In Our Own Image - Evolving Humanity

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01Human Cultural Evolution Versus Genetic Evolution2011081620110818 (R4)Human uniqueness takes many forms: we can communicate complex ideas; we have developed technologies, such as medicine and transport; and we change our environment to suit our biology. But how does human culture affect our biology - our genes?

Geneticist and broadcaster Adam Rutherford explores the complex and sometimes controversial world of human evolution. He talks to geneticists, evolutionary psychologists and anthropologists to try and understand and untangle the relationship between our biology - our genes and our cultural and social behaviour.

Have we, as Professor Steve Jones thinks, evolved beyond evolution by natural selection? He thinks that in the western, developed world, the normal driving force for evolution by natural selection is tailing off. We are all having a similar number of babies and those children are surviving and having children of their own. The impact of this is that there's no longer an opportunity for genes which may be beneficial to be selectively passed on. As these trends increase, he says that 'if we haven't already stopped evolving, we soon will.

Seeing evolution in action isn't easy, by its very nature, it only occurs on a generational time-scale. But there is evidence of very recent human evolution, some of which may still be occurring now. Since the Human Genome was decoded, geneticists are finding regions of genetic code which are relatively stable amongst populations - the so called 'Darwin's Fingerprint' - evidence that these genes have been selected for and passed on, in the past. Examples of these include genes for lactose tolerance, which evolved in dairy herders, as recently as 3000 years ago, and is thought to still be spreading as the world switches to a dairy-rich diet. Disease-resistance is also seen in our genomes, as is apparent increases in the length of time women are able to have babies.

Probably the most important area of human evolution since we split from our last common ancestor with chimpanzees, is in the development of our brains. But there is very little evidence that our brains are still evolving - biologically. Being more intelligent does not mean that you will have more babies and pass your 'brainy' genes to more children.

Cognitive psychologist, Steven Pinker thinks that 'just because our society is changing and our way of life is changing beyond recognition doesn't mean that our genes are changing as well.

But, Kevin Laland, at St Andrews University says we're not just passive actors in our genetic destiny. In fact it's our ability to change our environment which not only drives out cultural evolution, but has a direct effect on our genes as well.

Many recent examples of human evolution have happened in closed societies and are a result of pairing up within a limited gene pool. One example is the Ashkenazi Jews, who may have evolved increased intelligence, as well as a number of heritable diseases. With societies now starting to open up, and the increasing acceptance of interracial and cultural marriages; ease of travel; and increased connectivity through the internet etc. Adam Rutherford asks if we're heading for a much more homogenous society? And what will this mean for our genetic diversity and possible future evolution?

Producer: Fiona Roberts.

Is human culture stopping us from genetically evolving?

Adam Rutherford asks how talking, travelling and technology affect human genetic evolution

02Human Cultural Evolution Versus Genetic Evolution2011082320110825 (R4)Human uniqueness takes many forms: we can communicate complex ideas; we have developed technologies, such as medicine and transport; and we change our environment to suit our biology. But how does human culture affect our biology - our genes?

Geneticist and broadcaster Adam Rutherford continues to explore the evolutionary fate of the human race...

Following on from Programme 1 where, Adam discovered that humans are still evolving, but perhaps not as much as we have done in the past. And he learnt that our culture (medicine, technology etc.) certainly does interact with our biology. This week, he explores more how genes and culture interact and asks whether the choice of who we have children with is changing and whether this has an effect? He finds out if the increase in global travel is opening up more options for us to find partners and tries to pin down an answer to the often asked question - are we getting brainier?

Many people think that evolution is always progressive and always for the best. But Steve Jones says that this is a common misconception, where Darwinian evolution gets muddled up with Lamarckism. French biologist, Jean Baptiste de Lamarck saw a pattern in evolution - which he called, 'the Law of Necessary Progress' - that it was built in that things were bound to get better. But evolution by natural selection is not like this - it's just a mechanism that just cranks around... So a future, where we evolve large thumbs for better texting and playing video games and even become more intelligent, isn't all that likely.

A major reason why humans are changing genetically nowadays, is due to the impact of travel and globalisation. Professor Steve Stearns is excited by the prospect of grandchildren from his youngest son who has married a Tanzanian lady - if they have children, 'there will be genes meeting, that haven't seen each other for more than a hundred thousand years.' This genetic refreshment caused by out-breeding could spell a genetically healthy human future.

Professor Spencer Wells, National Geographic Explorer-in-Residence and Director of The Genographic Project, is attempting to trace human migrations throughout history - tracking down where individuals have come from - and he is already seeing massive genetic diversity in cities all over the world.

Professor Steve Jones thinks that this is where evolution has actually speeded up and is really active. But he thinks it's speeding up towards a grand averaging out, where, over hundreds of generations of this great mixing, individuals will end up, genetically very fit, but as a species, very homogenous. And we won't know what the consequences of this might be.

Adam attempts to untangle another evolutionary pressure - that of sexual selection. Who we choose as a mate, also has an effect on our evolutionary trajectory. Kevin Laland from St Andrews University thinks that our cultural preferences can be stronger than genetic preferences, which means that sexual selection could become a more important driving force for human evolution in the future.

As to whether we're evolving greater intelligence? No chance says Steven Pinker!

Producer: Fiona Roberts.

The effect of globalisation and a greater choice of partners on human genetic evolution.

Adam Rutherford asks how talking, travelling and technology affect human genetic evolution