In us, there are three types of lice, namely: head lice, body lice and pubic lice. Although they are all lice, they are very different. Head lice can only live on the scalp, body lice can only appear on clothing, and pubic lice can only live on the genitals.
So what's going on here?
<h1 class="pgc-h-arrow-right" data-track="3" > lice</h1>
In our eyes, head lice, body lice and pubic lice seem to be the same organism, but in fact, there is already reproductive isolation between them, unable to reproduce the ability to reproduce offspring, and different varieties have been formed.
Among them, head lice evolved, in order to better grasp human hair, evolved unique claws, claws with toe bone claws, as well as thorn hairs.
When these two parts work together, they allow lice to better grasp the human hair.
Even if we shake our hair every day, they will not let go and fall off, and can only be cleaned up with special tools.
Compared to pubic lice, head lice are larger, but the body is more slender, because our hair is relatively dense, and head lice do not require a large body spacing and can also grasp the hair very well.
Pubic lice are different, compared to head lice, the pubic lice are smaller, and its body width is almost the same as its length, sometimes wider. This is because pubic hair is thinner and spaced farther apart than hair, and pubic lice have evolved to adapt to this environment.
Like head lice, the claws of pubic lice are able to hold the hair tightly and move freely in the hair, but unlike the head lice, the second and third legs of the pubic lice are much thicker because the hairs on the pubic area are thicker than the hair, so their claws can hold thicker hairs, but they cannot hold the finer hairs.
The human body also has a third type of lice: body lice, which are the largest. It is worth noting that the body lice is not to grasp the sweat of the human body, but to grasp the fibers of the clothes, Zhang Ailing once said: Life is a gorgeous robe, which is full of lice, this lice is "body lice".
Neither head lice, body lice, or pubic lice can leave their active areas or they will die quickly, for example, after the head lice leave the warm, wet scalp, they will die of hunger and cold in just a few hours.
In addition, if the pubic lice are placed on the hair and the head lice are placed in the pubic position, they are also difficult to survive, because their body structure is difficult to adapt to each other's environment.
Head lice have difficulty grasping thicker hairs, while pubic lice cannot grip thinner hair, so neither of them can survive long in each other's environment.
It is worth noting that lice are actually infectious diseases, head lice can be transmitted through the contact of two people's hair, while pubic lice are mainly transmitted through sex; body lice will be transmitted through clothes and bedding.
<h1 class="pgc-h-arrow-right" data-track="16" > humans to shed body hair and put on clothes</h1>
In fact, the little lice also hide information about human evolution.
Humans are also known as "naked apes", but the question of when humans shed their body hair and when to put on their clothes needs to be answered from lice.
In 1999, scientist Mark M. Stogin received a message from his son that two students at the school had head lice in their hair and wanted parents to pay attention to their children's hygiene and safety.
mark. Stogin keenly felt that lice might help to unravel when humans shed their hair, because whether they were body lice, head lice or pubic lice, in the past they all had the same ancestor, but gradually separated in the process of later evolution, in which the key factor in the separation of head lice and pubic lice was the loss of body hair in humans, and the body lice evolved from head lice, and the key factor in their separation was that humans put on clothes.
mark. Stogin, a molecular scientist who used this key information to use modern molecular science to derive the separation of head lice and pubic lice, dating back as far as 1.14 million years ago. Scientists have found that the temperature in Africa during this period is very high, and it is likely that humans have shed all their body hair in order to better dissipate heat, leaving only part of the hair.
About 170,000 years ago, head lice and body lice diverged, which also indicates that humans at this time have put on clothes. The study found that during this period, due to the influence of the Quaternary Ice Age, the temperature dropped in many parts of the world, and it was very reasonable for humans to wear clothes at this time.
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In addition to humans, many animals also have lice, such as gorillas, and one of the ways they enhance their feelings is to comb each other's hair and catch lice.
The lice species in each animal are different, for example, lice that live on birds cannot live in gorillas; and vice versa.
Compared with humans, these animals have only one kind of lice, the main reason is that they do not shed hair, but retain the hair of the whole body, lice can move from one place to another unimpeded, so there is no reproductive isolation.