Here's a short story:

Physically, clothing serves many purposes: it can serve as protection from the elements, and can enhance safety during hazardous activities such as hiking and cooking. It protects the wearer from rough surfaces, rash-causing plants, insect bites, splinters, thorns and prickles by providing a barrier between the skin and the environment. Clothes can insulate against cold or hot conditions. Further, they can provide a hygienic barrier, keeping infectious and toxic materials away from the body. Clothing also provides protection from harmful UV radiation. 

There is no easy way to determine when clothing was first developed, but some information has been inferred by studying lice. The body louse specifically lives in clothing, and diverge from head lice about 107,000 years ago, suggesting that clothing existed at that time. Another theory is that modern humans are the only survivors of several species of primates who may have worn clothes and that clothing may have been used as long ago as 650 thousand years ago. Other louse-based estimates put the introduction of clothing at around 42,000–72,000 BP. (End of story)

Provide your best guess for the following question. Give ONLY the guess, no other words or explanation.

For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>

Here are a few examples of questions and answers:

Question: what does clothing do?
Guess: serve many purposes

Question: from what?
Guess: it can serve as protection and enhance safety

Question: what does it protect from?
Guess: the elements

Question: what else?
Guess: rough surfaces, rash-causing plants, insect bites, splinters, thorns and prickles by \\

Question: how does it protect from those things?
Guess: by providing a barrier between the skin and the environment

Question: do other mammals today wear them?
Guess: no

Question: how long have people had clothes?
Guess: as long ago as 650 thousand years ago

Now answer the following question in the same format.

Question: how do we know that?

unknown