Tiny mutation may have shaped modern humans, scientists say

Description: Scientists discover that about 30,000 years ago, a tiny genetic mutation known as EDAR arose in the human genome. Scientists are able to observing how EDAR affects mice. This small genetic change is one substituting chemical letter of DNA for another. This may have helped the people in Asia adapt to their environment by giving them extra sweat glands and to grow thicker hair or fuller breasts. The path to find this mutation was hard because the beneficial mutations to track are usually passed down with thousands of variants that happen to live in the chromosomal neighborhood. The researches used powerful computers to sort through the human genome to identify genetic changes that can be linked to our evolution. To understand how these mutations affected humans, the researches tested it first on mice. The EDAR gene was able to thicken the hair of the mice and changes in sweat glands and mammary glands. The change in sweat glands surprised the researches since they expected larger teeth, which didn't show up, and thicker hair. Since they didn't expect a change in the sweat and mammary glands, they were surprised to find out that this happened. To confirm that this also happened among the humans too, they examined the fingertips of 623 people with the EDAR gene from China. They found that humans too had this change in sweat glands and mammary glands. All of these results show how the EDAR mutation may have helped drive evolution. Scientists hypothesized that there were two ways of this mutation being passed on. One of them being since the humans had bigger sweat glands, they were able to survive in the environment and reproduce more because of this. Second, the thicker hair or bigger breasts might have been more appealing to a mate causing them to be chosen over other available options causing this mutation to be further passed on. This story was similar to the story of the TLR-5 gene, which is involved in protecting the body from certain bacteria. The research team's analysis suggested that many of these mutations weren't mutations in the gene themselves, but in parts of the chromosome.

Relevance: This story connects to our unit on evolution, heredity, and molecular genetics.  This articles relates to how a mutation helped a certain species survive. This is evolution itself as evolution is the development of species through different beneficial mutations. It shows how species gain a mutation that is beneficial to them and because of it they are able to survive and reproduce better. It also shows how in DNA sequencing, a genetic mutation like the changing of one nucleotide can change a lot. It also shows genetic mutations in the DNA sequencing or in the chromosome itself such as the substitution of one chemical letter of DNA. It also connects to our heredity unit due to the fact that his mutation was passed on through heredity.


Published: February 14, 2013
Link: http://articles.latimes.com/2013/feb/14/science/la-sci-human-evolution-genes-20130215