One of the reasons that I have become increasingly interested in archaeology is the amount of information it can provide to us about clothing during time periods where other information is virtually non-existent. However, other disciplines can also assist the clothing historian when even archaeology fails.
Such as genetics.
I learned from David Beard's Archaeology in Europe blog that biologists have recently established that humans started to wear clothes on a regular basis about 170,000 years ago. They did so with the help of lice. How's that?
Beard's blog pointed to this article from Medical News Today, which described a University of Florida study of lice DNA. It appears that human body lice are extremely well-adapted, not just to living on humans, but to living on humans who are wearing clothing. By tracing when the DNA of body lice began to diverge from the DNA of head lice, researchers could tell when clothing had become well enough established that a different variety of lice had evolved to live in the conditions it created. Apparently clothing started to be worn on a regular basis when humans moved out of Africa and started crafting and wearing garments to survive in colder climates.
I really liked this article because it confirms what I have come to believe over the past 20 years, namely, that we will only be able to piece together a complete history of costume by using information gleaned from multiple disciplines. Archaeology is important, but the lice study shows that the sciences can provide necessary information too.