View Full Version : Evolutionary Origins of Red Hair

Fire Haired14
28-12-15, 02:18
About 20 years ago it was discovered that a handful of mutations in the MC1R can explain most Red hair. These mutations were called RHCs. However, no one discovered a single mutation which most Redheads share, if RHCs belong to haplotypes, and what the origins of those haplotypes are. This week I discovered a single mutation most Redheads share, discovered the primary RHCs belong to haplotypes, and the origin of those haplotypes.

Single Red Hair Mutation

Chromsome: 16
Gene: AFG3L1P
SNP: rs9939542
Position: 90053048
Alleles(Ancestral/Derived): C/A
Red hair Allele: C

The vast majority of Redheads have a C allele in this SNP and the majority have CC. Very very very few non-Red haired Europeans have CC. rs9939542 itself does not cause Red hair. The reason rs9939542 is linked with Red hair is because it is apart of a haplotype with Red hair variant(RHC) R151C(rs1805007 T) and Red hair variant(RHC) R160W(rs1805008 T). Many Non-Europeans have a C allele and many have CC. This is mostly because many belong to haplotypes related to the haplotypes R160W(rs1805008 T) and R151C(rs1805007 T) belong to. I explain this more in the next section.

Red Hair is the Result of the Combination of Many Haplotypes

By looking at SNPs in the 16 Chromsome which are near SNPs rs1805007 and rs1805008, I discovered R151C(rs1805007 T) and R160W(rs1805008 T) are apart of large haplotypes which include many SNPs. By looking at the calls non-Europeans get in those SNPs, I discovered that the haplotypes R151C(rs1805007 T) and R160W(rs1805008 T) belong to are a combination of haplotypes common all over the world. I call these haplotypes "Pre-Red hair Haplotypes"I illustrate it in this spreadsheet: Evolution of Red hair (https://docs.google.com/spreadsheets/d/1yFEFM10voF1NTIHfkcR4h_8lKp8LJCmcP8sQxc2T-SQ/edit#gid=2009213555).

I investigated the frequencies of pre-Red hair haplotypes in HGDP populations of R160W. Here's a brief description.

Africa: Essentially all Africans have H1 or H3. It is practically impossible to find one who has H2, H5, H6, or the Red hair version. I did find one African(Kenya) who had H5.
East Asia: Many have H1 and few have H3. It is practically impossible to find one who has H2, H5, H6, or the Red hair version. I did find one East Asian(China) who had H5.
South Asia: Many have H1 and H3. And unlike Africans and East Asians, a significant amount have H2. It is not rare for South Asians to have a combination of H1, H3, H2. The reason some have a combination of H1, H3, and H2 is probably because very close relatives of H5 and the Red hair version exist in South Asia. And also some but very few(~0.5-1%) have the Red hair version.
Europe: Many have H1, H3, H2, and the Red hair version. It is not uncommon for a combination of H1, H2, H3 to exist, but it is uncommon to find H5.

Outside of Europe the only place there's close relatives of the R160W haplotype and the actual R160W haplotype is in South Asia. I haven't investigated R151C haplotype frequencies, although outside of Europe the only place the R151C haplotype exists is South Asia. The pattern makes sense when you consider genetics. Essentially all of European's and East Asian's ancestors separated 45,000+ years ago, and for Africans even longer ago. On the other hand South Asians and Europeans have lots of common ancestry in the last 30,000 and even 15,000 years(CHG).

I haven't discovered the origins of Red hair but I've discovered how Red hair(or at least the two many variants) came about. It's a combination of multiple haplotypes in Chromsome 16. Mutations pilled up and as the number of mutations became bigger and bigger, the end result was Red hair.

Fire Haired14
28-12-15, 17:20
Something interesting I learned:

There's a Redhead from Afghanistan who tested at 23andme. She belongs to a haplotype very closely related to the haplotype Red hair variant R151C is in. Less than 1% of South Asians belong to a haplotype this related, it isn't a coincidence. Note: That East Asia and Africa lack haplotypes closely related to the haplotype Red hair variant R160W is in, while many South Asians belong to closely related haplotypes. So, for the evolution of Red hair, it looks like it happened specifically in the Western half of the world after the Out-of Africa event.