25 June 2012
ByAppeared in BioNews 662
Marcus Brigstocke Invites Mark Thomas
Pillar Room, Imperial Square, Cheltenham, Gloucestershire GL50 1QA, UK
Sunday 17 June 2012
How are we different from animals? Comedian Marcus Brigstocke met evolutionary geneticist Professor Mark Thomas at the Cheltenham Science Festival, and asked him about what makes humans so human. Their marvellously informative discussion of human achievement covered art, religion, Adam and Eve, and how they all tie into our genes.
Evolutionary genetics is a field of research that stems from Darwin's theories of evolution. Scientists working in this area study evolution by looking at the genes and genotype frequencies in today's population.
Professor Thomas explained that the way people evolve is particularly interesting, because we accumulate our culture and customs from one generation to the next. The technologies and artwork we create are a result of countless earlier generations. What scientists don't know is whether we are so good at accumulating expertise because we are genetically more advanced than most animals, or whether our culture has worked itself into our genes, and made us evolve at a faster pace. Evolutionary genetics poses these types of questions.
Professor Thomas pointed out that Brigstocke and he were both sitting on a stage in Cheltenham, being really quite nice to each other (and they were) even though they are not related. Most species, including chimps, are altruistic only to their relatives, because their main concern is for their own genes to survive in the future. Humans, on the other hand, make friends. One theory to explain this is that our species realised that actually, acting as a group gives us more of an advantage over other groups, than if we were alone.
But surely, Brigstocke pointed out, promoting the idea that everyone clusters into groups is an ideal excuse for conflicts and racism. Professor Thomas explained that this wasn't the case. If anything, genetics directly challenges racism. Genetic variation doesn't group people into discrete blocks. It is continuous, and the idea of race is a type of pattern that people have imposed themselves. The only barriers to the spreading of genes are physical obstacles such as the Sahara desert, or the Pacific Ocean, which make it difficult for people on opposite sides to reproduce.
It is difficult to ignore the skill with which humans use complicated language. Brigstocke pointed out that his career is built from telling stories. He asked how it was that language came about. Professor Thomas suggested that the type of language we use to tell stories most likely began in hunter-gatherer tribes. When people go out to hunt, their day is filled with a lot of waiting, and work only comes in bursts. This leaves a lot of time to fill.
The desire to create art is another very human trait, Brigstocke suggested. Professor Thomas thinks that are probably came about when tribes met other tribes, and wanted to share their culture. However, it has also been suggested that the very first examples of human drawings were done by a group of teenage boys trying to show off to their girlfriends.
The idea of evolution is not easily compatible with many religious beliefs. Brigstocke wondered whether Professor Thomas had ever had much active opposition from religious groups. 'Not really', he answered. In fact, some recent genetic research has received strong support from a Jewish caste called the Kohanim. Tradition dictates that the Kohanim are all men, descended from a single ancestor, the brother of Moses.
Because the Y chromosome is inherited only from the father, males of the same lineage will share common snippets of DNA sequence, called haplotypes. Genetic testing suggests that almost half of Jews with a family tradition of being Kohanim have very similar DNA sequences on the Y-chromosome, implying that they could well share a common ancestor. Only 5-8 percent of Jews without the tradition have similar sequences. Moreover, the amount of time for this common DNA to have evolved to its present appearance is not far from 3,100 years ago. This more or less fits with when Moses is thought to have lived.
Professor Thomas described another encounter with a strongly religious group. When archaeological researchers began to dig for human remains, several people objected to this apparently inhumane treatment. With carbon dating, the archaeologists were able to demonstrate that the remains were more than eight thousand years old, before humans should have been created by God. There were then no further objections.
'Who were Adam and Eve?’, asked Brigstocke. 'They came right after the people being dug up', quipped Professor Thomas. 'But seriously', Brigstocke countered, 'can we trace back the genetic lines of men and women?'. Professor Thomas explained that we can estimate how closely men are related through their Y-chromosomes, as with Kohanim Jews. It is possible to deduce that the first man should have lived in Africa, around 130 thousand years ago. We can do a similar trace in women, by looking at mitochondria, which are inherited only from one's mother. The first female should have lived 180-200 thousand years ago. This poses a very pertinent question: did Adam and Eve ever meet and if they didn't, how do we exist?
For me, this talk highlighted evolutionary genetics as a subject full of starkly fascinating questions. Often, however, it seemed to be richer in hypotheses than data. Even so, this talk left me wanting to ask and know a lot more.