Saturday, 25 May 2013

Rural Relaxation - Getting one's feet wet

In March last year I posted this picture (A Rainfall Crisis looming in Eastern England) which was actually chosen to show how low the water had got in the College Lake Nature Reserve near Tring! College Lake is actually a disused chalk pit and when quarrying was abandoned it was estimated that that water entering the lake would seep away through the chalk. The calculations as to the equilibrium level were badly wrong and the water rose to flood the track through this gateway some years ago. However they had seem to stabilize and during the drought of 2011 and early 2012 the water actually dropped to revel about an extra foot of this gate.

Thursday, 23 May 2013

Did the Neanderthals die out because humans had a better culture?

Two recent news items, coupled with earlier reports that Neanderthal children matured faster than human children, could be relevant to Neanderthal intelligence and perhaps to the species becoming extinct.

The paper New insights into differences in brain organization between Neanderthals and anatomically modern humans by Eiluned Pearce, Chris Stringer and R. I. M. Dunbar notes that while the Neanderthal brain size was similar to Homo sapiens, more of the brain was devoted to sight and controlling a larger body.

The paper Barium distributions in teeth reveal early-life dietary transitions in primates by Christine Austin et al examined a Neanderthal tooth as estimated that breast feeding in Neanderthals may have only continued for about 14 months compared with 30 months in human non-industrial societies.

Friday, 17 May 2013

More about the Denisovans DNA - and interbreeding

Following my previous post I am most interested to see the post Denisova and aDNA: an embarrassment of riches on The Rocks Remain and New Denisova and Neanderthal DNA results reported on John Hawkes Weblog. There is clear evidence that there was interbreeding between Denisovans and Neanderthals - but there is also evidence of yet another human subspecies.

Sunday, 12 May 2013

Human Evolution - Asian or African Origins and Family Trees

The current New Scientist contains an article Our Asian Origins by Colin Barras which suggests that our ancestors might have moved from Africa to Asian and then moved back again and illustrates it with a modified classic human family tree – when evidence is rapidly accumulating that such a view is over-simplistic.

A typical classic human family tree
with no cousin links.

From The Quest for Human Origins
In order to understand human evolution we need to get a grip on the mechanisms – and to realise that we will never have more that a fraction of a millionth of the information we would need to get a complete picture, and the fragments of bones we find represent only some of the environments our early ancestors lived, with some environments being totally unrepresentative. Remains from different places with different features and from different dates are given different species names – but this does not automatically mean that the living creatures could not have interbred, had it been possible for them to meet.