The BBC have run a story outlining how if the present trend continues, the human race will split in two: http://news.bbc.co.uk/1/hi/uk/6057734.stm

"Evolutionary theorist Oliver Curry of the London School of Economics expects a genetic upper class and a dim-witted underclass to emerge.

The human race would peak in the year 3000, he said - before a decline due to dependence on technology.

People would become choosier about their sexual partners, causing humanity to divide into sub-species, he added.

The descendants of the genetic upper class would be tall, slim, healthy, attractive, intelligent, and creative and a far cry from the "underclass" humans who would have evolved into dim-witted, ugly, squat goblin-like creatures. "

Oliver Curry, while working in London, has apparently been walking around his city with his eyes shut.
If he took a stroll around the crack-ridden streets of London, chanced a walk on the grim and violent streets of Nottingham, or surveyed the squalor, filth and incest of the Isle of Wight, he would see that half a century of socialist intervention in the UK has bred a frightful underclass, which is a significant minority within that country.

The people's paradise that was supposed to be the result of post WW2 social programmes instead spawned a sub-species of monsters.  They have a homogeneity across the entire country which hints at some kind of reverse trend in evolution.

The first symptom is an aversion to work:  there are children leaving school who will never have a job.  Their parents have never had a job and their grandparents have never had a job.  Welfare has made work an unecessary burden on their lives for 50 years.

The second striking feature about this underclass is their shortness of stature.  This is the result of two factors: smoking from and early age, and a diet which contains virtually no fruit or vegetables. 

Thirdly and most frighteningly, they have a grey, jaundiced look to the skin, and even the children have creased, venal faces.

This repulsive sub species conduct lives of Hogarthian squalor, they are mostly functionally illiterate, they aimlessly wander the streets looking for something to steal to buy drink or drugs - and a fact which has been consistently hushed up by the UK Government - the squalor and intimacy of the housing projects they live in have made them hotbeds of incest.  The kinds of birth defects which once were the preserve of unfortunate rural districts, are now occuring regularly in the heart of the UK's major cities.

Stratification is here, but it is not the kind we would wish.  It is worth remembering that in HG Well's classic, it was the Morlocks that fed on the Eloi.