Wednesday, June 26, 2013

The last days at Vanguard

The pace gathers as we reach the last days of the season at Vanguard Cave. We've found the biggest of the ponds inside the cave so far, this one covering the entire floor space (below):

Geomorphologist, Professor Rodriguez-Vidal keenly inspects the remarkably well-preserved pond, with the complete stratigraphy behind and below him.

Specialists from different laboratories are now here sampling the excavated sequences, here for example to date it with OSL (above and below):

While others sample for geochemical analyses (below):

Below is the complete stratigraphy as excavated so far in 2012 and 2013. Under 4 metres of the 17-metre sequence so far!

Vanguard may be coming to an end for now but we have another month ahead of us, in Gorham's Cave!

Monday, June 24, 2013

An earthquake that lifted the Rock!

Our team's geomorphologist Professor Joaquin Rodriguez Vidal came up with an amazing discovery the other day. Examining the excavation at Vanguard he saw this broken stalactite which had been embedded within the sediment until it was excavated by our team. With other evidence of significant deformation of cave materials elsewhere in the site, he concluded that this represented a large earthquake that shook the Rock some 40 kyr. The stal broke but the sediment it was in held it in position. Joaquin reckons the quake was local, with its epicentre on the Rock itself. The result was the sudden elevation of the Rock by 2 cm!

Friday, June 21, 2013

Further update from Vanguard Cave

Work continues at the back of Vanguard Cave and more material is now appearing as we descend the levels and begin to reach areas that are less confined and would have allowed the Neanderthals to move about with some freedom.

Evidence of their presence is revealed by flint flakes like the one above. These levels are revealing important use of limpets, notches on their shells (N in picture below) revealing where the Neanderthals inserted their knives to prise the limpets from the rocks.

Below the dried pond that we discovered last week, we found an even larger one, indicating that this part of the cave received intermittent supplies of water (2 photos below).

This week we've also been hosting visits of members of the Gibraltar Heritage Trust, who have had an opportunity to see our work close hand, and even help out on sieving duties!

The work doesn't end when we return from the cave. Each evening several hours in our field station are spent going through the day's finds before sending them to the main lab in the museum.

Monday, June 17, 2013

Visit Natur-al-Andalus

Visit our sister blog at http// to see images like this one as we reconstruct the landscape outside Gorham's and Vanguard Caves at the time of the Neanderthals

Sir, would you like yours medium or well-done?

The third recent paper [1] that returns us to the superior modern humans takes the biscuit. This is a very simple idea – Modern Humans ate the Neanderthals to extinction! Can you believe this? After a convoluted argument the authors concede that:

“Therefore, although at this time there is no clear evidence of widespread slaughter of Neanderthals by AMHs, this could simply be due to the taphonomical difficulty of preserving human remains.”

In other words, we have no evidence but we like the idea so why not? Let’s blame lack of evidence on poor preservation. Well, I would suggest that we adopt the alternative view: let’s find the evidence and then we can talk.

With this I rest my case: three recent papers, coming from different angles but all trying to cling on to the modern human superiority faith. I repeat a challenge that I have often made to the replacement gurus: show me one, just one, piece of conclusive evidence that modern humans out-competed, indirectly or more directly as this last paper claims, the Neanderthals. It’s simple really, get the data and the discussion will be over; in the process we will all be spared from this seemingly endless flow of speculation.

[1] P. Hortola, B. Martínez-Navarro (2013) The Quaternary megafaunal extinction and the fate of Neanderthals: An integrative working hypothesis.  Quaternary International 295: 69-72

Sunday, June 16, 2013

When time froze

One thing that has always amazed me about Vanguard Cave is how short-lived events have been trapped, frozen if you like, as easterly winds rapidly brought sand in from outside the cave and covered these moments. I can give you a beautiful example, from yesterday.

Water formed a pool inside the cave, below the hearth that we have been excavating, some time over 40 thousand years ago. It then dried up and was covered by the dune. The imprint of the caked mud was preserved as you can see in these images. Isn't it amazing?

Work on the hearth continued. Above and below are sections through the hearth, showing the fragments of charcoal and burnt areas nicely.

All this is happening at the back of Vanguard Cave where space is at a premium. At least you are in the shade which is great in the hot conditions. The guys sieving outside try to generate their own shade!

Meanwhile, Gerry continues with the cave topography...

Lunchtime in Vanguard Cave

Friday, June 14, 2013

Bright Eyes

The second of the three studies that I referred to in my post of 11th June talks about the apparently larger eyes that Neanderthals had when compared to contemporary modern humans [1]. The sample sizes are miniscule, especially when considering the large geographical regions and time periods covered by the study. Although the authors claim to have studied a sample of 28 Neanderthals and 38 modern humans from the period 27-200 kyr (yes that’s a pooled sample covering 173 thousand years!) some of the comparisons involve much smaller samples. Thus in Table 1 of the paper the comparison of orbital area has sample sizes of 6 for Neanderthals and 10 for modern humans! Anyway, let’s not split hairs and grant the authors the bold claim that Neanderthals had bigger eyes than modern humans. What does this mean?

The first assumption, which may be logical but is an assumption, is the following:

“We have demonstrated that Neanderthals had significantly larger orbits than contemporary AMHs, which, owing to scaling between the components of the visual system, suggests that Neanderthal brains contained significantly larger visual cortices.”

Remember, they don’t know that they had larger visual cortices, they assume it. Fair enough, maybe, but what next? Of course, they start to attack the poor Neanderthals for their inferior cognition:

“In addition, previous suggestions that large Neanderthal brains were associated with their high lean body mass imply that Neanderthal also invested more neural tissue in somatic areas involved in body maintenance and control compared with those of contemporary AMHs.”

Now they’re citing previous suggestions to back up their assumption which is drawn from the conclusion that Neanderthals had bigger eyes than modern humans. The castle is taking shape in the skies above our heads. The story goes on:

“While we cannot partition fossil brains down to the refinement of specific frontal regions, there is at least sufficient evidence from comparative studies of primates to justify using whole brain volumes to estimate cognitive capacities as a first step.”

From this they go to conclude that Neanderthals had reduced cognitive capacities relative to modern humans. To complete the castle that is now flying light years above our heads, they move to the archaeological evidence:

“What little archaeological evidence there is offers support for this: compared with Neanderthals, contemporary Eurasian AMHs had larger [2], more geographically extensive social networks [3,4]. Group size is a convenient index of the cognitive ability to deal with increasing social complexity and may thus evidence more general differences in sociocognitive abilities between these taxa.”

The references cited (my numbers) are worth checking out. Do read them and see what you can find that really supports these claims conclusively. They seem to forget that Neanderthals also show evidence of increased geographical networking in parts of western Europe when climate change opened up their favoured landscapes [5]. So were these extended networks a reflection of modern human improved cognition over Neanderthals or were they simply a reflection of the nature of the landscape they were living in? Pretty important you would agree, as a lot hinges on this for the authors. By the way, don’t lose sight of the papers results which were about eye sizes.

They continue with the presumed differences in geographical networking:

“Such differences may have had profound implications for Neanderthals. First, assuming similar densities, the area group size estimated from standardized endocranial volume covered by the Neanderthals’ extended communities would have been smaller than those of AMHs. Consequently, the Neanderthals’ ability to trade for exotic resources and artefacts would have been reduced, as would their capacity to gain access to foraging areas sufficiently distant to be unaffected by local scarcity. Furthermore, their ability to acquire and conserve innovations may have been limited as a result, and they may have been more vulnerable to demographic fluctuations, causing local population extinctions.”

What??? Are we reading the same paper? Where did all this come from and what does it have to do with larger eyes?

“Whereas AMHs appear to have concentrated neural investment in social adaptations to solve ecological problems, Neanderthals seem to have adopted an alternative strategy that involved enhanced vision coupled with retention of the physical robusticity of H. heidelbergensis, but not superior social cognition.”

Aah, here we go - superior social cognition. They even bring in poor old heidelbergensis, into it now. We have to accept religiously that heidelbergensis existed as a single species and that it was the ancestor of the Neanderthals and not of the modern humans. So the Neanderthals remained physical brutes with good eyes and this prevented them from being as intelligent as modern humans. Now for the piece de resistance

“While the physical response to high latitude conditions adopted by Neanderthals may have been very effective at first, the social response developed by AMHs seems to have eventually won out in the face of the climatic instability that characterized high-latitude Eurasia at this time.”

Back to the high latitude occupation by Neanderthals. Haven’t the authors realised yet that Neanderthals were a mid-latitude taxon that rarely ventured into higher latitudes? I would have thought that they would have been aware of how marginal high latitudes, for example the United Kingdom (see [6]), were for these people. So how can we model the scenario that they had large eyes to deal with poor light and darkness in the latitudes that they hardly ever lived in? I suppose that so long as it serves to put the Neanderthals down and bring our ancestors to the cognitive pinnacle, it is all right. Faith prevails once again.

[1] E. Pearce, C. Stringer, R.I.M. Dunbar (2013). New insights into differences in brain
organization between Neanderthals and anatomically modern humans. Proc. Roy. Soc. B. 280: 20130168

[2] P. Mellars, J.C. French (2011) Tenfold population increase in western Europe at the Neandertal to
modern human transition. Science 333, 623–627.

[3] C. Gamble (1999) The palaeolithic societies of Europe. Cambridge, Cambridge University Press.

[4] P. Mellars (1996) Symbolism, language and the Neanderthal mind. In Modelling the early human
mind (eds P Mellars, KR Gibson). Cambridge, Cambridge University Press.

[5] C. Finlayson (2004). Neanderthals and Modern Humans. An Ecological and Evolutionary Perspective. Cambridge, Cambridge University Press.

[6] C. Stringer (2006). Homo britannicus. London, Allen Lane

Wednesday, June 12, 2013

Update from Vanguard Cave

The sieving station is now up-and-running (above) and we've started picking up some good climatic indicators, especially small reptiles and amphibians (below)

The area that we have been cleaning was ready for excavation this morning, showing a nice range of levels (below). The top level (9) was showing charcoals in section which was promising.

Our expectations were more than met as excavation started to reveal a hearth (below). It will become clearer as we excavate but we already picked up two flakes and a few herbivore bones, including some burnt ones. The hearth would have been made by Neanderthals maybe some 45-50 kyr. The date is no more than a rough guess at this stage, based on 40 kyr levels above this part. The next few days will reveal more but it's exciting to find Neanderthal activity high up in the sequence.

I leave you with some images of today's sieving activity...and they're not hanging out their washing but the sieved material out to dry!

Close of play today

Tuesday, June 11, 2013

Those superior modern humans...

The spectre of cognition looms once again on the Neanderthal agenda. For years many authors have sought to maintain the position that our ancestors – the “modern” humans – were cognitively superior to their contemporaries, the “archaic” humans, including the Neanderthals. It was this superior intellect that was the cause of the rise of our species and the demise of all others. This has always been a difficult position to justify as there is no real evidence that this was the way in which the Neanderthals disappeared from our planet or indeed of how we colonised it. In the absence of evidence, hypothetical mutations that suddenly made us modern around 50 thousand years ago (kyr) have been postulated and the expansion of these modern humans into Europe has been inferred on the basis of stone tools that have been assumed, with little supporting evidence, to have been made by the new arrivals.
I have taken these arguments apart over the last few years, showing that the cognitive superiority and replacement argument is no more than a statement of faith which is unsupported by evidence. It is a kind of belief system that just does not go away. Even when we now know that our ancestors interchanged genes with the Neanderthals, to the degree that their genetic signal persists in us today, we insist in drawing distinctions. We seem obsessed in perpetuating the myth that we are the pinnacle of evolution; to maintain this position we must relegate all other humans, Neanderthals included, to a second plane.
In today’s blog I want to highlight the first of three recent papers that continue with the insistence that modern humans were cognitively superior to Neanderthals and that it was this that caused their extinction. I will deal with the other papers in subsequent posts. The three papers have one thing in common: they provide no direct evidence in favour of what they claim. Let’s start with the first one, a paper published last year in the Proceedings of the National Academy of Sciences USA (PNAS) [1]. The paper examined evidence of a volcanic eruption that occurred in southern Italy some 40 kyr. Evidence of the ash from the eruption in caves occupied by Neanderthals and modern humans was used to mark events before and after. The authors concluded that

“the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on Neanderthals or early modern humans in Europe.”

That may be so in so far as the limited geographical area that suffered the impact of the volcano goes; but absence of evidence is not proof of the alternative hypothesis. Despite this, the authors went on to say that

“We infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters.”

In other words, they could not find evidence of the impact of the volcano on Neanderthals or modern humans and concluded that modern humans therefore had a greater impact on the Neanderthals; but no evidence of this modern human impact was provided. A case of “it must have been so”.

My take: the Neanderthals had gone extinct in the region by the time the volcano erupted, as shown by the authors. This means that the volcano could clearly not have had an impact on the Neanderthals as they were by then extinct! So we cannot test the impact of the volcanic eruption and subsequent climate on the Neanderthals. The modern humans, if that is what they were as we are relying largely on stone tools to identify them, may well have come into the region in large numbers to occupy the empty ecological space left by the volcanic eruption. There are just too many unknowns for us to tell what was going on...

[1] J. Lowe, et al. (2012). Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards. PNAS 109: 13532-13537

Monday, June 10, 2013

Getting the job done

I have decided to start this blog so as to open up discussion on the many topics that are constantly being published about our evolution. I'm hoping that we can discuss these and our own fieldwork and the results of that work. There is a lot to cover so please keep visiting! I also want to give a flavour of the day-to-day work that is involved behind all this work that ends up in a few thousand words of a paper - the stuff that doesn't get into the "Methods" section. I thought I'd start with this and tell you what we've been up to today.

We've just started our summer excavation season here in Gibraltar. In June we will be excavating Vanguard Cave. This cave was occupied by the Neanderthals. We're not sure for how long just yet - that's part of the reason why we're excavating here. Vanguard Cave lies just at the entrance to the Mediterranean Sea, at the base of a 426-metre (1492 ft) cliff. Logistics are a problem and sometimes it is easier to transport heavy kit by boat than bringing it down the cliffs. Today we had to set up a sieving station and we had to get two 100-kg containers onto the site. These were brought by boat but the rocky shore prevented the boat from getting in too close.

So what we did was to get Gerry and Darren from our underwater archaeology team to get into the water and safely guide the tied containers ashore where others from the team were waiting to haul them ashore and onto the chosen location where they will live for the next two months. The following pictures speak for themselves.

Above: both in place and ready for action...but the pumps and hoses needed to be brought down the cliff...

So that's all in a day's work! The pic above gives an impression of the scale of the cave. Keep visiting and I'll mix living experiences such as this one with more general topics. And who knows what we'll be finding in the caves during this summer season!