow of their oil-lamp, they saw prehistoric paintings of horses, cattle and herds of deer, brilliantly multicoloured in reds, blacks, browns and ochres, unseen by human eyes for at least 18,000 years.

Despite the unhappy times, news of the discovery spread rapidly. Villagers flocked to the caves and they soon drew visitors from further afield. Among these was the Catholic priest and archaeologist Abbé Henri Breuil, who was able to attest to the great antiquity of the caves and described them as “The Sistine Chapel of Prehistory”. Another early visitor was Pablo Picasso, who on emerging from the cave, is said to have remarked in reference to modern art “We have invented nothing”.

In 1948, the site’s landowners opened the caves as a tourist attraction, and soon they were attracting a quarter of a million visitors annually. Unfortunately, by 1955 it became clear that CO2 exhaled by the large numbers of visitors was promoting the growth of algae, causing significant damage to the paintings. After a number of unsuccessful attempts to ameliorate the problem, the caves were eventually taken over by the French Ministry of Cultural Affairs and closed to the public in 1963. Only five people a day are now admitted and scholars wishing to visit the caves for research purposes face a lengthy wait for a twenty-minute slot. Ordinary visitors have to make do with Lascaux II, a facsimile of the original which opened in 1983.

The paintings are now believed to be between 18,000 to 19,000 years old – four times older than the Pyramids - and are associated with the Solutrean or early Magdalenian period. There are 915 animals depicted, mainly horses, deer, aurochs (wild cattle) and bison - animals which at that time roamed wild on the steppes of Ice Age Europe (Clottes, 2008). Despite their great antiquity, the Lascaux Caves are certainly not the oldest cave paintings known; that title is currently held by the Chauvet Caves near Vallon-Pont-d’Arc, Ardèche, which are almost twice as old. Considered to be of equal artistic merit with Lascaux, the oldest paintings at Chauvet are now thought to be 36,000 years old (Mellars, 2006), associated with the Aurignacian people and dating to a time when two species of human – Neanderthals and Homo sapiens – coexisted in Europe.

Sunday, 5 September 2010

God does not exist (again)

Robin Dunbar’s explanation (Dunbar, 2006) provides what is probably the most convincing explanation of religion. It is based around theory of mind (the ability to anticipate the thoughts of others) and orders of intentionality (what X might be thinking about Y’s thoughts regarding Z).

Story-telling, science and religion all require 5th order intentionality - eg, when writing Othello, Shakespeare required five orders: he intended (1) his audience his audience to understand (2) that Iago wants (3) Othello to believe (4) that Desdemona intends (5) to run away with Cassio. Probably, though, story-telling was a spinoff – from the ability to, as we would now put it, to “do science”. High-order intentionality is crucial to understanding the natural world – science – which would have been crucial to the survival of early modern humans as the left Africa and attempted to colonize novel environments. To understand seasonal migration patterns of herd animals, the correlation between moon phases, tides and fishing, etc and to share this knowledge with others, would have required equally high orders of intentionality.

The ability to tell engaging stories round the campfire would have been a useful spinoff, good for group morale; serving the same purpose as literature – and indeed cinema and theatre today. But there was another spinoff – religion.

Theory of mind is crucial to religion. To engage in religious activities, I must believe in a parallel world inhabited by beings whose intentions can be influenced by my prayers. These beings must be able to understand what I want – requiring third-order intentionality: I believe (1) in gods that can be persuaded to understand (2) what I desire (3) and will act on my behalf. In fact, more than three orders of intentionality are required in any practical religion because religion is a social activity; a shared belief system and people must share their faith with others in a community.

In his book The God Delusion, Richard Dawkins argues that religion is a “misfiring by-product” of something else (Dawkins, 2006), though in early hunter-gatherer societies, religion would have been a powerful group bonding mechanism and not as entirely malign as Dawkins supposes. Only much later, when humans began living in far more complex societies, was religion used as a means of control by the ruling elite.

However, it is possible that it was responsible for social division as far back as the Upper Palaeolithic, manifesting itself in the cave art of that time. David Lewis-Williams has suggested that art and ritual, while contributing to social cohesion, did so by marking off groups from other groups, thus creating the potential for social tensions (Lewis-Williams, 2002); a trend which has unfortunately continued to the present day. It is probably no coincidence that some of the finest art and architecture ever produced has been religious in nature and if Lewis-Williams is right, the origins of this creativity are very ancient indeed.

Saturday, 4 September 2010

Homo helmei revisited

Homo helmei is one of many human species that has failed to gain widespread recognition. Textbooks tend to either mention it only in passing, or not at all. The species was assigned to the single partial skull which was recovered in 1932 by Professor T.F. Dreyer from the depths of the hot spring at Florisbad, some 50km (30miles) from Bloemfontein, South Africa. The skull comprises the right side of the face, most of the forehead and portions of the roof and sidewalls. A single upper right wisdom tooth was also found with the skull and in 1996 two small samples of enamel from this were found to be 259,000 years old using a technique known as electron spin resonance. In 1935, Dreyer described the find as Homo helmei to mark its distinctiveness from other fossil Homo sapiens. Homo helmei is not widely accepted, largely because it is still known only from this one specimen and it is usually “lumped” into Homo heidelbergensis ("archaic Homo sapiens").

The etymology of Homo helmei is something I have yet to find listed in any textbook and it took a good deal of digging around on the internet until I eventually came across the website of the National Museum, Bloemfontein, which provided the following insight:

The town of Florisbad is named for Floris Venter, a local entrepreneur who in 1912 enlarged the pools at the spring for use as a spa. Later that year an earthquake caused a new spring to open up, revealing stone tools and fossils. During the late 1920s, zoologist Professor T.F. Dreyer and his assistant Ms. A. Lyle carried out excavations in the vicinity of the spring. These were funded by Captain R.E. Helme and produced further quantities of animal fossils. The story goes that Venter feared loss of revenue if his baths were temporarily drained and Dreyer and Ms. Lyle had to wade around in the waters and grope for bones. On one such occasion, Dreyer plunged his hand into the spring deposits underwater and – rather in the manner of Little Jack Horner – pulled out part of a human skull, with his fingers stuck between its eyes!

This was the find later described as Homo helmei - it simply means "Helme's Man" and was named for Capt. Helme, whose funding had made the discovery possible.

Did Lucy use tools

A paper published today in Nature (McPherron et al, 2010) reports the discovery of 3.4 million year old bones from Dikika in the Lower Awash Valley, Ethiopia with cut marks claimed to have been made by stone tools - some 800,000 years before the oldest-known stone tools from nearby Gona. The only hominins known from the region during this time period is Australopithecus afarensis ("Lucy").

The evidence is not overwhelming - no actual tools were recovered and the marks could be due to other causes. But if hominins were butchering carcasses 3.4 million years ago and meat was a significant part of their diet a million years before the appearance of Homo habilis, it would be a problem for the "expensive tissue" hypothesis that proposes that a switch to a meat-based diet released the constraint on brain size, allowing larger-brained hominins such as Homo habilis and Homo ergaster to appear. See this entry on Prof. Hawks ever-informative blog:


Humans in the Philippines, 67,000 years ago

Mijares et al report in the Journal of Human Evolution the discovery of a 67,000 year old human 3rd metatarsal at Callao Cave on the island of Luzon in the Philippines. The bone is gracile and could be from a small-bodied modern human, like the indigenous "Negrito" people of Island Southeast Asia; or it could be from an earlier-type human - the report stated that it was within the range of Homo habilis or Homo floresiensis.

Either possibility is intriguing - if it is modern, then it implies the migrants from Africa must have left before the 65kya date widely touted, possibly before the Toba eruption - despite the most recent genetic evidence pointing to later rather than earlier dates for the migration. If on the other hand it is pre-modern, then as with Flores we are left with the question of how did archaic humans reach an island which was never connected to the mainland? I've always felt that Homo floresiensis is a downsized version of Homo erectus, descended from a small group who reached Flores by accident after being swept out to sea by a storm or tsunami - but another possibility is that Homo floresiensis was a sea-faring species that established itself on at least two islands in ISEA.

Best to reserve judgement for now.

The Artificial Ape, by Timothy Taylor

On order from Amazon. Sounds interesting and I need to read it, if only for professional reasons. Taylor apparently cites the reduction of lactose intolerance in humans as an example of technology bringing about evolutionary change. Originally, when weaned, the ability to process milk in humans was “switched off” as it was no longer needed. In other words, nearly all adults were lactose intolerant. But with the “secondary products revolution” that followed the Neolithic adoption of agriculture, milk became a useful food source; lactose intolerance became a disadvantage and was selected against.

However, one ”pet” example of such change (I DON’T know if this is in Taylor’s book) has now been shown to be dubious - the change from large ape-like guts in the australopithecines to the smaller guts of humans came about through tool use, enabling humans to butcher carcasses and switch to a meat-based diet. Smaller, less energy-expensive guts were required for this higher quality diet, opening up the way for our large, gas-guzzling brains.

But: australopithecines (not just late ones like A. garhi) may have used tools (McPherron et al, 2010), and probably didn’t have large guts (Haile Selassi, 2010). Both discoveries are very recent, but the inclusion of meat in the australopithecine diet and implied tool use has been suspected for over a decade (Sponheimer & Lee-Thorp, 1999; Teaford & Ungar, 2000).

The trouble with writing in this field is that it is VERY easy to be out of date!

A book about human prehistory

I have abandoned this blog for over six months, my efforts having been diverted to writing a book about human prehistory. This project now nearing the three-quarters stage.

The as yet untitled work describes how early ape-like hominins such as Australopithecus evolved into more human species such as Homo habilis and Homo erectus and how from these ancestors, modern humans arose and eventually left Africa and populated the rest of the world. The last, still to be written quarter of the book covers what happened when modern humans encountered their close cousins, the Neanderthals and how, at the end of the last ice age, humans adopted agriculture, began living in more complex societies - leading to state-level civilizations and ultimately the world as we now know it.

The project has been in the making for many years, but after my redundancy last year I decided that over 30 years in the IT industry was enough for one lifetime and I took early retirement in order to work on my book full time.

Friday, 5 February 2010

Chimpanzee and human Y chromosomes

There was an interesting letter in Nature last week about a comparative study carried out between the Y chromosomes of humans and chimpanzees. The Y chromosome is one of the two sex-determining chromosomes in most mammals, containing the SRY (sex determining Y) gene, which triggers the development of male gonads. The primate Y chromosome is hundreds of millions of years old and given that chimps are so closely related to humans, one would expect to see little difference between the Y chromosomes of the two species. In fact the male specific regions (MSY) of the two show considerable differences, more consistent with a divergance time of over 300 million years rather than just 6 million years. The authors of the paper attribute the differences to the prominent role in sperm production of the MSY and to differences in mating behaviour between the two species. The heightened sperm competition in the chimpanzee lineage may account account for the changes; the paper suggests that by comparison the human MSY is little changed.

The implication is that the chimpanzee promiscuous mating strategy is the derived behaviour and the mating strategy of the human/chimp last common ancestor was more human-like than chimp-like. This in turn would support Owen Lovejoy’s controversal conclusions that Ardipithecus was monogamous in its mating habits, though this point is not made by the author of the Nature letter.


Hughes, F.; Skaletsky, H.; Pyntikova, T. et al (2010): Chimpanzee and human Y chromosomes are remarkably divergent in structure and gene content, Nature 28 January 2010 Vol. 663 pp 536-539

Lovejoy, O. (2009): Reexamining Human Origins in Light of Ardipithecus ramidus, Science 2 October 2009 Vol. 326 p 74

Sunday, 10 January 2010

Big Freeze - January 2009

The worst cold weather since the 1980s brings the usual chaos and total inability of the authorities to cope, but does at least make for a photo opportunity without having to brave the cold!

© Christopher Seddon 2009

Monday, 4 January 2010

Pulteney Bridge, Bath

Completed in 1773 and designed by Robert Adam, Pulteney Bridge crosses the River Avon at Bath, England. One of only four bridges in the world with shops across its full span it is now a Grade I listed building.

© Christopher Seddon 2009

Avon Valley Railway

The Avon Valley Railway offers a six mile return train ride along the former Mangotsfield to Bath Green Park branch of the old Midland Railway. It is based at Bitton Station, midway between Bristol and Bath. The former Midland Railway station has been restored from a derelict state to provide excellent visitor facilities. Trains are hauled by either a tank engine or a diesel yard shunter.

© Christopher Seddon 2010