How domesticating species changed humanity
On Wednesday 18 April, Professor Alice Roberts came to The Perse to deliver the Summer 2018 Community Lecture, in partnership with The Cambridge Building Society.
Alice Roberts is a familiar face from our television screens, and we were delighted to welcome her to The Perse for our first community lecture in the Peter Hall Performing Arts Centre, in partnership with The Cambridge Building Society. She even began her lecture by revealing a Perse connection, as OP Micky Lachmann (1989) has produced a number of her programmes.
Alice started her career as a medical doctor, and her work has mostly looked at the history of humans, bringing together evidence and expertise from archaeology, palaeontology and genetics. Due to our growing knowledge of genetics and increased ability to process large amounts of genetic data, this is a field that has burgeoned in the last five to ten years. During this time, Alice became interested in the species that have teamed up with humans to help us become who we are today, a process which also shows how fast evolution can work. The result is her latest book, Tamed: Ten Species that Changed our World, three of which featured in her lecture.
Most domesticated animals and plants arrived at the beginning of the Neolithic period when people began to farm, but one species was domesticated earlier – wolves. Alice spoke at length about how dogs have been man’s best friend for a very long time, although exactly how long has recently been a subject of heated debate. Archaeological evidence had put the date at which domesticated dogs diverged from wolves at around 14,000 years ago, before farming began around 10,000 to 11,000 years ago. The first information from genetics in 2002, looking at mitochondrial DNA, seemed to confirm this with a date of 15,000 years ago, but tantalisingly gave a possible much earlier date of 30,000 to 40,000 years ago if the data was viewed differently. A subsequent study took the date forward to 15,000 years ago, until genetic analysis of a 34,900 year old wolf bone confirmed the rate of mutation in wolf DNA, which is used to determine how long ago species separated. It turns out this was 60% slower than was thought, putting the date at which dogs and wolves separated back to around 30,000 to 40,000 years ago. This detailed insight into the scientific research process revealed the frustration and excitement of working in a cutting-edge field where new evidence constantly challenges our assumptions and beliefs. There are still mysteries to be solved; for instance, we don’t know exactly where the first dogs came from. The first specimen we think is a dog – its mitochondrial DNA is found in dogs today, but we can’t be totally sure – was found in Razboinichya Cave in Russia, so it is affectionately known as ‘Razbo’. Alice is on a mission to get as many people as possible to name their dog Razbo in its honour.
The warming climate after the last ice age opened the door for farming, as rising carbon dioxide levels created an ideal environment for wild cereals. These began to be cultivated in various sites, notably in the Fertile Crescent and Far East, probably after wheat started planting itself when grains were dropped around settlements and innovative humans saw the potential to plant it deliberately. Around this time we also domesticated cattle, sheep and pigs, to the extent that there are no longer any wild cattle – all those we think of as ‘wild’ are actually domesticated cattle that have gone feral. We also started to evolve ourselves as a result of keeping livestock. Alice asked us to put up our hand if we could drink a glass of fresh milk without any serious digestive consequences. Most of the room raised their hand. This is because most European people are ‘mutants’ and have inherited a mutated gene that allows us to digest lactose beyond infanthood. For our ancestors, being able to access the nutrients in milk would have helped them to survive and pass on their genes.
At this point, Alice debunked a few diet myths. If you are able to digest it, milk is a highly nutritious foodstuff, as it contains everything a baby animal needs, while the trendy ‘Paleo’ diet assumes we haven’t evolved since the Palaeolithic. However, we shouldn’t hold our breath for an Alice Roberts diet book. As a former doctor, her common sense advice of ‘eat lots of fruit and vegetables and some oily fish, but not too much red meat, salt or sugar, although there’s no need to cut them out entirely, and don’t drink too much’ would barely fill a page.
The third species in the lecture, horses, were domesticated fairly late, around 5,500 years ago. Experienced horse hunters on the Eurasian Steppe may have tamed them to assist with their hunts. There are fascinating links between the spread of Indo-European languages and the migration from the Steppe of people who had domesticated horses, which is also reflected in the genetic evidence. Horses profoundly changed human society, allowing us to cover large distances quickly, as well as transforming warfare, in which they played a significant role up until the twentieth century.
Working in such a fast-paced field means that Alice is keen to revise some of her earlier work, such as the series The Incredible Human Journey. When it was made a decade ago there was no genome-wide data, while we thought there had been no interbreeding between Neanderthals and humans. After the Neanderthal genome was mapped in 2010 we know that there was. In fact, we carry within our genes the ghosts of other species we haven’t found any fossil evidence for yet.
Alice’s work may look into the distant past, but it also raises profound questions about our future. The population boom that started in the Neolithic is only just levelling off now, and we farm 40% of the Earth’s surface. How can we sustain ourselves while protecting other species and natural environments? Genetics has taught us that the species barrier is more permeable than we previously thought, so should we utilise the technology that already exists to edit our genes? Alice believes that the big challenge for this century is how humans stop fighting against the wildness on our planet but learn to thrive within it.
The Perse holds termly Community Lectures, open to all in the community, whether or not they have a link to the School. Information about upcoming lectures can be found here.