Abberton and more human history.

The car is finally fixed, so a quick drive to Abberton to make sure all is well.

The Canvasback was being seen from Billet's, and was whilst I was there, but heat haze etc meant I couldn't claim it. I headed off to Abberton Church for the Lesser Scaups that had been seen from there, and found nothing of interest, although as I was leaving here was a familiar call and two adult Mediterranean Gulls flew over. 

Back to Billets and this time it was playing ball. Decent views, that almost linear sloping facial profile and the long black bill meant it could be repeatedly be picked out.

Finally Layer Breton Causeway and two Spoonbills high up in the heronry, and another one asleep in the corner.

So, human evolution ... I bought 'A very short introduction to Human Evolution.' A decent read, but my takeaway view was that whilst people were doing great detective work in finding and then analysing remains, we don't have enough anywhere close to enough evidence to form a definitive picture of humanoid evolution prior to Homo Sapiens arriving on the scene. Humanoids seem to have been in existence for at least 6 million years when we split from Chimpanzees. Given homo sapiens have been here much less than a million years that's a lot of evolution before we get to us.

For people of my/our vintage who can remember the dawn of DNA profiling, the speed with which DNA sequencing and associated understanding has developed has been amazing. For me and probably all of you birding being mainly a male pastime, we have 46 chromosomes of which 44 are in pairs through the process of myosis, and then there is an X and a Y. The Y comes from our father, which comes from his father etc. Except each time it is replicated there is a small error (known as 'replication error'), so it is nearly but not quite identical. 

Now because, as you are reading this blog, hence you are a smart person, you will be saying 'hang on, that means we can compare any two male Y chromosomes and have a reasonable idea how many generations back they had a common male ancestor. And we should be able to work out whether there was just one common male ancestor.' And the answer to both those questions is, amazingly, yes we can. with assumptions on time between generations and rate of replication error, we get back to a single man about 250,000 years ago, probably in West Africa. We can do similar with women who inherit mitochondrial DNA, and that ends up being 100,000 to 200,000 years ago.

The logical process is a bit tricky here. What if men had evolved 500,000 years ago, but due to disease/war/starvation the population went up and down and most died out with just one man and his offspring surviving into the current time? So we can have a first time for a common ancestor, and that may not be the same for men and women, but it may be that homo sapiens evolved before then.

Anyway, this is all very interesting but the British Isles don't enter the picture until much later. We currently believe all humans outside Africa are descended from people who left 60,000 years ago. At that time the British Isles were covered in ice. The last ice age, or Last Glacial Period—occurred between approximately 115,000 and 11,700 years ago. At its peak, the ice was several kilometres thick. There were refuges in southern Europe where Homo Sapeins survived but not the British Isles. So the history of people in the British Isles starts about 12,000 years ago, or 10,000 BC.