The longer answer goes back over 800,000 years. Scientists believe head lice began to evolve on a different path than body lice about the time humans started to wear more clothing. Body lice evolved to attach to clothing fibers which are typically thicker and stronger than a human hair.
Researchers are unsure where lice originated, but they know that lice have affected primates for at least 25 million years, eventually spreading to humans. Head lice only affect humans, and they will not jump onto pets or other animals. Lice can also travel on objects that have touched the head.
One is universal and evolved on modern human heads. The other, found only in the Americas, they think probably evolved on an earlier and now extinct human species, and jumped onto Homo sapiens during an encounter in Asia 25,000 to 30,000 years ago, perhaps during fights, sex, the sharing of clothes or even cannibalism.
Recent studies have shown the benefits of having lice. While it may sound ridiculous and unbelievable, there's scientific evidence that a certain kind of louse can be beneficial in reducing the chances of developing immune deficiencies.
The first humans emerged in Africa around two million years ago, long before the modern humans known as Homo sapiens appeared on the same continent. There's a lot anthropologists still don't know about how different groups of humans interacted and mated with each other over this long stretch of prehistory.
Kill head lice by washing infested articles in hot water (at least 140°F) and drying in a hot dryer. Items that cannot be laundered such as headgear, earphones, and bike helmets, can be placed in a plastic bag and put in a freezer. If the freezer is 5°F or lower, all lice and eggs should be dead within 10 hours.
Head lice are annoying, but they're not dangerous and they don't spread disease. They're not a sign of poor hygiene — head lice need blood and they don't care whether it's from someone who's clean or dirty. It's best to treat head lice right away to prevent them from spreading.
Some stories suggest that simple-minded folk believed if they wore fur coats and clothes that the lice would make their way down onto the warm fur. It may not have been a realistic cure for lice, but at least they would've been warm through the winter weather.
“We've discovered the 'smoking louse' that reveals direct contact between two early species of humans,” probably in Asia about 25,000 to 30,000 years ago, says study leader Dale Clayton, a professor of biology at the University of Utah. “Kids today have head lice that evolved on two species of cavemen.
Genetic studies suggest that lice developed about 1.68 million years before homo sapiens emerged, and that they started their relationships with humans about the same time human evolution separated from chimpanzee evolution.
Ten infected lice are sufficient for plague transmission (4), and our observation that one third of infected lice remained alive 3 days after infection indicates that an index plague patient carrying as few as 30 body lice could be a source for plague up to 3 days after dying.
Adult lice can live up to 30 days on a person's head. To live, adult lice need to feed on blood several times daily. Without blood meals, the louse will die within 1 to 2 days off the host. Life cycle image and information courtesy of DPDx.
Left untreated, head lice can lead to secondary infections, which can be serious. Bacterial infections, such as impetigo, can occur when scratched bites become infected; this can have serious consequences if not treated properly.
Permethrin lotion 1% is approved by the FDA for the treatment of head lice. Permethrin is safe and effective when used as directed. Permethrin kills live lice but not unhatched eggs.
Coconut, tea tree oil, lavender, eucalyptus, rosemary, lemon grass, and peppermint are scents popularly believed to repel lice. Using any coconut scented shampoo and conditioner is an easy way to increase your defense. At 1% concentration, tea tree oil killed 100% of head lice after 30 minutes.
Lice don't care if hair has been colored. As long as a louse can grab on to a hair strand, it can make its way to the head where its food supply (blood) is. Myth #6: Lice like dirty hair.
Lice and nits can't survive the high heat. It's true that lice and nits can't survive temperatures above 113°F (45°C). This makes them susceptible to any heat source, such as a hairdryer or the plates of a hair straightener.
Heat Method:
There are recent studies that show that treatment of lice with heat can be quite effective in killing head lice. Products such as Lousebuster are very effective but even a home hairdryer can successfully treat lice.
You Have to Treat Them
Head lice will not go away on their own. If you think your child has an infestation, there are several steps you should take right away. Call your doctor to confirm the diagnosis. Notify your child's day care or school so other students can be checked.
Since Earth is about 4.6 billion years old, these finds suggest that the origin of life must have occurred within a few hundred million years of that time.
Broadly speaking, evolution simply means the gradual change in the genetics of a population over time. From that standpoint, human beings are constantly evolving and will continue to do so long as we continue to successfully reproduce.
“It means modern humans probably started wearing clothes on a regular basis to keep warm when they were first exposed to Ice Age conditions.”