It does not prove a cause and effect relationship between chemical straighteners and longterm hair losses, but it does create a level of uncertainty, said Dr. John Caruso, the cochief of an oncology program at St. Louis University School of Medicine.

Treatment for long-term effects The new study is a proof of concept, the researchers said. It does not prove a cause and effect relationship between chemical straighteners and long-term hair losses, but it does create a level of uncertainty, said Dr. John Caruso, the co-chief of an oncology program at St. Louis University School of Medicine. “I’m a little bit surprised that I’m excited about this,” Caruso said. “I think it’s premature.” One reason for the research is that hairs in many cultures have been dyed by heat, or without natural heat at all. Some cultures, specifically those found in Africa, where many of the world’s cultures arose, have been dyed by steam. “It’s a common phenomenon in cultures of the world who have been in contact with other cultures who also use heat.” Caruso said the new study gives no convincing evidence that heat alone is the cause of hair loss, but some genetic and environmental factors contribute to the hair loss, he said. Caruso was not involved with the new study. The new study is the first to look at chemical straighteners and hair loss in more than 150,000 women, about half of whom are black and who had a history of hormone therapy. Of those, 13,280 were postmenopausal, making them at high risk of cancer. About 14 percent of women who had long hair, and about 17 percent of women who had short hair, were women at high risk of hair loss. About 6 percent of women who used permanent hair dyes had cancer. People don’t normally have a high risk of balding, but that’s not true of chemical straighteners. “We were looking at this as a possibility,” Caruso said. “We were looking at it for some of our patients because they have long hair, and that didn’t translate to short hair.” One of the other possible reasons for the study’s findings is that chemical straighteners actually increase hair growth, he said. “We didn’t have a clear answer on that (probability of hair loss with chemicals).” For more information about the research, visit www.ncbi.nlm.nih.gov/pubmed/23162322.

The research can be found at: http://www.sciencedirect.com/science/article/pii/S0944007015001542.

The book takes you through all the major lines of evidence supporting human evolution out of Africa, the Middle East, and the rest of the globe. So let's go through the basics of drawing people and give you a few tips if you want to follow along with the process from start to finish.
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