It's long been presumed the unusually fair-haired Melanesians were a result of long-ago liaisons with European traders, while locals often attributed their golden locks to a diet rich in fish or the constant exposure to the Sun.
But a study just published in the authorative journal, Science says the reason why five to 10 per cent of Solomon Islanders are blond is due to simple genetics - a gene called TYRP1 that is unique to the Solomons.
Speaker:Dr Eimear Kenny, Stamford University
KENNY: We think it's actually in about 25 per cent of people from Melanesia. We've studied people from Solomon Islands, but we also think that it's the underlying cause of blonde hair generally in Melanesia. And we think about 25 per cent of people are carriers. It is of course a recessive gene, which means that both the mother and the father need to pass a copy on to the child for the child to have blonde hair, and that's why we see about five, ten per cent blonde haired people in Melanesia.
COUTTS: So does it miss generations or is it simply due to both parents having the gene?
KENNY: It doesn't miss generations, it's simply due to both parents having the gene, yeah.
COUTTS: And when did you discover it, how did you discover the gene?
KENNY: Well this was really sort of a very collaborative project with my collaborators in Max Planck Institute in Liepzig, who have been studying populations in Melanesia for quite some time now, who while out there had noticed this really striking, what we call a 'sena' type, and really just had a very simple genetic hypothesis; was this something that was genetic or was this something that was caused by exposure to sun and diet etc. So a couple of a years ago my colleagues, Sean Myles and Nic Timson while out in Solomon Islands collected the data by asking people to participate and explain the study, people volunteered and participated and gave some saliva samples and allowed us to measure their hair. And then later we took that data back to Stanford University where I worked, and we geno-typed individuals, that is to say that we measured some of the variability of the genomes of some of the people who volunteered for the study, and then we just looked at differences between people who have very blonde hair and very dark hair. And straightaway we found a single signal that was underlying this sena-type and active gene called TYRP1.
COUTTS: As I mentioned in the introduction, it was presumed that the unusually fair-haired Melanesians were a result of long-ago liaisons with European traders, maybe from Scandinavia. Is this the case, could that gene have been introduced that way?
KENNY: No in fact we found no evidence of what we would call gene flow or genes being brought to Melanesia by early European traders or explorers, which was sort of one of our hypotheses, because of course one other place in the world that you see blonde hair in high prevalence is Europe, but that's all the way over the other side of the globe. What we found instead was that the single variance that causes blonde hair in Melanesia is absent outside of Melanesia. So that our conclusion is that blonde hair is arisen at least twice in human history that we know of.
COUTTS: What else do you know from this gene? What else does it do apart from introducing blonde hair? I mean is there a blue eye or what else does it do?
KENNY: That's very interesting, so it is part of what we call a u-melanin pathway, so melanin is what gives hair and skin and eyes their colour, but there are different pathways for eye colour and skin and hair colour. So this particular gene in Solomon Islanders certainly has a very strong effect on hair colour. We did notice that it had quite a milder effect also in skin colour, and we're following that up with further study.
COUTTS: Ok and is that why it's specific to certain areas as well within Solomon Islands for instance?
KENNY: Well now there's many sort of periods and there is a sort of realm of speculation how in these variances arose in the Solomon Islands. Some people might say that this it's a very old and it might have arisen when small numbers of people pre-omlithickly(?) came to Solomon Islands and just by chance this particular ?? kind of arose to high frequency and this impact on hair colour in the area.
COUTTS: It's got nothing to do with albinism?
KENNY: This particular mutation that we found does not give an albinism sena-type. However this same gene, the TYRP1 with different mutations in the gene can, and in fact there's no cases in particular of individuals of African descent that have different mutations in this same gene that have albinism.
COUTTS: And so does it have the same effect, are they light sensitive, does their skin burn more easily like albinos do?
KENNY: These are very interesting questions that we're planning to follow up. We haven't found any reports yet of people complaining about this, these are definitely interesting questions that we want to follow up.
COUTTS: And do they stay blonde right through their lives?
KENNY: We find actually that where you see this blonde hair most strikingly really is in children, and as people grow older their hair gets darker. It's the same actually in European blonde hair, people go older, a lot of European who are blonde in childhood actually become quite dark haired in adulthood. So you can definitely see that the blonde hair does darken as people grow older in the Solomon Islands also.