Probe

Just had another visit from a born-again Christian who has been coming in for early morning discussions of late. He was, at first, a little cagey about revealing his motivation. His opening questions were about the ages shown on the labels in front of the fossils. To begin with, he just said he doubted that the earth was millions of years old but give his reason as being that it felt wrong.

Over subsequent visits, he has talked more about his religion, though, and shown that his scepticism of science is really based on countering anything that may undermine his interpretation of the bible. This involves, it transpires, an estimation of the age of the earth at somewhere between 6-10 thousand years. Back to that again. I know - it's just something of a sticking point with me. It seems to me, admittedly a firm atheist, there can be ways of incorporating new information into a faith and that people should not shoot themselves in the foot by flatly denying the obvious. By 'obvious' I'm not saying the earth is definitely 4.55-4.6 billion years old - science works by constantly revising current thinking - but that an age measured in only thousands of years is easily dismissed as nonsense. There are living trees almost 10,000 years old, and so far at least one example much older.

Anyway - he is a very nice guy and clearly very driven. He is, to his great credit, able to at least listen to my responses to his questions and give them some thought. I suspect I will be seeing more of him.

Treasure

Some guy found a huge pile of gold stuff while metal detecting in Staffordshire. I would like to find something like that.

Quite often customers confuse archaeology with palaeontology and make Indiana Jones jokes. I'm not like Indiana Jones, really. I realise that's hard to believe. Archaeology is concerned with the study of past human activity, culture and society through found artifacts and buildings etc. There is an element of overlap when it comes to the fossil record of human ancestry, but not much. Given humans have only been around for the blink of an eye in geological timescales, it's a small (but very interesting) area of the subject. A good example of palaeontology and archaelogy working together is studying the spread of tools across the continents. It's a useful addition to the hominid fossil record, and within more restricted ranges even the use of specific materials and designs can be tracked. Shows how people were moving from place to place, and perhaps early signs of trading and so on.

Denver

There's a big fossil and mineral show on in Denver at the moment. It's one I've never been to, though is a good size and is a regular for many of my friends. It's tough seeing all the pictures - feel like I'm missing out.

It would be difficult to justify going. I see most, if not all, of the dealers I'd want to at the Tucson show, and I'd have to buy a considerable amount to off-set the travel costs and so on. Same 'problem' with the Munich show and St Marie... One day I'll probably go, just to experience the show.

Mini rex

Quite a few articles around today about a description of a very small tyrannosaurid from around 35 million years before the larger-sized tyrannosaurid body shape started to appear.

Raptorex kriegsteini has lots of the characteristics of its famous relative, T. rex, and importantly shows that the distinctive features such as the skull shape and small forelimbs were in place well before they got all super-sized. These dinos were only 8 feet long, and weighed about the same as my friend Keith. Less than me.

The surprising thing about the discovery is just how little the body plan changed as it was scaled up. There were a few tyrannosaurs around North America and Asia throughout the later Cretaceous, and they weren't all as enormous as T.rex - a good example being Nanotyrannus lancensis, which deserves a post of its own - but the typical features are present in all.

Collecting glasses

Tektites are lumps of natural glass formed from terrestrial rock on the impact of a meteorite. The instantly molten rock is thrown high into the air, cooling and solidifying on the way down, so is often distributed some distance away from the impact crater. Not all meteorites have created tektites -in fact so far there are only a handful of tektite sources.

The first tektites were found in 1787 in the Vltava or Moldau River, in what's now the Czech Republic. These are now called Moldavite, and are perhaps most appealing example. They vary slightly in colour, but are generally a deep bottle green. They're prized for jewellery now and are often cut and faceted for setting. Moldavite is linked to a huge meteorite impact in Germany, the Nordlinger Ries crater, which occurred around 14 million years ago.

Elsewhere, the Chesapeake Bay impact in the US has produced tektites found in some Southern states, a grouping of sites around Western Africa are thought to link to an impact in Ghana and tektites found in Australia, China and South East Asia may come from one huge impact. In this case, though, the crater has yet to be identified and there is a good chance they may be from more than one event.

While the impact theory is almost universally accepted, there are a few other suggestions for tektite formation. The most interesting is that they are little lumps of lava from volcanoes on the moon. As wild as this sounds, there is at least some evidence to lend it some weight. Tektites are very dry. Drier than bone. Drier than a towel in a tumble drier in the desert. Moon lava is also very dry. And so... Well - there's more to it than that. I'm being glib.

Another stone I should bring up here is the controversial Libyan desert glass. Although it was first found a long time ago - tools were made with it in the Pleistocene - it still isn't entirely clear exactly what it is. Prevailing opinion now puts it as a tektite, though the shapes it takes are not the usual tektite forms, it is far lighter in colour and it has a far higher silica content than normal. I can't see how this cannot at least be partly attributed to the terrestrial rock in the area of impact, though. If the meteorite hit a sandstone, might the resulting tektites not be silica-rich? Still lots of research being done on this interesting rock, though.

Out of Georgia

There was an interesting talk at the British Science Festival in Guildford yesterday about hominid finds in Dmanisi, Georgia. The story itself is not new, with the first discoveries being made back in early 1990s, but the talk discussed the current thinking on the finds. You can read a little about it here, but the article is more than a little hyperbolic in its claims that the finds demolish the Out of Africa theory.

The skeletons and skulls date to around 1.8 million years old and are a more primitive species than Homo erectus, the folks responsible for what had previously been considered the first road trip out of Africa, around 1 million years ago. H. sapiens, us lot, didn't get round to heading North until relatively recently, maybe 100,000 years ago. Imagine the packing that went on. 'Look, I'm sure you're not going to need all those loin cloths. Just bring the extra hairy ones; it's probably going to be freezing.'

While still not certain, the Dmanisi finds resemble a more developed H. habilis or possibly closer to H. ergaster. It had been thought that erectus had been the most primitive hominid to make the trip into Eurasia. While the Out of Africa theory had regarded two major excursions from the continent as being the most significant, it had never ruled out any number of others at different times. It seems that these early Georgians had made the journey some considerable time before the more evolved erectus left for pastures new, but that does nothing to undermine the theory's main points, as the species was clearly a bit of an evolutionary dead end.

The article linked to above suggests that at some point the Georgian hominids may have made the return journey to Africa and continued to feed into the evolutionary melting pot. I see no need for this to have happened at all. Seems much more likely that not everyone went North in the first place and that probably the majority of the species stayed at home, where it was warm and they knew they could get tasty antelope.

Anyway - it's a topic I find fascinating. One thing is certain - as more finds are made, more evidence is revealed and we will be able to add to the story of human evolution and expansion from Africa.