The mutation on 17p has been identified by a Turkish/German team in Berlin headed by Professor Stefan Mundlos. They suggest, some would say controversially, that this mutation could have knocked out a gene that plays a role in bipedal walking, atavastically exposing an earlier form of walking.
Professor Humphrey believes, however, that this mutation has merely caused the cerebellar hypoplasia confirmed by MRI scans, and which makes it so difficult for them to balance upright. He argues that it’s likely to be a conjunction of other factors that has kept the siblings on all fours. These include what seems to be a familial predisposition to bear-crawling as children (all 19 children, including all the healthy ones, did it), and a mix of other cultural influences such as lack of a pro-active health service.
But whatever the mix of nature and nurture, the family still raises some interesting evolutionary questions. They mostly use a diagonal gait better suited to branch-walking than terrestial walking (suggesting it could still be hard-wired in us). They are also palmigrade rather than knuckle-walkers, and the paleoanthropologists have expressed interest in seeing what impact walking this way has had on their skeletons. It could help them tease out what anatomical features are and are not important in the fossil record.
It is also interesting that they balance extremely well on four, showing none of the ataxia they display on two. This has led another researcher, Dr John Skoyles (LSE), to suggest that the gene that has been knocked out might be one which has a role in humans’ “superbalance” ability.
As you might imagine, we have been dismayed by some of the newspaper reporting. Not one major newspaper has reported the science accurately – a result, of course, of a widespread lack of understanding of even basic scientific principles. There has also been considerably confusion over which scientist is saying what (is is only, for instance, the Turkish scientist, Professor Uner Tan, who suggests they are a wholesale genetic throwback).
Our film will, I hope, redress the balance and be seen as a sensitive, thorough and thought-provoking record of the family/phenomenon. We made it not for voyeuristic reasons (although of course the quadrupedal siblings are visually arresting) but because we thought it raised all kinds of fascinating scientific, and many other, questions. I think the reason it’s created such a fuss because bipedality is something that defines us as human beings – separate and distinct from beasts – and their existence is challenging philosophically. You only have to look at the Bible, for instance, to see how the word “upright” is loaded with meaning about purity, morality etc. That’s ingrained very deeply in us.