PRIMATES &
HUMAN EVOLUTION
When the first primates, about 65 million years ago, developed flat nails, this evolution was surely caused by the behavior of their own ancestors.
If you lose your claws, it's probably because you aren't using them that much and that a new activity is creating the need to improve this tool.
The sharpness of the claws was removed so they could touch and manipulate their own skin without hurting themselves, partly to help them do a better cleaning job.
So our ancestors, at least those early ones, were possibly peace-loving and non-aggressive, but also clean individuals.
Flat nails represent only part of the physical changes needed to make grooming possible.
The whole fingertip became a probe with;
•The development of an ultra-sensitive pad beneath,
•The creation of a «nail bed» below the nail plate. Packed with nerve endings, it amplifies the sensations coming from the nail.
Grooming also needs specific nervous processes to be in place.
Most grooming is induced by itches and pains generated by the skin of the locations that need it.
You respond to signals.
Also, while grooming, your actions are guided by specialized sensations coming from the skin itself.
Some think that the first primates, along with their ancestors, were nocturnal animals.
I agree with this hypothesis because grooming is entirely based on the sense of touch.
It is the sense of touch repairing itself, so the individuals doing it must concentrate on this sense above all others.
The sensations that one experiences are personal and cannot be felt by someone else, so I think grooming has developed as a solitary activity.
Taken from the Nails page on this site
Just like hooves, fingernails have evolved from the claws of reptiles.
About sixty-five million years ago, a reduction in the thickness of the deep layer of the claw led to the advent of nails in the first primates.
Primates aren't the only ones to have flat nails, some marsupials also have them.
This is a good example of parallel evolution; which is the development of similarities in separate lineages.
It shows that flat nails are an important goal for evolution.
There is an intermediate evolutionary step between claws and nails; it is called the toilet-claw.
The first primates had them on the second digit of their hands and feet.
Just like nails, toilet claws are made of keratin.
Their shape is similar to claws, but their tip isn't as pointed.
Prosimian primates still have toilet-claws nowadays, while the nails of a few South American monkey species have reversed back to claws.
We've all observed dogs scratching.
Some animals will rub their hide against a rock or a tree, while others will roll over on their back and grind their skin onto the ground.
Of course, parasites could be causing their discomfort, but my observations tell me that these animals feel the same unpleasing itches and pains that we do.
Animals with hooves are very ill equipped, while those with claws can't apply any pressure on their skin without piercing it.
Yet, the healing effect of grooming is based on putting pressure on the skin.
The flattening of the claws had to evolve from a continuous will to act, to work on the source of the nagging sensations.
I don't believe that the grooming activities pictured at the top of this page are those that led the first primates to evolve flat nails, nor that they would be sufficient to provoke such a change.
© Paul Williams
© David Dennis Photos
© .robbie
© thsutton
We've all seen pictures and films of primates grooming one another.
One individual is doing the grooming work (the groomer), while the other (the groomee) takes a stiff pose.
In almost all cases, the groomers are using their sense of sight to guide their actions.
Grooming is the process of unfolding the skin and cannot be confused with pest and debris removal.
It is sad for me to say that none of the primates above are doing any grooming.
This affirmation is based on my own experience of grooming and of the movements it demands.
The two main problems are;
•Their use of sight,
•They aren't doing it individually.
This being said, some primates probably groom correctly, as explained below.
Several things are being done;
•Removing parasites, most are promptly eaten,
•Cleaning the fur,
•Scraping away skin imperfections,
•...
The groomer will pick off anything abnormal from the fur of the groomee; lice, ticks, fleas, insects, bits of wood or grass, ...
If something strange is spotted on the skin itself though, it will be investigated with the nail; so scabs, pimples, spots, ... will all be scrubbed off.
This last point is important, because while they work on the skin itself, a bit of real grooming is performed.
After the first primates developed grooming, we've seen how our ancestors began using vision rather than their other senses.
This has resulted in an over-reliance on that sense.
This tendency had adverse effects on their grooming technique because, as explained in the mirror usage section;
•Folds can hardly be seen,
•If you use your sense of sight, it overwhelms your weak sense of touch.
All the grooming procedures can be performed at night, with your eyes closed or looking elsewhere.
You can feel the folds with your nails, but you can't see them.
Grooming depends on sensations coming from the skin to direct and steer your actions.
If you use sight, it is so powerful that you rely on it immediately and all your technique changes.
The situation is further complicated, for all the other primates, by their thick coat of fur.
Grooming lets you use your nails and fingertips to remove dead cells and unfold the skin of your body and face.
The following video will get you started:
You can often see for yourself if a primate is well or badly groomed.
You just have to look at their skin.
In most cases, primates have visible folds that they would not have if they had, even lightly, groomed the area.
© Picture Taker 2
© Picture Taker 2
As you can see, you are already an expert on folds because you observe them on humans.
However, the folds often aren't visible; they appear as ugliness for years before you can spot them.
Great apes are among the most badly folded of all primates.
Their nose becomes flattened to the point where their breathing is surely inhibited.
Researchers who closely monitor their activities tell us that they spend, on average, between one and two hours a day grooming.
All species, sub-species and even some communities have their own habits and refinements.
We can distinguish three different usages;
•Motherly grooming,
•Social grooming,
•Self-grooming.
The social aspect leads primates away from grooming properly.
Self-grooming is done by one individual in solo.
It is of greater interest to us because it often represents real grooming, the kind that unfolds the skin.
The problem is that self-grooming is very intimate and mostly performed when one is alone.
Because of this, we don't really know how much self-grooming is done.
As soon as the baby is born, it is greeted into this world by the warm tongue of the mother, licking its face.
She will remove what remains of the birth membranes and lick the newborn clean.
A few minutes later, she will start grooming the baby, while inspecting it.
Several of these grooming sessions will take place daily and this care is extended throughout childhood, sometimes into adulthood.
Unfortunately, the mother's grooming technique is biased since she uses her eyesight and this prevents her from doing an acceptable job at unfolding the skin.
© fortes
She may, on the other hand, be doing excellent work at removing pests and keeping the fur clean.
Grooming abilities acquired by the children should transform into self-grooming habits at adulthood.
But they don't.
Instead, the individuals try to replace their mother's grooming with someone else and this becomes social grooming.
Grooming is the most important social activity for almost all species and it plays a major role in diffusing tensions among groups.
The emergence of the social aspect of grooming is very similar to what the bonobos have done with sex.
In bonobo groups, sex has been diverted from its reproductive role, then subjected to social customs.
In a similar manner, the procedures and rules implemented in social grooming steer it away from its skin unfolding function.
Social grooming wouldn't be bad if it was performed equally by everyone on anyone, but it is often based on the rank of the participants.
© kibuyu
Nevertheless, social grooming promotes closeness and «taking care of others» attitudes that certainly have several advantages.
It serves as a cement for their communities.
Regrettably, their use of sight totally overpowers the sense of touch that they should be concentrating on.
As a result, very little real grooming is performed and their skin remains folded.
Grooming became an instinctive behavior in primates at least 65 million years ago.
What has happened of it?
How has it evolved in humans?
The answer is simple; you feel this instinct to groom several times a day, you call it itching or pain.
So you react totally incorrectly; by scratching or ignoring it.
This attitude stems from an over-reliance on sight.
Instead, you should be exploring your skin with your sense of touch.
SKIN CARE
BEAUTY
HUMAN EVOLUTION
PRIMATES